PCM Experts please help
Thread Starter
Teching In
Joined: Jun 2006
Posts: 10
Likes: 0
From: Phoenix, AZ
PCM Experts please help Ok my 98 TA had fuel pump failure and I take it into a great local shop. They say yep the fuel pump (original over 200K in Phoenix) BTW. New pump installed and the PCM is kicking out all kinds of 5V codes. They send out my PCM to be rebuilt as it is the rarest of three used on the 98 cars. PCM comes back and it does it again. After exhaustive diagnostics a tech says the new AC Delco fuel pump was internally shorted and this condition damaged the PCM. Another fuel pump is ordered and tested to be shorted as well. Local reps are brought into the loop and I am told they are covering it and the two pumps were made at the same time and QA should have cought it but was not done. So the PCM was sent out to be rebuilt again and came back today as unfixable. The correct PCM proved difficult to find and I am looking for options.
I believe I've told you this before. There is only 1 PCM used on 98 F-bodies. There are different calibrations that were used during the 98 model year but that has nothing to do with the PCM itself. Any of the calibrations can be flashed into the one 98 PCM used. Any of those calibrations will run your vehicle just fine as long as it is programmed for the correct rear gear ratio since the A4 cars came with two different options on that. If the shop doing your work doesn't know or understand this and thinks there are three different hardware PCMs used that is probably 99% of the problems you are having. Go find a different shop. You don't have to believe me but I've been tuning and programming these PCMs for over 10 years. I have three of them in my possession now. All the same service # and Hardware # and I can flash them with any 98 calibration I choose.
https://ls1tech.com/forums/generatio...arly-98-t.html
https://ls1tech.com/forums/generatio...arly-98-t.html
Thread Starter
Teching In
Joined: Jun 2006
Posts: 10
Likes: 0
From: Phoenix, AZ
The tech was probably referring to the multiple calibrations of 98. What I am seeking is advice on using a PCM from another year or hunting for a used 98 PCM is best. Emisions issues with a newer PCM that the car never came with when OBD II is plugged in? Of course now that AC Delco is involved I doubt they want to be part of a different PCM than 98 going in the car.
Thread Starter
Teching In
Joined: Jun 2006
Posts: 10
Likes: 0
From: Phoenix, AZ
So are there emisions issues to have a 98 car VIN and paperwork and a newer PCM. Does OBD2 show a non matching PCM and flag the car? The re-pinning sounds like a great option as long as it passes.
Peter
Peter
Only EFI Live I believe and Tunercat will let you put a 98 VIN in a 99-02 PCM. (and I'm not 100% sure EFI Live will. I don't use it but heard it will.) HP Tuners wolt do it because of the way they do licensing. The HP Tuners Beta version will allow licensing the VIN/OS Mismatch if the VIN has already been changed, but it won't do the initial change. I know Tunercat can and will do it because I use it to switch VINs all the time.
If you are not doing the re-pinning yourself I would imaging paying someone labor to do it and the tuning part would exceed the cost of another 98 PCM.
If you are not doing the re-pinning yourself I would imaging paying someone labor to do it and the tuning part would exceed the cost of another 98 PCM.
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TECH Addict
Joined: Mar 2013
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Please explain how a "shorted fuel pump" damages the PCM? Sorry but its complete BS, you better find a experienced wrench to look this over. Shorted fuel pump wouldn't and couldn't do a dam thing to the pcm. Unless the car is wired up wrong.
The PCM isn't even connected directly to the fuel pump, the pcm is connected to the fuel pump relay that turns the fuel pump on. If you shorted the fuel pump power circuit the only possible result would be a blown fuse.............................................. ................I suggest you are either being bsd or complete morons are working on your car.
2 new fuel pumps shorted??? You realize EVERY PUMP is tested before it leaves the factory with a high voltage megger?
I wouldn't put another pcm in that car until ALL the engine wiring is checked out properly.
If you need help diagnosing this I'm willing to try and walk you through it. Sorry but what they are telling you is so far out there Elvis maybe working on your car. Good Luck
The PCM isn't even connected directly to the fuel pump, the pcm is connected to the fuel pump relay that turns the fuel pump on. If you shorted the fuel pump power circuit the only possible result would be a blown fuse.............................................. ................I suggest you are either being bsd or complete morons are working on your car.
2 new fuel pumps shorted??? You realize EVERY PUMP is tested before it leaves the factory with a high voltage megger?
I wouldn't put another pcm in that car until ALL the engine wiring is checked out properly.
If you need help diagnosing this I'm willing to try and walk you through it. Sorry but what they are telling you is so far out there Elvis maybe working on your car. Good Luck
Last edited by RockinWs6; Dec 24, 2015 at 01:56 AM.
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