X300 Air Conditioning Self Test and Diagnostics

A VIDEO OF USING TEST MODE

To check for error codes in the Climate Control System with the internal diagnostics via the ‘Panel

Codes’

1. Ignition off - hold down AUTO and RECIRCULATION buttons and

switch on the ignition

2. press AUTO button - if ZERO shows, there's no stored

error codes

3. Press the RECIRCULATED AIR button to start diagnostic, sequence will start to test system.

4. press FACE button repeatedly to scroll through stored

fault codes

5. press FACE and HEATED REAR WINDOW buttons together to

clear a fault code.

6. repeat step 4 if there's more than one code

7. press FAN button to exit Interrogation Procedure

.

Control Panel Fault Code Listing

Reference fault code #23*: In ambient temperatures below 0°C, this code may be logged

because the low ambient causes a temporary low gas pressure. Where the ambient temperature

rises above 40°C, with the engine close to overheating, electrical feed to the compressor clutch

may be cut and code #23 registered.

0 Normal operation no fault codes present None Wait 30 seconds for system self-check.

11 Motorized in-car aspirator malfunction Harness / connector fault Sensor open / short circuit

Panel fault codes are not stored for motorized in-car aspirator motor failure.

12 Ambient temperature sensor malfunction Harness / connector fault Sensor open / short circuit

After rectification, disconnect the vehicle battery for 10 seconds to reset the system.

13 Evaporator temperature sensor malfunction Harness / connector fault Sensor open / short

circuit Refer to PDU

14 Water temperature input malfunction Instrument cluster output Refer to PDU

15 Heater matrix temperature sensor malfunction Harness / connector fault Sensor open / short

circuit Refer to PDU

21 Solar sensor Sensor open /short circuit Refer to PDU

22 Compressor lock signal fault Low refrigerant charge, low compressor oil level, loose drive belt

Harness / connector fault Adjust items as required

23 Refrigerant pressure switch malfunction Harness / connector fault Switch open / short circuit

Refer to PDU23 Refrigerant pressure low refrigerant charge *Leak from damaged pipe or joint

Rectify as required and recharge system

24 Face vent demand potentiometer fault Potentiometer open / short circuit Harness / connector

fault Refer to PDU

31 LH fresh / recirc. potentiometer fault Harness / connector fault In certain circumstances the

servo motor may over-travel and cause further logged faults. This may be cured, following fault

rectification, by cycling the ignition ON-OFF-ON 3 times Refer to PDU

32 RH fresh / recirc. potentiometer fault Harness / connector fault In certain circumstances the

servo motor may over-travel and cause further logged faults. This may be cured, following fault

rectification, by cycling the ignition ON-OFF-ON 3 times Refer to PDU

33 Cool air by-pass potentiometer fault Harness / connector fault In certain circumstances the

servo motor may over-travel and cause further logged faults. This may be cured, following fault

rectification, by cycling the ignition ON-OFF-ON 3 times Refer to PDU

34 Defrost vent potentiometer fault Harness / connector fault In certain circumstances the servo

motor may over-travel and cause further logged faults. This may be cured, following fault

rectification, by cycling the ignition ON-OFF-ON 3 times Refer to PDU

35 Centre vent potentiometer fault Harness / connector fault In certain circumstances the servo

motor may over-travel and cause further logged faults. This may be cured, following fault

rectification, by cycling the ignition ON-OFF-ON 3 times Refer to PDU

36 Foot vent potentiometer fault Harness / connector fault In certain circumstances the servo

motor may over-travel and cause further logged faults. This may be cured, following fault

rectification, by cycling the ignition ON-OFF-ON 3 times Refer to PDU

41 LH fresh / recirc. motor fault Harness / connector fault Servo motor seized or sticking Flap

seized or sticking Refer to PDU

42 RH fresh / recirc. motor fault Harness / connector fault Servo motor seized or sticking Flap

seized or sticking Refer to PDU

43 Cool air by-pass motor fault Harness / connector fault Servo motor seized or sticking Flap

seized or sticking Refer to PDU

43 Cool Air by-pass motor fault Harness / connector fault Servo motor seized or sticking Flap

seized or sticking Refer to PDU

44 Defrost vent motor fault Harness / connector fault Servo motor seized or sticking Flap seized

or sticking Refer to PDU

45 Centre vent motor fault Harness / connector fault Servo motor seized or sticking Flap seized or

sticking Refer to PDU

46 Foot vent motor fault Harness / connector fault Servo motor seized or sticking Flap seized or

sticking Refer to PDU

PDU DTC codes: not generally accessible with a generic OBDII code reader but linked

to the above may provide additional ‘Possible Causes’

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95 Sedan range interior illumination issues

1995> Sedan Range vehicles may experience fascia panel lighting and interior lighting malfunctions that can be caused by the back of the radio chafing on the fascia harness, In-Car Entertainment (ICE) system harness or the center console harness.

Some conditions found to be caused by harness chafing include:

^ Dimmer module fuse blows - shorted to ground.

^ No locate lighting.

^ No interior lighting.

^ Interior lighting remains ON - ground wire from module constantly grounded. 

^ Control panel illumination faults.

^ Hazard flasher light remains ON at all times.

^ Climate Control panel inoperative.



1. Remove the radio, switch pack and climate control panel as an assembly.

2. Check the harnesses running along the console and behind the radio for evidence of chafing.

3. If chafing is found, repair the wires, apply suitable protection such as 3M Glass Cloth Tape or convoluted tubing to the harness and secure the harness away from the sharp edges of the radio chassis and heat sink.

4. Check the operation of the systems listed.

5. Reinstall the climate control panel and the radio.

6. Check the operation of all systems.

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Jaguar TPS X300/XJ6 Tips

The throttle position (Jaguar Part No. JLM12074) sensor (a potentiometer or variable resistor) sends information via voltage to various other components in the car. One key thing being how much gasoline to inject into the engine. A general side of a problem is increased rpm's, problems with O2 sensors and shifting issues. This sensor is easily damaged during cleaning of the throttle body by carburetor cleaner entering the unit.

Back of  original TPS

The correct output voltage is .6 volts. You will need a digital volt meter to check with. It is possible for a small amount of adjustment due to some play in the size of the bolt holes which can be carefully enlarged to allow more adjustment.

A small file or a drill bit might be used to make the holes oval/slotted. This unit can be replaced without removal of the throttle body from under the car.  It maybe necessary to remove the oil filter to have room.

It should be noted that a dirty or sticky throttle body or weal throttle spring can also effect incorrect idle speeds.

A possible replacement part that can be adopted for the 12cyl. with minimal work is Ford part number 90TF9B989 or AC Delco part number 213-848 for a 4-cly 1993 Ford Mustang. More details HERE.

Adapted Ford TPS

See also Standard Motor Products Part No. TH417.


To test it, you’ll need to hook your voltmeter up to the TPS without disconnecting the harness.

Have the ignition on, with the Throttle Pulley at the idle position.  The voltage should measure between 0.58 and 0.62VDC. If not, remove the Throttle Pulley and loosen the three small mounting screws holding the TPS and rotate the TPS until the voltage reading is within range.

Now, rotate the Throttle Pulley and watch your voltmeter – make sure the voltage increases smoothly – any drops would indicate a break or other problem in the TPS or a jumping reading indicates a dirty wiper arm inside the unit indicating it needs replacement.  Do this at least a few times.

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X300/XJ6 boot light inspection

XJ6 boot lights

The inside of an X300 boot.  The cargo/boot lights were need of repair. The problem was broken power wire at boot hinge. Thanks goes to Gunnar.

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Changing Rear Axle bearings

Advice from Jag-Lovers forum

This is a DIY job - do each side one at a time, there's a spacer inside the hub that'll be different (most likely) on each side.
You will need to replace the stub axle nuts.  They have an locking insert in them and usually come apart on disassembly.
Mark the pivot bolt and lower control arm so you can reassemble keeping the rear tracking from changing.
I prefer to keep the hand brake cable attached to the hub. There's a union near the ''Y'' in the cable and I feed the
halves out of the lower sub-frame.
Do not let the hub flop down off the axle on it's pivot bolt, that can damage the hand brake cable.
Have someone (or something) press on the brake pedal when loosening the stub axle nuts.  They are TIGHT!
Originally, it is thought that Jaguar used a thread locking compound on the splines between the hub and stub axle.  Can be difficult
to separate if they've never been serviced from new.
Only special tools are a big socket and bar to loosen the axle nut, a brass drift and hammer to remove the old bearing
races and install the new ones.

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The Solar Sensor

The solar sensor is on the top of the dash, just behind the windscreen - here is an explanation of how it works:

In the morning or in the shade, when it's cooler, the a/c system comes on quietly and efficiently as expected when you start your car. If, however, it's been sitting in the sun, the a/c system comes on normally when the car starts but, after a few seconds, the blower system goes into ''high gear'' to cool down the cabin quickly.

Then, after the temperature has been reduced, it goes back into normal mode once again. It may not be apparent with your test methods but, as another poster has said, it's not like Jag or anyone else would install a piece that didn't have some purpose.

That sensor feeds info to the ECU that controls the cabin environment along with the thermostat and other sensors in the cabin. The "bump" detects high temps due to sunlight and tells the ECU that the sun has been shining bright into the cabin and to crank up the fan speed as soon as a cool air temp is detected in the airflow of the a/c. Once a more normal temp level is detected indicating that the super heated air has been evacuated, the system goes back into normal mode.

Jim B. writes, "It works that way on my car, anyway. I still recall the first time it happened after we only had the car for a week or so. It sat in the parking lot and was super warm. When the fan went into hypermode, it caught me by surprise as it was the first time it had done that. I thought I'd turned something on but it was doing it all by itself."

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X300 Key-Fob transmitter programming

Key-ring remote Battery changing:
Caution: To avoid disrupting the coding of the key-ring transmitter, battery change must be accomplished within two minutes.
Insert a screwdriver into the slot in the rear of the key-ring transmitter near where it joins the key ring and gently push it in so as to release the clip to allow the cover to pop open
Replace the two button batteries CR2016.

Existing key-ring transmitter Re-Programming X300:
Unlock the car with the key and press ether button three times at 1 second intervals
New virgin key-ring transmitter Programming:
Open the boot/trunk lid and drivers door. Switch on the ignition to position II but do not start the engine. Wait for the dash lights to extinguish. within 5 seconds of the lights going out, Rock the valet switch, in the centre console, 5 times. The system will chirp to indicate it has entered learning mode.

On models with seat/mirror/steering wheel memory functions, the first key-ring transmitter will be linked to memory 1, second to memory 2 etc
Press and hold the larger, lock, button on the key-ring transmitter whilst watching the Red LED and ether wait for it to stop flashing or for the system to chirp a confirmation it has got the signal. If the system doesn't receive any signals for 15 seconds, it will chirp twice and exit learn mode

To program further key-ring transmitters, rock the valet switch once. The system will chirp twice for remote number two, three times for number three etc, then press the lock button of the key-ring transmitter as above
When finished, wait 15 seconds for the system to time out and chirp twice, turn off the ignition, close the doors and boot lid.

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Replacing the automatic antenna mast

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Fluke on Voltage drop in cars

Electrical Automotive Troubleshooting

Diagnosing Voltage Drop

One of the most rampant electrical maladies showing up in automotive service bays today is the phenomenon known as voltage drop. Left unchecked, voltage drop causes countless unsolved electrical mysteries, especially when it infects the ground side of a circuit. It can also trick you into replacing parts that are not bad. The more connections and wiring a vehicle has, the more vulnerable the electrical system is to voltage drop. To contain electrical voltage drop, practice safe electrical service. This means measuring voltage drop before reaching any conclusions. "Voltage dropping" a circuit tell you when the circuit is too restricted to operate a component (motor, relay, light bulb, etc.) or operate it correctly. If the circuit is restricted, repair it and retest. If there is no restriction and the component still does not run or run correctly, then replace the component. In this example, if the water pipe completely collapses, water stops flowing, pressure drops to zero and the water wheel stops turning. Electrically, the same thing happens when a wire falls off or a connection breaks. Current stops flowing, voltage drops to zero. A starter motor would quit or a headlight would go out. Symptoms of voltage drop Often confusing and contradictory, electrical voltage drop symptoms vary according to the circuit's job and the severity of the voltage drop. inoperative electrical parts sluggish, lazy electrical devices erratic, intermittent devices devices that work sluggishly or erratically during periods of high electrical loads excessive radio interference or noises in the radio damaged throttle or transmission cables or linkage repeated throttle or transmission cable failures damaged drivetrain parts engine or transmission performance complaints no-starts or hard starts high sensor or computer voltages erratic engine or transmission computer performance false trouble codes in the memory of any on-board computer premature or repeated A/C compressor clutch failure. This symptom list brings up several points. Visual inspections miss most cases of electrical voltage drop. You usually can't see the corrosion inside a connection or the damaged wire that is causing the problem. Ground-side voltage drop, a commonly overlooked cause of electrical trouble, can cause most of these symptoms. Any circuit or component is only as good as its ground. The more sophisticated electrical systems become, the more important their grounds are. The number of electrical components has increased rapidly and most do not have separate ground wires. Instead, these devices are grounded to the engine or body. Rust, grease, vibration and/or careless repairs often restrict the circuit from the engine/body back to the battery. Many components such as engine sensors share a common ground. Therefore, a bad ground complicates diagnosis because it affects several components at once. Some shop manuals and diagnostic charts or fault trees recommend checking grounds last. In reality, it is much quicker to check ground circuits before you climb that fault tree. It's quicker and smarter to routinely check a circuit's voltage drop than it is to memorize long lists of symptoms. If experience has taught us nothing else, it's that chasing symptoms is no substitute for routine and thorough voltage drop testing. Experience has taught us other reasons to check voltage drop first. Voltage drop, usually on the ground side, causes inaccurate or bizarre voltmeter readings and oscilloscope patterns. Moreover, when you connect a voltmeter or scope to a system with bad grounds, the test equipment itself can create a good substitute ground. This can be frustrating: as long as your equipment is connected, the circuit works and you can't find anything wrong! Basic procedures Whenever an electrical problem gives you fits, take a deep breath and think of the basic electrical building block, the series circuit. Drawings 1 through 7 show basic series circuits. No matter how complicated a system is you can always simplify it into mini-series circuits. Then, inspect each circuit for voltage drop. Also, relate electricity to water flowing through a water circuit. Water pressure inside the reservoir pushes gallons of water through the pipe. The water turns the water wheel and then flows back into the reservoir. In an electrical circuit, electrical pressure (voltage or volts) pushes electrical volume (current or amps) through the circuit, operating a load. The load may be a computer, a motor, a lamp, a relay, or other device. In the water circuit, the water uses up most of its energy turning the water wheel. Water continues flowing toward the reservoir, but it flows at a lower pressure. Likewise, electrical pressure (voltage) is used up operating the load. Therefore, voltage falls to about zero on the ground side, but current keeps flowing toward the battery. Because the voltage in a healthy ground circuit should be about zero, some technicians call it ground zero. A kinked return pipe restricts water flow back to the reservoir, slowing down the water wheel and causing a pressure reading on the return side of the wheel. Likewise, ground side voltage drop hurts load performance and causes a voltage reading at the ground side of the load. Resistance—Restriction When you think of excessive resistance, imagine a dent or kink that is restricting water flow through a pipe. Common sense should tell you that a kink anywhere in the water circuit (supply side or return side) restricts water flow, causing the water wheel to slow down or stop turning. Excessive resistance has the same effect on an electrical circuit. Bad connections and broken or under size wires act like a pipe with a kink, restricting current flow. Like the water circuit, restricting current flow anywhere — hot side or ground side — hurts the performance of the load. The effect on the load is hard to predict because it varies with the severity of the restriction. For example, the motor in a restricted circuit may stop working or just run slower than normal. A restricted circuit can cause an A/C compressor clutch to slip and prematurely burn out. A computer on a restricted circuit may shut off or else work erratically. When corrosion, loose connections or other types of resistance restrict a circuit, volts and amps both drop. If volts drop, amps drop too. That is why when you find a voltage drop in a connection or cable, you know the connection or cable is restricted. Look at the water circuits in our drawings and remember two critical points. First, a free-flowing ground side is as important as a free-flowing hot side. Second, a ground side restriction is the only thing that causes voltage readings greater than 0–0.1V in any ground circuit. A completely collapsed return pipe stops water flow, stalling the water wheel and causing a system pressure reading at the return side of the wheel. Likewise, a broken ground wire totally blocks current flow, shuts off the load and causes the ground side of the load to read system voltage. Voltage drop tests Electrical voltage drop varies according to current flow. Unless you operate the circuit so current flows through it, you can't measure voltage drop. Because an ohmmeter's battery can't supply the current that normally flows through most circuits, ohmmeter tests usually can't detect restrictions as accurately as a voltage drop test. Open-circuit problems such as broken or disconnected wires or connections stop current flow. After you fix an open circuit, switch the circuit on again and check for lingering voltage drop. Until you get current flowing and check the circuit again, you can't know if the entire circuit is healthy. Although resistance-free connections, wires and cables would be ideal, most of them will contain at least some voltage drop. If your manuals do not list voltage drop values, use the following as maximum limits: 0.00V across a connection 0.20V across a wire or cable 0.30V across a switch 0.10V at a ground Because most computer circuits operate way down in the milliamp range, they don't tolerate voltage drop as well as other circuits do. Note that a milliamp is one-thousandth (0.001) amp. The recommended working limit is 0.10V-drop across low-current wires and switches. Testing low-current circuits also requires a high-impedance (10-megohm) voltmeter. A low-impedance voltmeter may load a low-current circuit so much that it gives an incorrect reading or no reading whatsoever! Most professional-grade digital multimeters (DMMs) have 10-megohm input impedance. Using a DMM is the fastest way to accurately measure voltage drops. If the DMM you own does not have autoranging capability, use a low-voltage (0-1 V) scale for voltage drop testing. Remember that test lights are not accurate enough to diagnose electrical voltage drop. Quick ground tests Because ground circuit voltage drop can cause most of the symptoms listed earlier, consider adopting this new work habit: test grounds first! Before you do a tune-up, check out electrical problems, or test a starting, charging, ABS or air conditioning system, routinely test the engine and body grounds. Connect your DMM between the engine and negative battery terminal. Safely disarm the ignition and crank the engine for a few seconds. If the voltage drop is excessive, repair the engine ground circuit and retest. Note that on some distributorless ignition systems, the simplest way to prevent the engine from starting during the ground test is to pull the fuel pump fuse. Next, connect the DMM between the negative battery terminal and the vehicle's firewall. Then start the engine and switch on all the major electrical accessories. Too much voltage drop? Then fix the body ground and retest. Once engine and body grounds are within limits, proceed with your diagnosis. Do not be surprised if fixing these grounds solves the car's problems. The fact that a vehicle passes the body ground test does not mean you can safely ground your voltmeter wherever you want. Some technicians have run themselves in circles for hours because their voltmeters were not well grounded. For safe electrical service, make yourself a 20- or 30- foot jumper wire with an alligator clip on each end. When you have to test an electric fuel pump, lighting system or ABS computer in the rear of the vehicle, ground your DMM to the battery with the jumper wire. Computer ground kinks Because computer circuits operate on such low current, the standard ground tests may not reveal a marginal ground on an on-board computer. Before you condemn any on-board computer, check its grounds first. Operate the computer system and backprobe each computer ground terminal. If you measure anything greater than 0.10V, trace that ground circuit and locate the problem. Sometimes, computer grounds are connected to a spot where they are easily disturbed or prone to corrosion, such as a thermostat-housing bolt. Computer connector terminals also can corrode. Removing the connector and spraying the terminals with electrical cleaner may be all it takes to eliminate the voltage drop. Experience shows that as little as 0.30V on a computer ground terminal can cause trouble. Try pinpointing that with a test light! Poor computer and/or sensor grounds can cause higher-than-normal sensor voltages and false trouble codes. In many cases, the bad ground prevents the computer or sensor from pulling a voltage signal down to or near ground zero. Sure, accessing the computer to check grounds may be a hassle. Nevertheless, mistakenly replacing expensive sensors and computers is a bigger hassle. Connect a DMM across part of a circuit and it directly reads the voltage drop across that wire, cable, switch, or connection. Here, one DMM would display the voltage loss between the battery and the load. The other would show the voltage loss from the ground side of the load to the battery. Body ground gremlins Keep your eyes peeled for missing body grounds. If someone else worked on the vehicle, he may have forgotten to reconnect body ground wires or cables. Remember that when the body ground is restricted, current tries to find another route back to the battery. The easiest alternate route may he through the transmission shift cable or the throttle cable. Not only can this current weld the cable together, it also can pit or erode bushings and bearings inside the transmission. If you find the insulation on the body ground wire is burnt or blistered, you can bet that starter current overheated the wire. When the engine ground is restricted, starter current tries to return to the battery through the body ground circuit. Experience shows that if the body ground circuit can handle the current load, the customer may not notice the problem right away. Under periods of heavy current flow, a restricted body ground may hamper or shut off a component. For example, turn signals have been known to stop blinking when the driver steps on the brake pedal. Testing confirmed that a restricted body ground choked off the turn signals. The ground could not handle current from the turn signals and brake lights at the same time. Safe service Practicing safe electrical service helps you solve electrical problems quicker and more profitably than guessing and swapping parts. Put your DMM to work wiping out electrical voltage drop today. It is the responsible thing to do.

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Check for voltage loss in jaguar wiring

The process takes only a small amount of time to test, more time and money to fix. See this help section to explain the process.

Here is an article on the process.

Voltage loss calculator

What is terminal Fretting?

Alternator voltage drop

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Secondary List of X300 issues some overlap

Used Jaguar X300's - Common faults.
Back Axle noise, especially on the over-run.
Don't be tempted to buy a car with any appreciable noise on the 'back end' You may have been told that the noise is due to a worn wheel bearing but this often not the case. Mostly, worn differential bearings are to blame.
Repair is expensive in both terms of parts and labour and there aren't many mechanics that can (or will) do the job. Finding a second-hand differential unit that is genuinely quiet is difficult, and the last thing you'd want is to spend a lot of money in having a used Diff. fitted only to find it is also noisy and the assurance that it is 'guaranteed' is worthless. The only way to buy a used unit is to stick to what you can test drive before buying and make sure that it is that unit you end up with. A new or reconditioned differential unit will set you back a long way, possibly costing half of what a car is 'worth', plus the labour of removal/refit.
Note that the labour element of this job is unpleasant to undertake, whilst seized bolts can hinder the job further. In my experience, the labour cost of removal and refit of a diff. unit is somewhere around £400 - £500, and that is without the supply/ repair of the diff. I have got 'lucky' in finding a used diff. unit that proved to be quiet but the total cost of buying it and having it fitted exceeded £800, not good if the car is 'worth' only £2000.

Alleged 'Spongy' Brake Pedal
The X300 braking system is quite different to that fitted to the XJ40. The XJ40 has a real 'drivers' pedal, moving very little before the brakes are being applied. The X300 (and XJ8 for that matter) have much more pedal travel before the brakes actually come into play.
I have heard XJ40 drivers make comments about 'Sponginess' of the X300 / XJ8 brake pedal and making an incorrect assumption that there is 'something wrong with the brakes' on X300's or XJ8's. I even had one MOT tester try to fail a car on 'no reserve footbrake travel' but soon educated him on these differences by inviting to speak to a Jaguar Agent and giving him the chance to try another car.
The plain fact is that the X300 / XJ8 has more pedal travel than XJ40's and some other makes. When someone claims to have found a 'brake fault' it is often due to them being unfamiliar with the model.
 
Digital Dashboard Clocks
I only see around 5% of cars with this clock actually working. There are replacements available from E Bay or similar, costing £35 - 70 plus fitting which can be DIY, although there is quite a lot of work involved removing trim etc. I have heard that the clock can be repaired by simply sliding in a piece of cardboard behind the PC board connection in order to tighten it up but I have not tried it to date.
UPDATE -
I found the description of this repair kindly posted by someone on the excellent Jag Lovers website. Click this link - Jag Lovers - Dashboard Clock

Oil Pressure readings low or Zero and Oil light coming on
This is a common problem, especially on older or higher mileage cars. It can be alarming as it often denotes an engine which is about to expire on other makes. Worry not. I have had several cars that have shown zero Oil pressure, normally just after warm up. The X300 engine is 'bombproof' and I have never seen one quit in such circumstances. When checked out, it always has actual Oil pressure if checked with an in-line (mechanical) pressure gauge. The cause of the errant 'Zero' pressure indication is the electronic sensor which fails to work at certain temperatures when close to the end of its useful life. The cure is to fit a new or even a used sensor. This is a relatively easy thing to do although it is hard to get at.

Central Locking and Alarm Key Fob not Working
Key fob transmitters have a hard life and do wear out. It may be that new Fob Batteries (there are two, part number 2016) will bring the fob back to life. If that is the case then you are lucky. We often see fobs that have only one battery fitted by a previous owner and its not surprise that the fob does not work. Again, if that is the case with your fob you might get lucky, because....
A replacement fob costs around £120 plus VAT from Jaguar and then it must be adapted to the car. A secondhand one can be bought and adpated to suit the car if you can find one that works.
Cars that have 2 servicable fobs are rare, mainly because the first fob packed up and a previous owner moved on to using the second one. To be fair, getting one working fob with a car that has covered 100k miles is a bonus. Two working fobs is almost unheard of! If you haven't got a working fob at all and don't want to replace it, you don't have to buy one at all. The Alarm will be armed and disarmed by using the key to lock the doors. When opening the doors you have to get the key into the steering lock and switch on the ignition pretty quickly to stop the alarm horn sounding. See the Driver's handbook for more on this.
 
Boot opening (external) switch not working
The button used to open the X300 boot from outside the car operates a small switch. This can fail, although most often the wiring that crosses the boot hinge will have become stiff and broken through. It is not expensive to fix the problem but like many electrical jobs it can soak up a lot of expensive diagnostic time. It is always much cheaper to use the boot button inside the car, or the key from outside and leave well alone!

Heater not supplying hot air
In just about every case, this is due to the failure of the electric circulation pump, fitted on the NSF inner wing. Replacements are not cheap from Jaguar although a used one might be good. Specialists like David Manners can save you money on a new one.
NOTE! If your car is LPG converted a failed heater coolant pump can cause all sorts of problems because the LPG system relies on hot coolant being supplied by the heater circuit. If it doesn't get that, the LPG system will not perform properly.
Another cause of heater failure can be Air Locking, especially if the air is trapped in the heater matrix. This problem is much that same as Air Locking in a house radiator and has the same cure. There are various methods for 'bleeding' the air out. In extreme cases we've had to raise the front of the car whilst bleeding air out of the matrix.
If you bleed the heater matirix successfully only to suffer the same problem later on, start looking for a coolant leak before things progress to a more serious level.

Screen Washer Pump not working
Most often the pump itself will have failed. It is not easy to get at, requiring the removal of the OSF inner wing liner. Jaguar charge £47 inc. Vat for a new pump although note that many types of Ford screen wash pump can be made to fit. I have bought these at £2 each from a breaker. If you go down this route, take some of the wiring and the connecting plug along for the ride. Often these differ whilst the pump is similar mechanically.
Other causes can be simple blocking of washer nozzles and pipes or failure of the in-line non return valves.
There is a pictoral 'how to' item on Screen washer pumps on one of our other Jaguar pages - Jaguar faults

Rear Bumper Top Face Bright Trim.
These are often dented by careless folk dumping heavy items on top of the bumper before opening the boot. The top trim is not chromed steel as many expect, but high quality stainless steel. A new replacement trim costs £165 plus Vat from Jaguar. They are held on by all manner of awkward clips which break easily. Also be aware that the bumper has to be removed before replacement can commence, something which brings its own problems in terms of seized bolts and broken plastic.
Add the labour cost to the cost of the replacement trim and you could easily spend £300 total. If you are lucky and the dent is not serious, it is possible to remove the trim and carefully roll out the dent. For best results, ask an experienced panel beater to do this for you – NEVER use a hammer on the back of the trim without a sandbag on the other side or you'll end up with a worse dent in the other direction!

Rear Windows not working
This is another common X300 problem which is often due to simple lack of use. The motor is not too hard to remove and may respond well to freeing oil and TLC. You can plug the motor back in when it has been removed and check it for operation using the door switch (with ignition on) but mind your fingers!

Rear Shock Absorbers – Rattling noises on the back end………
This problem is often passed off or misdiagnosed as loose exhaust mountings, items moving in the boot or perhaps a loose rear bumper. If the noise occurs most often after going over a pot hole, it is more likely that the mounting bushes and bearings of the rear shock absorbers are to blame.
If the shocks themselves look old it is often a mistake to have them re-bushed. The only way to deal with this is to fit complete new shockers or have then fitted. The Jaguar replacement items are very expensive although David Manners supply a new pair (and I'd only recommend fitting a pair) for £127 delivered.
Don't be tempted to buy cheaper items as the top of the shocker shaft can snap right off during a good jolt, meaning the job must be done all over again. Removal and refit is, like the rear differential, not a fun job. Labour cost is around £150 a side (as long as none of the bolts shear off when being undone) making the total cost of a pair of rear shocks around £450.
I do not recommend DIY for this job. The good news is that the handling of a car with worn and noisy rear shock is dramatically transformed by fitting new ones!

Aerial Mast replacement
Often these are broken, damaged or simply seized. If seizure is the problem they do not normally retract or extend properly. The major cause of seizure is lack of regular cleaning of the mast by the previous owner or driver. As prescribed by Jaguar, the mast should be cleaned every 2 weeks or so using WD 40 and a soft cloth, wiping in an upward direction only. This stops the dirt from being pushed into the joints of the mast. If the mast has to be replaced beware that new ones are not cheap - £47 from Jaguar.
 
Air Conditioning not working.
By far the most common used X300 fault. The cause is often no more than a lack of use by the previous owner(s). As prescribed by Jaguar, the Air Con, should be turned on every 2 weeks or so to keep it maintained, Winter or Summer. The reason for this is simple once Air Con is understood;
Air Con. has many mechanical parts that require lubrication, bearings, seals and so on. The Air Con. system contains a gas that tends to remove ordinary mineral based oil or grease. To get around this problem a special lubricating oil formulation is added to the refrigerant gas. This oil only circulates to where it is needed when the Air Con. system is working. If this oil is not circulated, mechanical seizure can result.
Secondly, the many seals that keep the gas in the system will tend to dry out and shrink if they do not get a regular supply of this special oil. If the system isn't used regularly the seals will shrink and the gas will escape, leaving the system inoperative the next time it is called upon. As a result of this there is no special oil left in the system either. You will hear many people speak of a car's system needing a 're-gas' but this is often unsuccessful. Once those seals have shrunk to a certain level they will not come back to useful life and the gas just put in will leak out within a few days. A large repair bill then looms.
It is easy to spend £1000 or so on a Jaguar Air Con. System that has been neglected. On older cars it has to be judged as to whether it is worth doing this. If you are lucky enough to have Air Con. working in an X300 or any other car, look after it by running it every 2 weeks or so. It really is a case of 'Use it or lose it'.
Note that cars fitted with 'Climate control' only but having no Air Con, system are actually preferred by many – If Air Con. isn't fitted, it cannot break!
 

Cars that will not allow 'Drive' or Reverse to be selected from a start
If the brake light bulbs (or the circuit that feeds them) do not work, the gear selector interlock will not release from the 'Park' position when the brake pedal is pressed. It can take ages to select a gear in such a case. Also note that the Brake light switch itself can be faulty or out of adjustment, causing a similar problem although the bulbs are both good and the circuit is working.
 
Front and Rear Brake Discs - Warping and Wear
Wear is clear enough to diagnose. When the brake discs become too thin they need replacing. They are checked on MOT but sometimes a 'borderline' case will be let through the MOT, only to be well below par after a period of frequent use later on. Only replace them (or have them replaced) in pairs, 2 front or 2 rear, and with new pads. If you are DIY'ing, make sure the protective coating is cleaned off the discs before fitting the pads.
Disc Warping will manifest as 'pedal bounce' and may be felt through the steering, especially in the case of front discs. Replacement as prescribed above is the only realistic cure.

Petrol Cap drain blockage and Water Contamination of Fuel
Owners still using Petrol to run their cars get to see the petrol filler every day or two but those running on LPG rarely see it!
The filler drain hole and its filter are both prone to blockage by leaves and other debris, causing the filler to collect water. This is really undesirable. The water can leak into the Petrol tank under the submerged cap and cause you all manner of problems later on.
Check that your filler drain is clear. If it isn't, take out the filter and clean it. The drain pipe itself can be unblocked with a length of stiff wire. Test it out afterward with a little water and remember to keep an eye out for the next blockage (most likely in Autumn). For pic see our other page on Jaguar faults


Car Wash Damage to Paintwork
Easy to spot and often worse on top surfaces, roof, bonnet and boot lid. The laquer finish is 'fogged' (scratched) by the coarse nylon brushes. Often the damage cannot be polished out. Avoidance is easy - Never put your X 300 through a car wash!

Cars that Idle Eratically or Stall at Junctions
The first thing to check for is any air leakage after the air mass meter. The rubber 'Bellows' fitted to the inlet manifold is the main area to concentrate on. The second thing is much more subtle - Have you recently changed the spark plugs or had them changed?
X300's are notoriously sensitive to spark plug resistance. If this is incorrect, the ignition timing can oscillate between high advance and retard values, making the engine speed change dramatically. This makes the engine idle badly or stall. Some engines may not even start at all. If you find this just after changing the plugs, put the old ones back in until you have sorted out what is wrong with the new ones.
 
Replacing Oxygen (Lambda) Sensors
These are a consumable item and have a finite life. Testing or replacing them can be difficult. We came up with the X300 Lambda Connection Modification to make life easier.

Siezed Front Brake Calipers
A lot of X300 calipers sieze, we have replaced many. Dissasembly shows the cause to be split rubber piston seals which allow road water and salt in, resulting in corrosion. Almost without exception, the blame lies with the last but one person to change the pads, having used some unsuitable instruments and little care. The seal is damaged then, and in time corrosion takes its toll on the unprotected piston. Next time new pads are fitted, even by a careful person, the corroded portion of the piston is forced back into its cylinder and it will eventually sieze up.

Replacing the Fuel Filter
Take great care when undoing the union nuts to the filter - Often the fuel pipes are corroded and fall into a pile of dust. If that happens it's best to go back to good pipe both sides and splice new sections in, but it would be unwise to do this with worm drive clips and bits of fuel hose. Get same diameter push-on hydraulic or air connectors, they are an absolute doddle to fit and no risk of leaks as they are designed for far higher pressures than present in Jaguar fuel delivery. Best to check that the parst you are buying will be fuel proof! For the missing pipe you can use new plastic fuel pipe. At the filter end(s) things might be easy or complicated, depends on the conditions of the union nuts. If they are scrap then you could replace them or go for a filter with different connections that can be bought to match.

Replacing the Throttle Position Sensor (TPS)
The TPS is driven (rotated) by a tang much like the end of a standard screwdriver. Because of that it can be wrongly installed, 180 degrees out.
I have seen one that read over 4.5V at idle, the result of the fitter rotating it before putting the bolts in. To ensure correct installation you should see around 0.5V or less than 10% on a scanner at idle. If you don't have a scanner you can check the voltage on the green wire with yellow bands (TPS signal wire to ECU) using a multimeter. The engine does not have to be running to do this check (it is better that it isn't!), just have the ignition on, look for 0.5V at idle position and around 4.5V full throttle.
Just to finish this off, one should not expect to see 0V at idle (that shows that the circuit is dead) nor 5V at full chat. Those clever backroom boys left margins at both ends (a) to show the ciruit is live and functioning as described above, and (b) for the avoidance of increasing (over time, with age and corrosion)) resistance potentially messing up idle values. It is a lesson that Ford learned a while ago and carried over.

Engine Cranking - No Start.
During cranking, observe the tachometer - It should show around 200 RPM. If if doesn't, the Crank Position Sensor (CPS) is likely to be at fault. This test has been demonstrated not to be definitive though, the sensor may still be bad even if the tacho. shows cranking RPM. The sensor is easy to get at, being mounted close to the front Crankshaft pulley on the fornt of the engine. The worst you will encounter are siezed mounting bolts. If the sensor has done more than 50K miles or so, replace it anyhow - They do not last forever and will catch you out one day.
The X300 Crank Sensor
Rough Running after Plug or Coil Changes
If the coil wires for cylinders 5 and 6 on an AJ16 are mixed up (easily done) your previously smooth running pride and joy can be turned into something akin to a bag of spanners. I've seen one of the cat.s glowing red hot on a car bought here for diagnosis as the fuel was not being burned in either cylinder, but it was in the cat. The wiring for coil 6 often had a ring of yellow tape around it (even Jaguar suffered this problem) but with age the tape can fall right off, it is then very easy to mix the two. It's really good practice to replace it (whether the tape is present or not) with a tiny cable tie which should last the life of the car.

The Yellow tape marks the wiring for Cylinder / Coil 6. Noisy Fuel Pump? Is it about to fail?
The pump may indeed be about to fail, but let me put a slightly different slant on it;
If the pump were struggling to supply fuel due to some kind of restriction (say a blocked fuel filter), then you'd expect it to be noisier in operation because of the increased load placed upon it. You might then expect it to fail as a result of that increased load.
It might be prudent to check the entire fuel delivery/return system for restriction before diving in to fit a new pump which, after all, is as likely to be noisy if there are other problems.


X300 Gearbox Warning Lamp

There are few things on an X300 that cause more confusion and misunderstanding than this one.


The most common reason for this lamp to be illuminated has nothing to do with the Gearbox at all.
The warning is often generated by an engine stall. It simply means that the engine management system knows that something does not add up (and it wouldn't if the engine isn't running!). The illumination of this lamp merely indicates that the gearbox has been limited in is operation. It does NOT mean that the gearbox fluid is low, nor does it mean that the gearbox is malfunctioning or has suffered any damage.
If the lamp has been illuminated as the result of an engine stall, it will clear (turn off) if the engine is stopped for a minute or so, then restarted. Normal service will then be resumed, at least until the next engine stall. You'll need to progress by focussing on why the engine is stalling, not by worrying if there is anything wrong with the gearbox.


X300 Poor Idle Quality - Exhaust Valves Sticking Partially Open
This phenomenon was well known to Jaguar, but not their fault. The use the vehicle was put to was a major factor, along with fuel quality. Click HERE to read a page from the service bulletin.

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