GM Service Manual Online
For 1990-2009 cars only
Battery Voltage Signal: The scan tool displays 0-20 Volts. The scan tool displays the voltage as received by the Module or the 72-08 battery voltage message from the body control module (BCM).

GEN F-Terminal Signal: The scan tool displays 0-100%. The scan tool displays 0-10% until the engine is started and the powertrain control module engine control module (ECM) receives a signal from the generator then 5-90% 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 engine control module (ECM) supplies then the percentage value varies depending on electrical loads.

GEN L-Terminal Signal Status: The scan tool displays OK/Incomplete/Short Gnd/Open/Short B+. The scan displays the status of the Generator L terminal circuit.

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 engine start has been requested, then it reads On.

Starter Relay Circuit History: The scan tool displays Fault/OK/Invalid State. The scan tool displays Fault until the starter relay circuit history is grounded then OK is displayed.

Starter Relay Circuit Status: The scan tool displays OK/Incomplete/Short Gnd/Open/Short B+. The scan displays the status of the starter relay control circuit.

PNP Switch : The scan tool displays, In Gear/Park/Neutral/. The scan tool displays the position of the transmission range switch.