1253C5

Question, What would cause a TAC module and a PCM module to go bad at the same time?
Would disconnecting battery cause this?

Special K

Disconnecting the battery won't due it. Maybe battery acid leaking from the battery. How do you know they both went bad?

Bob

1253C5

Wondered about the disconnecting battery - because when disconnecting the hot I got a little spark when pulling it away from the post.
I trouble shot the TAC module with a hard 1518 Code, I continued to have issues once TAC was replaced. I had it towed to the shop where the GM service person determined that the PCM was bad as well. I had them re-install the original TAC and it was bad.
Strange--- No leaking battery, never had that issue.

Special K

You should always disconnect the ground cable first. The arcing you experienced could have literally blown (exploded) the battery if a lot of gasses were present. Very dangerous.

Other than that I don't think it would have caused your problem because you didn't create any extra voltage to these modules. I would think GM could have given you an explanation.

Bob

Bill Curlee

What were the indications that made them think the PCM was BAD??

What is the ststus of the car now?? What year is the car??

Bill

1253C5

1998 C5 Bill - The car is repaire and ready for me to pick up. I requested the parts and they indicated that the parts had a CORE charge that I would have to pay for if I wanted them.
I do not have full information on what made them think PCM as well. But I will get that tomorrow when I pick up the car and let you know.

Bill Curlee

I have NEVER herd that the PCM and TAC had a CORE Charge!!!

I think someone is yanking your chain!!! I can pick up a TAC module for $207 and no core!!!!!!!!!! I got the word the other day that Fred Beans Chevy is selling then for $196 and they dont charge a core! I would go to the parts counter and ask to see the core charge in person. Then I would call another Chevy dealer and see if they say the same thing.
I have never had a PCM changed out so I can not vouge for that one but a TAC,,, I'm all over that one! Ask to get that CORE charge in writing!!!!!!!!!!!!!!!! If you figure out that there , you can ram it right back up their A$$.

Please let me know how you make out.

If your under some kind of warranty, then they need to keep the parts. If your not, they should make the parts available to you.

Bill

1253C5

OK, Here's the deal on the cored charge. I took your advice Bill before heading to pick up the car I call several Chevy Dealers including Fichtners.
They all indicated that the PCM did have a 200.00 Core charge but the TAC module didn't.
With this information I went to pick up the car. I spoke to the service rep who I had been dealing with standing firm with the information I had obtained. She contacted the parts manager who indicated there wasn't a core charge on the TAC, but they needed the part back for the warranty clam, (woops no warranty on this car any longer).
So I walked out with the TAC module but decided to pas on the PCM.
They didn’t charge me for any additional labor, just the part. They also took 50.00 off the part.
Any way I got the car it runs great, seems to have a bit more punch than before??? Strange, maybe I'm just glad to be in the chariot again.

Bill Curlee

GOOD FOR YOU!!! I'm glad your back on the road and glad that you straightened them out! I too learned something! Thanks for sharing that with us! I'm glad they gave you a brake on the labor.

Bill

LoneStarFRC

Many many dealers WILL bend you over with stuff just like this unless you come prepared. BTW, many of them also regularly lie to GM regarding "warranty" repairs done and "parts" replaced.

Save the wave

1253C5

Many many dealers WILL bend you over with stuff just like this unless you come prepared. BTW, many of them also regularly lie to GM regarding "warranty" repairs done and "parts" replaced.

I hate taking the car in for service like this - You just never know.
I did look at the PCM they pulled from my car. It looked like battery Corrosion around the cover plate screws on the PCM.
Don't know but I do know the battery has never leaked.

DidntSettle

I replaced our TAC modlue yesterday. I noticed a lot of water that had gotten behind the panel in the fender well. The bottom of the PCM was wet and dirty and the way it is set up, there are many exposed wires going to the PCM. This looks like possibly the stupidest place to locate electronic boxes that are controlling everything your car does. The connections to the TAC module looked dry and clean, but I sure didn't like the rest of the water and grime. I cleaned up everything as best I could and when I reinstalled the panel on the fender well, I sealed it with clear RTV in an attempt to keep as much water out as possible.

AWW2BAD

Most of the G.M. PCM/BCM/BRAKE MOD have core charges. They are rebuilt by General Motors unless they are only offered as New. The only reason I know this is because I have been selling G.M. parts for 15 years. Tac module does not have a core since it is offered as brand new only.