GM Service Manual Online
For 1990-2009 cars only
GEN F-Terminal Signal: The scan tool displays 0%-100%. The scan tool displays 0%-10% until the engine is started and the PCM receives a signal from the generator then the percentage varies up to 100%..

GEN 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

GEN L-Terminal Signal Command: The scan tool displays On/Off. The scan tool displays Off until the engine is running, then the PCM supplies a 5.0 V signal to turn ON the regulator, then On is displayed.

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.

TR Sw.: The scan tool displays Park, Reverse, Neutral, Drive 4, Drive 3, Drive 2, Drive 1. The scan tool displays the position of the transmission range switch.