Afternoon,


Keeping it short; After a successful weekend in a muddy field at Le Mans with no major car drama, the long drive back to Zürich wasn't so brilliant.


About 2 hours in, while climbing a hill with CC on, my 2002 XJR-100 started feeling a little odd, ever so slightly hesitant, but still subtle enough to be put down to road surface/wind etc.

On the other side of the hill, suddenly the amber and red dash light came on informing me that Trac and ASC aren't available and also the dreaded Restricted Performance.

I hard shoulder it, set up the warning triangle and give the car a once over. Obviously upon opening the bonnet I'm expecting smoke/oil/actual gremlins, but everything seemed normal, underside too.

I restart the car and all lights are off and she drives off fine, albeit still not feeling 100%. At this point I'm still 3 hours outside of CH, and 4 away from home.

Thankfully for the rest of the trip she doesn't have another spasm, stopping for breaks more than normal and testing the pull from the French toll booths, all normal. I must add that I kept CC and Trac off for the remainder of the drive.

After some forum hunting I see the TB assembly is worth a gander, so I strip the intake down this weekend to look. Everything looks clean, but I cleaned the TB anyway. Upon doing so I noticed some weird (perhaps normal) behaviour from the TB, the video below will show better. May somebody please tell me if this is normal?




The WOT noise and the switch off 'procedure' seemed most odd to me.

I have ordered an OBD II scanner, so I can not help with codes as of yet.



Any advice gratefully received,
- Richard

 

Nothing to see here.....seriously, all AJ27 throttles make whining noises at some point - I'd be more interested in any posted codes on the car's memory.

By the way, didn't catch any coverage but listened to a bit of Radio Le Mans, sad to hear of a driver death in one of the Aston's, but that's racing. I used to go but more interested in the retro version now, I wish it was every year - did the Audi e-tron's do the business, more like tech wizard trucks now....diesel's now have a place in motor sport!

 

So, following on from my 'blip' driving back from Le Mans I had the car on axle stands for a little once over.

As a matter of course I replaced the air and fuel filter. A winter in CH really cruds up ones air filter.


I had bought a D900 scanner, with a view to read and codes and see what the cause of my Le Mans blip was.

Remember when I parked the car up initially I had no lights on on the dash.

I had the TPS and MAF unplugged as these were being cleaned with contact cleaner. I tried my scanner, ignt on, of course turning ignt on to the system check flashed up TRAC/ACS n/a as expected.

Unfortunately the D900 scanner does NOT work with these Jags, it just kept on crashing when starting the DTC read, also could not connect for Live Data View. I have added this scanner to the black list.

As well as cleaning the TPS and MAF, I removed and cleaned all four wheel sensors. The rears were particularly crappy:

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After some cleaning:

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I cleaned the connectors up as well and re-fitted everything.


The car sat for another week and I've just started her up. Unfortunately now the CEL light is on, with the same TRAC/ASC messages cycling.

As I mentioned, the CEL was not on before I started this clean up operation.

Would I have turned the CEL on by turning the ignition on with the TPS unplugged?

I have done a hard reset, both naturally the CEL light is still on. The car drives great, both pre and post reset.

I realise I need a functioning reader. Unfortunately my only laptop is a Mac, so Windows based readers are not that viable for me. I have been looking at a Kiwi PLX WiFi unit, with the idea to connect to an iPad, has anyone any experience with this on an X308? The unit (and necessary app) is a lot more pricey than the D900 unit I failed with, so obviously want to be more sure this time. Live data is the selling point for me.


If you gentlemen have any ideas/suggestions then I will be most grateful.


Sincerely,
- Richard

 

Hi, turning the ignition On with the TPS unplugged caused the lights on your dash.
I was in Vaduz 2 days ago having my tester(Autel MD702,works on ABS,engine and gearbox) in my trunk, Zurich was on my list too...

 

Gentlemen,


As mentioned before, I had no luck with my D900 scanner, and it was in the process of using it that triggered my CEL (believed to be due to turning to ignt with the TPS and MAF unplugged).


Anyway, I borrowed a uniTEC OBD II Scanner from a work colleague today to attempt to clear the CEL in my lunch break.

I read the codes and received the following:

• P0102
• P0112
• P0122
• P0222
• C1175
• P1111 P
• C1175 P

Most of these made sense what with the TPS and MAF being unplugged, so I took note of them and hit clear...

What happened next I was not expecting. The scanner claimed the clear had been successful, so I switched the ignition off and unplugged

As per protocol, I checked the car for codes again, expecting them to be clear. However up came:

• P1642
• C1175
• P1000 P
• C1175 P

Along with these codes the car was in restricted performance mode and the climate control module was beeping with 'Err' up on the display. Turning the CC on and off fixed that however.

Thinking 'bugger', I attempted to clear the codes for a second time. Again the scanner was happy and again I checked the car subsequently.

This time these codes were read:

• P1638
• P1642
• P1000 P
• P1637 P
• P1643 P

I understand these later errors are related to CAN problems?

Now, along with the RP message I had added a GBOX FAULT message. Brilliant.

I took the car out in RP mode, I think I was also just in 3rd gear. I when up and down a quite road and then pulled over and killed the engine. After restarting I was out of RP mode and the gearbox message had also disappeared. I drove back to work and the car was working fine, albeit still with the CEL on and the ASC/TRAC messages cycling (and ABS light on naturally).


This has thrown and frustrated me. The lack of consistency in the codes I do not understand. If there is anyone out there who can decipher what this might mean, I shall be truly grateful.

Sincerely,
- Richard

 

Richard, in what shape is your battery? Meaning, not the actual shape of the battery…but rather, the voltage etc?

 

Hello,

12.64v static, 14.00v running.


Cheers,
- Richard

 

I suspect, but obviously am not sure, that your CAN bus codes are artifacts from connection of the code reader. Many of us experience that occaisonally when there are no faults, but the CEL comes on as we connect, but only the CAN bus code is reported. Ergo, the scanner is causing the code.

 

Hello,

Thank you for your reply. From trawling the internet this was on my shortlist of possible problems, although it seems like I've jumped into a paradox. How can I clear the codes if, to clear the codes, one needs to throw some codes?

Is this only a function of some scanners?

What is my best option from here? Are my final batch of codes noting to worry about (assuming I gain access to a 'better' scanner)

I have purchased (awaiting delivery) an ELM 327 WiFi, with view to connect to an iOS device. I'm having no luck with readers, so I assume this won't work either.


Thanks again,
- Richard

 

Most codes will clear the CEL after they are no longer "in alarm". The code is kept as a "stored code". Also, the codes generally throw as you connect your scanner, not after it is connected. Honestly, I have never had all 4 CAN bus faults at once, and you have symptoms consistent with CAN bus errors, with no codes other than CAN bus, so you might just have a CAN bus error. I would have a look at all of the CAN bus connectors. Have you downloaded the JTIS manuals yet so you can follow the bus throught the various modules? I seem to recall that the gearshift module can cause poblems, along with the instrument cluster. Intermittent bus problems are a bitch to troubleshoot, so I hope you luck out and find a corroded connector.

I assume you know that C1175 is the left rear wheel sensor, wiring to it, or "CM" failure, which I assume means "control module", meaning the ABS module.

 

My problem with TB showed similar codes, a short quote from my old thread " I got Gearbox fault, Low brake fluid, Engine stalled, plus the codes C1155, P1796, P1638, P1642, P0121 and P1000".

A second hand one from ebay saved me.

 

Thank you all for the advice. Yes, I had originally thought I'd be needing a replacement TB (hence the title of this thread). I still can't believe no one sells a standalone TPS? It's just a potentiometer that is bolted on, not even bonded. I want to look into a finding an TPS off another car (make and/or model) with the same properties, and retrofitting. If this is successful, it must be possible to save other XJ owners the £500 bill for a TB when all they need is a volume knob off of an old Technics receiver.


Anyway, that's an aside for now.

On my drive home today, I was tootling along quite happily, with my friendly amber light on, when up pops 'GBOX FAULT'. It seemed to lock me into 3rd. No restricted performance on the engine side, just the locked ratio. After a restart, all was well. This happened twice in my 30 minute commute home. The final time I was parking up in the garage and noticed, with the fault message up, that the car was very delayed engaging reverse.

I pulled the codes:

• P1797
• P0730 P

As well as the C1175 rear LHS speed sensor fault. I understand these latest codes are 'box related and claim 'wrong ratios' or something along those lines.

As I, like God, do not play with dice, can I assume that these gearbox codes are a result of the (possibly) iffy wheel speed sensor? Or have I become very unlucky?


This weekend I'al'be mostly testing the sensors and wiring with the MM and removing the ABS module for inspection.


Again, any advice gratefully received.


Sincerely
- Richard

 

Richard:
I did not look up the codes, and I would guess that no one changed your diff ratio while you were not looking, so YEAH, I think you are making a good diagnosis. It would seem that missing pulses could be interpreted as wrong ratio.

As to the TB pots, there are two pots on each circuit, that are apparently not linear in feedback, and one is oriented "rising" and the other is "falling" scale. It seems to be done in order to prevent just jumpering one wiper to the other. Obviously, the guys rebuilding the TB have found something, but I sure have not seen anyone spilling the beans on the internet. I suppose the reason it was done that way one the AJ27, with throttle by wire, is to improve the "control reliability" of the circuit. With one rising and one falling, there would be few circuit failures that could result in an improper demand for WOT, for example.