I just ordered a used PCM for my 01 Monte SS. The Donor car is an Impala. does the PCM definitely need to be reflashed? I made sure that all of the numbers and letters matched on both units. if it does need to be reflashed, is there anywhere i can go to get this done without going to the dealership? Also, can I take the the PCM to be reflashed alone (uninstalled) to avoid the car not starting or any other issues? Thank you in advance for all of the help!

 

First, you need to make sure the donor PCM has the same "Service Number" as you existing PCM.
Also, GM uses the same PCM in multiple cars. Example, my tuned PCM was a donor from I believe a 3400 powered Grand Am (now running a 3800 Monte). So if the drive train is NOT identical to the one your putting the PCM into, it MUST be re-programmed to match your vehicle. Did the Impala have the same engine???

Lastly, part of some of the anti-theft stuff, the PCM gets flashed with YOUR VIN #. Since the VIN from the Impala will not match the Monte, I'm not saure if a simple PCM relearn process will resolve the hurdle (my guess is, the PCM will need reprogrammed with your VIN).

Round about, I think the answer is "yes, the PCM will need reprogrammed.

Out of curiosity, why are you changing the PCM? 90% or more the problem is NOT the PCM.

 

I am changing the PCM because I am having problems with the A/C, and my cooling fans won't turn on. Also, my OBD2 reader gave 2 PCM codes. U 1000, and U1016. I have to double check, but I believe the Impala was a 3800 also. Can I bring the PCM to be programmed before I install it?

 

I have a "used" performance tuned PCM in my Monte...I know they guy that did the tune for me, required my VIN so that he could flash it to the PCM. So to to answer your questions, I believe it does need to be flashed to your car at a minimum, more may need to be done if the vehicle/ Drive-train of the other car was different. Your Vin can be programmed into the PCM off the car/ alone.

 

Both of those codes indicate a loss of communication for 2 or more seconds. Have you tried cleaning the connector and checking for a good ground at the PCM? Those would be the most common causes of those codes being set.

 

I will check that, Thanks.