New PCM risks?

borris · June 20, 2005

Hey there,

New to the board, so please, be nice!

I am wanting to get a programmed PCM from a guy who claims he can program new factory Chevy PCM's to whatever spec you need. Shift points, firmness, the typical stuff. Since it is a new PCM that will replace my factory one, he is saying that I will need to get a crank re-learn done on it so that the new PCM knows where my crank position is. I have spoken to a few shops, as well as aservice writer at my dealership, and every one has said to stay away from mods like this, it could kill my truck. I even explained that many people get PCM mods done all the time, no problems, but they were not buying it, especially the fact that I would have to get this "re-learn" done.

So, is the "time bomb" they are claiming, waiting to fry everything in my truck when I least expect it?

-Is this crank re-learn common? And if I have the dealership do it is my warranty out the window?

-Who else besides a GM tech can do this? I was told "Pathfinder" software is what I need to get it done.

-What ARE the potential risks of this, and, since I will still have my old PCM, could I not just plug that back in if I have any problems?

Oh, 2004 Silverado 4.8L Automatic

Thanks!

GM-Tech · June 20, 2005

Sometimes you have to do a crank relearn after programming a PCM, most times you don't. I'm talking about updating the factory calibration, I can't speak for some aftermarket thing. This takes about 2 minutes to do.

Will the dealer know you have aftermarket programming? Not unless you tell them, but you better, because you never know when you go in for something and they might update your PCM's calibration, wiping out your hundreds of dollars worth of custom programming.

Yeah, you could probably just plug in your original PCM if you have a problem.

Mark_in_Tulsa · June 20, 2005

Sometimes you have to do a crank relearn after programming a PCM, most times you don't. I'm talking about updating the factory calibration, I can't speak for some aftermarket thing. This takes about 2 minutes to do.

Will the dealer know you have aftermarket programming? Not unless you tell them, but you better, because you never know when you go in for something and they might update your PCM's calibration, wiping out your hundreds of dollars worth of custom programming.

Yeah, you could probably just plug in your original PCM if you have a problem.

<{POST_SNAPBACK}>

If you do have to go get a crank relearn, can you drive the truck to the dealer or do you have to tow it?

steve summers · June 20, 2005

Sometimes you have to do a crank relearn after programming a PCM, most times you don't. I'm talking about updating the factory calibration, I can't speak for some aftermarket thing. This takes about 2 minutes to do.

Will the dealer know you have aftermarket programming? Not unless you tell them, but you better, because you never know when you go in for something and they might update your PCM's calibration, wiping out your hundreds of dollars worth of custom programming.

Yeah, you could probably just plug in your original PCM if you have a problem.

<{POST_SNAPBACK}>

If you do have to go get a crank relearn, can you drive the truck to the dealer or do you have to tow it?

<{POST_SNAPBACK}>

I did a PCM upgrade on my '03 Silverado SS. It was from a reputable online PCM programmer and I opted to do the PCM swap. It did throw the code for the crank re-learn, the truck drove just fine, the SES light was annoying to me.

I took it to the Dealer(Riverside) and acted dumb. They called and told me the PCM had been changed and the relearn was going to cost me $180. I told them to leave it alone and I would come and get it. They called back and said they would do it for the $65 diag fee that they were going to charge me anyway. I had the truck in for warranty work many times after that and the PCM change was never an issue.

The PCM vendor covered the re-learn fee for me.

borris · June 20, 2005

Sometimes you have to do a crank relearn after programming a PCM, most times you don't. I'm talking about updating the factory calibration, I can't speak for some aftermarket thing. This takes about 2 minutes to do.

Will the dealer know you have aftermarket programming? Not unless you tell them, but you better, because you never know when you go in for something and they might update your PCM's calibration, wiping out your hundreds of dollars worth of custom programming.

Yeah, you could probably just plug in your original PCM if you have a problem.

<{POST_SNAPBACK}>

If you do have to go get a crank relearn, can you drive the truck to the dealer or do you have to tow it?

<{POST_SNAPBACK}>

I would have to tell the dealer what is going on, otherwise, they might flash it. That is why I'm concerned that they will flag me for future warranty work

Apparently it is OK to drive for a while, but he reccomends the re-learn gets done asap. So you would not have to tow it to the re-learn.