I was wondering if anyone can clue me in on what I need to know about changing out my engine computer. I was told that some numbers heve to match or something. I'd rather hear it from here. What do I need to know to change it. Thanks a lot!

 

Really depends on what you are driving...

You will need to match the PN on your PCM with the replacement. You will also need to get it programmed appropriately for your VIN and vehicle options.

As far as the swapping out part goes, it is not just a simple unplug and plug in the replacement. You may be able to get away with that procedure, but chances are you will have to have a CASE learn done so that your new PCM knows the appropriate CKP/CMP correction factor for precise timing control.

 

I can give you a summary of what I learn as I am in the process of doing this right now. The new one is on order and should be here soon. Just hoping it fixes my problems.

Update:

I installed the new computer and it still did not start. I finally found that the root of all my problems was a pin bent flat against in the inside of the crankshaft sensor. I reinstalled the old computer and it still started up.

 

I wanted to add that I had read somewhere that sometimes you can swap out computers without requiring a CASE relearn. In my situation the one I purchased on eBay hooked up and I believe did not require a CASE relearn as there was no SES light. This could be incorrect as I did not hook up a scanner but the Blazer did start with the new computer installed and no further changes.

 

Sometimes the learned CKP/CMP correction is close enough to not trigger a code. It is always best to have the procedure done though. It can affect efficiency.