What do they mean?

[1980scottsdale]

What do PCM, ECM, and OBD-II stand for?

[Dubyagee]

Programmable control module, electronic control module and On board diagnostics two. If I'm not mistaken.

[1980scottsdale]

Thsnks for the info!

[orange ss]

PCM = Powertrain Control Module
ECM = Engine Control Module
OBD II = same as above

[VinceTrifecta]

An aside regarding the xCM acronyms... There's been a number of names GM has used over the years to refer to these control modules that run our EFI vehicles.

Back in the 80s, they called it "ECM", for engine control module (or possibly electronic control module).

In the 90s, when automatic transmission control became computerized, they changed the term to "PCM", for powertrain control module since the same module controlled both engine and transmission operations.

Sometime in the mid to late 90s, particularly in the truck division they started calling it a "VCM", or Vehicle Control Module.

When GM started separating the transmission control and engine control into separate modules (circa 2005 with the LS2, possibly earlier with the diesels), they went back to the term "ECM", to refer to the control module for the engine, and added a new one, "TCM" for transmission control module.

For the 2008 model year, GM will be using separate controllers for the engine and transmission on all their consumer vehicles as they roll out GMLAN (CAN based) architecture.