A few months ago my 2005 X350 3.0L V6 went into limp mode with the well known Engine Systems Fault, Park Brake Fault, DSC Not Available. A friend with diagnostic software advised it was the Throttle Position Sensor (TPS) causing the problem. A sourced a new aftermarket replacement unit from the USA and installed it. Cleared the faults codes with a basic ELM327 scanner and Torque Pro but problems persisted. This time the error code P0222 showed up. This fault is described as, Throttle / Pedal Position Sensor / Switch "B" circuit Low Input. I was advised by an independent Jaguar workshop that the problem could be in the position potentiometers located in the Accelerator Pedal Box.

I commenced removing this box as per the instructions in the manual and have disconnected all the electrical connections. However I need advice on removing the accelerator pedal height adjustment drive cable. It appears to be held onto the drive motor via a plastic housing with 3 latching lugs. All of which would need to be depressed simultaneously to free the housing from the motor. See attached photos.

Any advice would be gratefully received.

Regards
Paul

X350 Accelerator Pedal Box

X350 Accelerator Pedal Box showing drive cable connection

 

Upon closer inspection I found that the height adjustable cable was connected to the brake pedal height adjustment via a worm gear arrangement.
As I was not keen to meddle with this I removed the pedal and potentiometer housing from the accelerator mounting bracket. It was only held in by a pin and circlip at the top and a swivel bolt at the bottom.
I now have the electronic assembly on the bench ready for testing.
See photos below.

Regards

X350 Accelerator Pedal removed from vehicle

X350 Accelerator Pedal Sensor Housing

 

Hi Paul,

I had this problem caused by p0121, which resulted in the many fault codes you saw. I replaced the TPS, with a new one, and then immediately after had P0222. When I tested the 'new' TPS for resistance (OHMs) across the whole range of the sensor it had a dead spot. When I tested the old TPS then it's OHMs were fine right across the whole range. So it might be worth checking that your new sensor is working properly before you start replacing other items like the Pedal housing that you have now removed.

Thanks,

Chris

 

Does anyone have, or know where I can find, the typical resistance values for the potentiometer tracks in a 2005 X350 V6 accelerator pedal box.
This pedal box may also have been used in the S-Type of that era.

Regards

 

Thanks Chris

I will test both the old and new TPS across their complete range to check for "dead" spots.
Will let you know how I get on.

Regards

 

I'm not 100% sure but it looks to be a TPS not APP problem. Still, no harm checking the APP values if you can.

It could be wiring/connector, doesn't have to be the actual sensor, though the sensor strikes me as more likely.

 

Agree with JagV8, this fault code you have is related to the TPS. The TPS has two tracks in it. The fault codes usually throw when there is a fault on one of the tracks. P0121 is on circuit A track and P0222 is on circuit B track. It can also be an electrical connection issue usually at the TPS connector itself.

I'll try and find my TPS pin and wiring layout so you can test the resistance. I worked out what wires you should test for resistance but I can't remember them off the top of my head !

Thanks,

Chris

 

I checked all the carbon resistance tracks in the accelerator pedal box for continuity and confirmed they all had some resistance value.
Then increased the pre-tension on the wiper arms slightly, in case they had lost some of their original tension.
Gave the tracks and wiper arms a good squirt with electrical contact cleaner and re-assembled the whole thing.
The hardest part was getting it back in the car, a real PITA. I'm getting too old to screw my body up underneath the dashboard.
Once reinstalled I started the car and reset the fault codes but P0222 was still there.
Also Engine Systems Fault, Park Brake Fault, DSC Not Available were still displaying on the dashboard.

I will now go back to the TPS and its wiring and check it out more thoroughly as both JagV8 and JX350 have suggested.

Regards

 

Also Engine Systems Fault, Park Brake Fault, DSC Not Available were still displaying on the dashboard.

May be due to bad earths behind headlamps

 

Hi Paul,

You'll have to take off the TPS to test it fully.

I've just found my other post related to these fault codes and here is the pin layout of the TPS.

Orange - Constant 5 Volts
Red - TPS Signal wire
Yellow - Idle Signal wire
Black/Green - Ground

These are the readings that I got from my working TPS and taken from my other post:
Orange - Constant 200 Ohms when connected to Black/Green or another ground on the car body - even when sensor is moved throughout it's range.
Red - When connected to Black/Green wire I get 5 Ohms when closed, up to 201 Ohms when fully open. The Ohms changed smoothly when moving through the range.
Yellow - When connected to Black/Green wire I get 87 Ohms when closed, up to 211 Ohms when fully open. The Ohms changed smoothly when moving through the range as well.
Black/Green - Ground

To test the resistance you should disconnect the electrical connector and remove the TPS. Simply connect your multimeter pins to the correct pins and slowly rotate the inner part of the TPS. There should be no dead spots across the range and you should see a steady OHMs.

Thanks,

Chris

 

Hi Chris

After a break over the Christmas holidays I decided to go back to the shed and have another crack at solving this problem. It gets terribly hot in there at this time of year but I did manage to install a 2 post hoist with the help of my grandson, however I digress. I took my original TPS and measured all the resistances as per your schedule above. I found that my readings were consistently higher than yours by a factor of 10.

These are the resistance readings for the original TPS:
Orange - Constant 2.17KΩ to Black/Green through full range
Red - 40Ω to Black/Green when closed, 2.17KΩ when fully open
Yellow - 960Ω to Black/Green when closed, 2.3KΩ when fully open
Black/Green - 0.3Ω to ground (could be wiring resistance or DVM offset)

I then decided to remove the new, aftermarket, TPS from the throttle body and test its resistances.
I found that the overall resistance was higher, ie 3.82KΩ compared to 2.17KΩ for the original TPS.
Then, to my surprise, I discovered that the Yellow connection was completely open circuit!

At this point I decided to put the original TPS back in the car and the fault had disappeared.
I was able to reset the fault codes and the engine appears to be behaving normally.
The only light left on the instrument cluster is the red MIL light. Hopefully this will disappear when I take it for
a decent test drive tomorrow.

I assume that that the original fault may have been caused by a wiring problem that has been fixed (temporarily) by me
moving around the various wiring looms and connectors. This will require further investigation.

I will let you know how the test drive goes.

Regards,

Paul Lucas

 

Hi Meirion1

I checked the earths behind the headlamps and found that the original earth studs had broken off and been replaced by bolts drilled and mounted through the bulkheads.
I checked the resistances to ground (chassis) and found they were both good.
I did however find another problem. You can read the details in my reply to JX350 above.

Regards

Paul

 

Hi Paul,

Great news that you've fixed it. Like you, I purchased a new one only for it to be faulty. After put in the old one back I also cleaned the connections and reseated the connector and I have not had this problem since. Often these issues are caused by the connector or the connections.

If the red MIL light is still on then it should mean that the car has a fault with something still. Usually when I clear any fault codes then the MIL light goes out. I would recheck for fault codes again incase.

Thanks,

Chris

 

Hi Paul

Thanks for your reply.

I have always been suspicious of non Denso TPS and have an used

TB with Denso TPS on hand in my stock of spares.

I hope that you have fixed the problem permanently.

 

I took the X350 out for a drive today, for about an hour, without any sign of a problem.
The MIL light from the day before had disappeared as soon as I started the engine.
Hopefully the problem is gone but I will need to keep a close eye on it.
I might invest in a good spare throttle body with TPS.

Thanks for all your suggestions and encouragement.

Regards

Paul

 

A supply of spare known to fail parts on hand, can be a real time saver for quick repairs.
Especially with more than one Jaguar in the garage.

 

Guys need help

Random cut out of 2005 xj350 diesel

Them leave for few mims , starts up and them ok for 5 min. Them repeat

Tps ?

No eml

 

Hi Khalid
Try scanning for fault codes to give us a clue.

 

Hi thanks for getting back to me . Yeh will pop ot in tommorrrow . Just am not getting any eml hence worried it won't even give me a code .

have checked the esrth straps and they seem fine . Hoping something simply like the throttle sensor