Diagnostic Aids

WARNING: This page is about a different car, the 2004 Pontiac Sunfire and 2004 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.

The engine will not start when there is a total malfunction of the class 2 serial data circuit while the engine is not running.
The power mode master (PMM) must be able to communicate with the other modules on the class 2 serial data bus in order for the Tech 2 to communicate with the other modules.
The powertrain control module (PCM) on this vehicle has 3 junctions to the class 2 serial data bus.