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2002 GMC PCM

emily triplett

By emily triplett
in Ask A GM Technician

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emily triplett New Member

emily triplett

Posted
Posted

I replaced my PCM on my 2002 GMC Sierra 5.3 with one out of a 2001 GMC with same size engine. I checked the service number on both and they matched up. I did the  passlock relearn and my truck still won't start. Am I missing something to this whole procedure?

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

I would suggest you not try to fix something by throwing money at it.  The PCM is rarely the problem.  When you turn the key on, but not try to start it, do you hear a noise from just behind you but under the rear seat area?  If no noise your next step is to go under the hood and find Schrader valve at the rear of the fuel line.  Remove the cap and press the little stem inside it.  Be careful, it may squirt at face.  If no squirt, and no noise when you first turn the key on, you will need to check all the fuses in all the fuse panels.  GM for some reason thought there was a limit to how many fuses can be in a fuse panel.  There is no such limit.  If all fuses check out good, I think there is also a relay involved in this scenario.  Good part is, every relay in the fuse panel can be used in every slot.  In other words you can just pick a starting point and remove that relay.  Go to the other end of the relays and pull that one out.  Put the one that your first removed into the spot you just removed, wash rinse repeat until you have tried them all.  At this point if you still are not hearing the fuel pump, you will need to find the wires going into the fuel pump that is located inside your fuel tank to make sure it is getting power.  If it is getting power, and you are not able to hear it, it will be a dead pump.  Go get a new pump and fuel filter.  Be real sure you change the filter as well.  That will give you something to do for a bit.  Let us know how you are making out.

carkhz316 Enthusiast

carkhz316

Posted
Posted

When you state that it won't start, can you elaborate? Does it do nothing when you turn the key,  or crank but not fire, or starts and stalls after ~2 seconds?

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