Hello Everyone,

Sorry this is long, but I want to let you know what I have done so far. I have a 1997 XK8 (80k miles and immaculate condition) that has some trouble codes regarding the throttle body and it just starts and dies, it also has a stability control failure readout on the dash, which I read was a symptom of the throttle body issues. I think the original codes were high voltage circuits A & B. So I have been messing around with the car for a month. I started by checking and cleaning all contacts as recommended, then I purchased a used throttle body that supposedly tested good and threw it on there, and no change. I then tore both throttle bodies down I had because honestly, I didn't have much to lose. I found one of them had some serious issues with its internal bearings being almost siezed which after soaking in WD40, fixed that issue. Messed around some more, swapped around the throttle position sensors, adjusted, readjusted. Tried hard resets a dozen times which did nothing and I have a new fancy code reader and I cannot clear the codes with the new one, or my older one. The reader says codes cleared but they are still there. I then purchased a used ECM just to see if there was any change. There was! It wouldn't start at all with that one and well, probably some crazy programming needes to happen between ecu's or something. I then purchased a remanufactured throttle body for a not so cheap price. That took 3 weeks to show up and I was highly disappointed in that unit as the butterfly was hard to open and would stay stuck open when you actuated it (frozen bearings like my other one). It also was pretty dirty and looked like they just spray painted some silver over the dirt, so for $700, I got a crappy silver paint job. TPS on the unit is not new either. I went ahead and installed to see if it would idle at least. No dice and sure enough the buttefly is sticking open and I have three new trouble codes for my troubles! I am now thinking, well, buy a brand new throttle body for $1700 after tax and shipping? But am also thinking the throttle body might not be the problem. So I read the forums some more and went ahead and put in a brand new fuel pump. Still no change. Next is to test circuit resistance and possibly need to open up the harness. I am having a hard time figuring out which wires going into the ECM are the ones for the TPS etc. I purchased the Jag electronic service manual which is a big pain to scroll through. Anyways, any ideas at this point would be greatly appreciated. P.S., maybe I need to send one of those ECM's for a refurbish? Thanks.

 

You may just have an issue with the ecu, and the codes you are seeing may not really the problem. If you have a 97 xk8 with a factory untouched ecu, you essentially have a 29 year old circuit board running the show, and chances are it has some faulty capacitors. It’s not too hard to “rebuild” or “refurbish” it your self if you have some ok soldering skills. I had 13 codes on my 97 xk8 when I bought it. I read the sticky’s and info on jag repair.com and did it my self. I ordered enough capacitors to do it twice in case I messed up and it was like 35 bucks total through digikey and one from Amazon. Once completed I put the ecu back in and only had two codes, both abs module related, no need to reflash ecu, go to a dealer or anything. Worth a try and if you aren’t up to it maybe I could do it for you, or help you
along the way.

 

Thanks! I did just that, I sent the module in for refurbishment. I however did something really stupid, can't believe I did it, I am usually much more careful. I unhooked the module with the key in with the battery hooked up and the key on. I was between work meetings as was trying to multi task getting that thing shipped out. Well, now even with another engine control module I have that I plugged in, lights don't come on, a bunch of weird readings so I am thinking I fried the body control module. Basiclly nothing works except a bunch of odd different lights on the dash. No key fob, no door lights, trunk lights etc. Won't turn over now even though it used to with the other ecm I have. A code reader does not detect anything, so dead in the water. I went ahead and bought a used body control module which is on the way. I also bought somebody's used old school computer and Jag dealer interface for this series of cars. Hopefully I can sort it out one way or another once the rebuilt ECM etc. shows up and I can plug some good software into it and reset things.