Hi all,

Back in March last year I got the dreaded TPS error. I took it to a couple of mechanics, and after charging me rather a lot of money, the problem was 'fixed' by wrapping a cable tie around the TPS.

Since then I had 7 months of trouble free motoring, until I took the car away over the Christmas holidays, when the issue came back... with a vengeance.
ASC Not Available, TRAC Not Available, Restricted Performance. Yay.
Now I know this has been covered several times, and I've searched the threads, but I would still like to run through some options and get people's opinions before I spend too much money chasing rabbits.

The problem only seems to appear when off-throttle, or sometimes very light throttle, ie cruising at a constant speed, or more usually, when getting off throttle to reduce speed when coming up to a small town.
This is the good news I guess, as every time it happened I was always able to safely pull over and find somewhere to stop, turn the car off, wait 5 seconds or so, then start the car and head on my way again. I would hate to think what could have happened if it did it while I had my foot down going up a hill, or overtaking, especially on New Zealand's narrow winding roads.
This isn't a constant problem either. Usually it doesn't happen until I've been driving the car for a while, perhaps 20-30 minutes. But after it does it the first time, it seems to do it a lot more often, sometimes every 5-10 minutes for the next hour or two. But then sometimes it will go for hours without a single issue. There was one point in our holiday where we had driven for about 900km over a period of days before it happened again.

Some of you may have seen the pictures of the stereo installation I had done before I went on holiday, and while this work was being done the battery went flat (for the second time in the 4 years I've owned the car). The car also came back covered in workshop dust, so I'm wondering if part of the problem could just be dirt in the throttle body assembly?
Now every time I mention this, the first thing people say is "replace the battery!", but I'm not convinced it's actually the problem. If it was, I would expect to have trouble starting the car, which I don't, and I would have thought the problem would happen more regularly, which it doesn't.
Also, I had the codes checked after it happened the first few times, and I can't remember the exact code, but the Jaguar mechanic who plugged in the diagnostic machine clearly showed me "TPS Error", and nothing else.

However, because of the stereo work I am doing, I am looking at upgrading the battery anyway. It's going to take a while to order in though, and I would really like to get the throttle body issue sorted properly, rather than waiting to see if the battery makes a difference.

So now for my options... in no particular order, based on what I've found from searching on here.

1) Test/Replace the battery2) Replace the throttle body with a used one3) Have the throttle body rebuilt, most likely through ASI4) Remove the throttle body myself and clean it myselfBonus Option 5) ASI rebuild + Maxbore

So... who's had actual experience with this issue, and with any of the solutions/companies mentioned above?
Are there any other options I've missed?

I really need to start making calls and see if I can get some confirmed prices for a used throttle body assembly, and get an exact ETA for a new battery, so hopefully I'll be able to update this soon

 

Can't really help with the main issue but $900 for a battery ? That would be £450. Top quality Bosch for an xj in the UK is about£80-90. Glad I don't live in NZ

 

Sorry, the battery I WANT is NZ$900 by the time I get it shipped and pay duty/tax

A standard battery will be a lot less, but I'm still not convinced there's anything wrong with my battery, so if I'm going to replace it then I might as well upgrade.

PS the stereo will be capable of putting out about 3500wrms once it's finished, so a bigger battery was always going to be a good idea.
Currently it's only running the front speakers though, so about 500wrms, with no sub, so the stereo isn't affecting the battery or TPS issues at the moment

 

See if this sounds familiar.

Link JagRepair.com - Jaguar Repair Information Resource

 

Thanks Gus, I did find that earlier, in fact I think it's where I found the ASI reference.

Do you know what's involved with their rebuild, and how have you found the unit? I'm guessing it solved your problem?

 

Your symptoms seem to indicate a traction control/sensor issue, not throttle body.
I would clean the wheel sensors and check the wiring for internal breaks, (common problem). It is possible to check the continuity of the wiring from the large plug near the ABS module. That plug can become corroded too.
May even be the ABS unit itself; the soldering on the relay inside tends to break after a while. Relatively easy fix, there are threads detailing the procedure.

 

Go with option 5 and get that big a** battery. You should be set then.

 

I have not heard of any problems with any of the rebuilds. On my TB I did notice me TPS cover was coming off and I sent the TB back to them and they repaired it with no questions.

However, I would make sure that your battery is in good condition. Jaguar has been known to be extremely sensitive to voltage fluctuations and has given many members a poor sense of direction. Have it tested!

 

Had a chat to my audio guy and the big battery is on it's way

Fredd60: thanks, I did see a few things about that while I was searching, but had discounted it as my problem only seems to happen at very low throttle. Luckily, from what I've seen on here, cleaning the sensors is an easy task, so it won't hurt to give them a check in the weekend anyway

 

Good move! Do you have any codes?

 

Nope, still no codes. I'm a bit hesitant to take it to the local Jag dealer and get the codes read again as they'll just be charging me money for something I know already.
For what it's worth though, when I had it checked last it hadn't throw any codes relating to low voltage, only the TPS.

The battery will probably take a few (ie 3-4) weeks to arrive, and again, I would be VERY surprised if it fixed the issue... but it was always on the to-do list, so it won't hurt to tick that off anyway

 

Was it in March when you got the TPS? What bothers me is the Restricted Performance. I can agree that the ASC & Traction Control not available being related to a low voltage issue but something triggered the Restricted Performance. When you install the battery get them to do a hard reset and clear any and all codes with an OBDII reader and see what takes place.

My Throttle Body failure did not throw codes the few times it let me down on the road not a good feeling.

 

Hmmm, now you've got me thinking... I'm sure it says "Restricted Performance" and "Engine Failsafe Mode" as well as "Trac Not Available" and "ASC Not Available". They all flash up so fast it's hard to keep track.

Yeah the first time I got the TPS error was in March. The mechanics were stumped as it wasn't throwing the codes for the TPS, so they assumed it was the battery too. Because the fault is intermittent, they had a hard time replicating it, and it wasn't until they got lucky one evening with the ODB scanner attached that it happened again and they finally saw the TPS fault code.

This time when it happened, I was on my way across the country, but was luckily passing near a Jaguar specialist (Beacham Jaguar), and I got a mechanic to quickly check the codes just to make sure I hadn't picked up any new faults. The scanner showed the TPS fault, which he then cleared, and we went on our way. There may have been another code as well, but the TPS one was all I was looking for at the time. Pretty sure there wasn't though...

As I've said though, I'm pretty sure the battery isn't the problem, I'm sure it's the throttle body. What I have no idea about though is what the specific problem is, and why it's come back

 

Attach the OBDII again and drive the car and see what takes place. Without the codes it is just a guessing game!

 

Yeah I know... I'm sure I could hear you mumbling that as I was typing it out!

It's easier said than done though, as I don't have my own scanner, and for the dealer to replicate the issue they might have to drive the car for hours/days before it happens again.
And they charge by the hour.

The plan so far is to wait until the weekend after next, then I've got a couple of mechanically minded friends who will give me a hand to take the throttle body out, check it over, clean the wheel speed sensors, check everything over, and possibly give the throttle body another quick clean.

After that I could send the throttle body away for repair/modification... or play the waiting game for the new battery, and see how it goes for a few weeks after that, then decide if I still need to get it rebuilt.

 

Had identical symptoms, a year or so after a throttle body replacement with new, usually occurring when it was humid outside - a simple cleaning of the TPS connector pins with Radio Shack contact cleaner lubricant has eliminated the issue - four+ years now with no return. Certainly try this before any expensive options.

Did you throw any codes? It wasn't until my symptoms were repeating several times an hour before mine threw a TPS voltage error code.

 

You can get a basic scanner for around $30 to $40 that will do the job. I have one I use all the time.

 

A guy that can afford a $900.00 battery even though he is pretty sure that it is not his problem can surely afford Auto Enginuity or even one of the Mongoose/Jaguar scanners. Then you can read the "hidden" diagnostics and codes and really get into your car's brain!
Good luck.

 

My car seems to have the exact same symptoms lately. Runs fine otherwise. No codes. Same error messages. I went though this about a year ago, and the problem was solved by cleaning the TB and putting cable ties around both connectors. Now the problem is back. My next move is to clean the hell out of the connectors as I really believe that is the problem, but can't think of how to fix it permanently; I only have questions: Perhaps the cable ties loosen over time? Why would I even need cable ties? Bad connector or pin design? Why would they get dirty or intermittent? Vibration? Bad TPS design? Why does it seem that everyone with an X308 has this problem at some point?
I would be interested to hear how the professional Jag mechanics solve the problem.

 

The battery is part of the audio upgrade, and should last the rest of the life of the car.
I don't intend on having any more issues with the car after this, so I don't see the point in spending $100 on a scanner that I'm only going to use once. Yeah right... It's a Jag, of course I'd end up using it again!

Luckily I have found someone who already has a scanner, so this afternoon I should be able to confirm exactly which codes it's throwing.
If I get REALLY lucky it might even go into failsafe mode while it's hooked up... but we'll just have to wait and see how that goes.

smtguy, the cable ties were put around the plugs on mine because one of the plug clips had broken off, which isn't entirely surprising for a 14 year old piece of plastic in the engine bay. I recall seeing somewhere that the TPS has a seal or gasket around it, which may deteriorate and let dirt/dust/general crap in, which could cause faults, but I believe the main issue is due to corrosion in the plug caused by using different metals on each side.

Another good clean, some dielectric grease might be all it needs...