View Full Version : question about a 79S&S

07-03-2009, 11:22 AM
I have a 79 s&s with a 351w. I have a quick question for you guys: What is box on the back of the motor marked PCM? It has a red reset button on it. Under the PCM cover there are a few wires and a couple of unidentified boxes.

07-03-2009, 11:33 AM
It is your electrical interface to the engine. Manuals for your engine for full explanation can be had here: