The power train control module, or PCM is the on-board computer in a 2001 GMC pickup. The PCM controls all the engine's systems, from transmission to emissions control. A fault with the PCM means any number of the engine's systems will not function correctly. If you have to replace the PCM this should be done by a dealership service department; they have the special equipment necessary to program the PCM. This article outlines the removal and installation of the original PCM only.
Raise the hood and locate the battery in the front driver's side of the engine compartment. Disconnect the negative (black) cable clamp from the battery terminal with an adjustable wrench.
Locate the PCM at the bottom left side of the battery. Pull the protective plastic cover off the PCM.
Detach the retaining latch from the top of the PCM then remove the PCM from the mounting bracket.
Loosen the two retaining bolts and lift the electrical connectors out of the PCM, then lift the PCM out of the engine compartment.
Installation of the PCM is the reverse of removal.
