GM Service Manual Online
For 1990-2009 cars only
Battery Voltage: This parameter displays the voltage measured at the battery voltage circuit of the control module. Voltage is applied to the control module from the battery at all times circuit.

Crank Request Present: This parameter displays whether the ignition switch is in the crank position, requesting the control module to activate the starter relay. The scan tool displays Yes/No. The scan tool displays No until the ignition is placed into the START position then Yes is displayed.

Crank Request Signal: This parameter displays whether the ignition switch is in the crank position, requesting the control module to activate the starter relay. The scan tool displays Yes/No. The scan tool displays No until the ignition is placed into the START position then Yes is displayed.

Clutch Pedal Switch : This parameter displays the current state of the clutch pedal as determined by the control module. The scan tool displays Applied when the clutch pedal is depressed, and Released when the clutch pedal is not depressed.

GEN F-Terminal Signal Command: This parameter displays 0-100%. The display indicates the generator F terminal duty cycle in percent. The generator is capable of producing the desired voltage by adjusting the duty cycle of the field current.

GEN L-Terminal Signal: This parameter whether the control module is allowing the generator to operate. The control module can disable the generator under certain conditions. The scan tool displays Voltage / No Voltage, Voltage indicates the control module is commanding the generator on.

GEN L-Terminal Signal Command: This parameter whether the control module is allowing the generator to operate. The control module can disable the generator under certain conditions. The scan tool displays ON / OFF indicates the control module is commanding the generator on.

Ignition 1 Signal: This parameter displays the voltage measured at the ignition 1 circuit of the control module. The scan tool displays 0-20 Volts. The scan tool displays the voltage as received on the Ignition 1 circuit to the module.

PNP Switch :  This parameter indicates the range selection of the automatic transmission as received by the control module based on input from the park/neutral (PNP) switch. The scan tool displays In Gear / Park / Neutral depending on the position of the PNP switch.

Starter Relay Command: This parameter displays the control modules command state of the starter relay. The scan tool displays ON/OFF. The scan tool displays Off until the ignition is placed into the CRANK position, then it reads On. The control module will not command the relay on, if the engine is running or if there is a PNP switch or VTD concern.

Stop Lamp Pedal Switch: This parameter displays the state of the brake pedal as determined by the stop lamp pedal switch. The scan tool displays Applied / Released, Applied indicates the brake pedal is depressed.