GM Service Manual Online
For 1990-2009 cars only
Battery:: The scan tool displays the commanded state of the charge indicator on the instrument panel cluster (IPC).

Battery Voltage (Signal):: The scan tool displays the voltage on the module's B+ circuit.

Crank Request SIgnal:: The scan tool displays Yes when the PCM receives a crank request signal.

GEN F-Terminal Signal: The scan tool displays 0%-100%. The scan tool displays 0%-5% until the engine is running, then the percentage value varies depending on electrical loads.

GEN L-Terminal Signal Command (GBCM):: The scan tool displays a percentage of duty cycle that the GBCM is supplying to the generaot L-terminal.

GEN L-Terminal Signal Command (PCM): The scan tool displays On/Off. The scan tool displays On when the GBCM is commanding the generator to charge the battery, and Off when charging is not required.

GM Part Number:: The scan tool displays the part number of the GBCM.

Ignition (1) (Signal/Voltage): The scan tool displays the voltage on the module's Ignition 1 circuit.

PNP Switch:: The scan tool displays Park/Neutral when the transmission is in park or neutral, in order to enable engine cranking.

Regulated Voltage Control Current Sensor:: The scan tool displays the current measured by the RVC current sensor, in amps.

Running State of Charge:: The scan tool displays the battery state of charge as a percentage, as calculated by the GBCM.

Start Disabled:: The scan tool displays Active when the TDM is requesting that engine cranking be disabled. This indicates a problem with the theft deterrent system, rather than a problem with the engine starting system.

TR Sw.:: The scan tool displays the selected range of the transmission.

VTD Fuel Disable:: The scan tool displays Active when the TDM is requesting that the fuel system be disabled. The PCM might also inhibit engine cranking if vehicle theft deterrent (VTD) Fuel DIsable is Active.