GM Service Manual Online
For 1990-2009 cars only
Battery 1: The scan tool displays 0-20  Volts. The scan tool displays the voltage as received on the battery positive voltage circuit of the BCM.

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 OK is displayed.

GEN L-Terminal Signal Command: The scan tool displays On/Off. The scan tool displays Off until the engine is running, then the ECM 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 ECM.

Starter Relay Command: The scan tool displays On/Off. The scan tool displays Off until the ignition is placed into the START position then ON is displayed while the engine is cranking.

Starter Relay - High Volts: The scan tool displays Test Pass/Test Fail/Test Not Run. The scan tool displays the current status of the PCM CONT relay signal circuit.

Starter Relay - Low Volts: The scan tool displays Test Pass/Test Fail/Test Not Run. The scan tool displays the current status of the PCM CONT relay signal circuit.

Starter Relay - Open: The scan tool displays Test Pass/Test Fail/Test Not Run. The scan tool displays the current status of the PCM CONT relay signal circuit.