GM Service Manual Online
For 1990-2009 cars only
Battery Voltage: The scan tool displays Volts. The scan tool displays the battery voltage received by the module.

Crank: The scan tool displays Yes/No. The scan tool displays yes when the module receives battery positive voltage on the crank request signal circuit.

Crank Request Signal: The scan tool displays Yes/No. The scan tool displays No until the ignition is placed into the START position then Yes 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 PCM 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 PCM.

IMS: The scan tool displays Park, Park/Reverse, Reverse, Reverse/Neutral, Neutral, Neutral/Drive 4, Drive 4, Drive 4/Drive 3, Drive 3, Drive 3/Drive 2, Drive 2, Drive 2/Drive 1, Drive 1, INVALID, and OPEN. The scan tool displays the physical position of the Internal Mode Switch (IMS) of the transmission.

Starter Enable Relay Circuit Status: The scan tool displays Fault/OK/Invalid State. The scan tool displays Fault until the ignition is placed into the START position then OK is displayed.

Starter Relay Command: The scan tool displays ON/OFF. The scan tool displays Off until the ignition is placed into the START position and all parameters are met for a safe crank, then it reads On.

Volt Lamp: The scan tool displays On/Off. The scan too displays On when the module commands the volts lamp to be ON.