GM Service Manual Online
For 1990-2009 cars only
Crank Request Signal: The scan tool displays Yes/No. The scan tool displays Yes when the PCM receives battery positive voltage on the crank request circuit.

Generator L-Terminal Signal Command: The scan tool displays On/Off. The scan tool displays Off until the engine is running, then the PCM supplies then the percentage value varies depending on electrical loads

Ignition 1 Signal: The scan tool displays 0-20 Volts. The scan tool displays the voltage as received on the Ignition 1 circuit to the PCM.

Starter Relay Command: The scan tool displays ON/OFF. The scan tool displays Off until the ignition is placed into the CRANK position, then it reads On.