GM Service Manual Online
For 1990-2009 cars only
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.

Generator L Terminal Signal Command: The scan tool displays On/Off. The scan tool displays Off until the engine is running, at which time it will display On.

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

Ignition 1 Signal: The scan tool displays system voltage received by the module.

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

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

Starter Relay Command: The scan tool displays Off/On. The scan tool displays Off until engine start has been requested, then it displays On.

TR Sw: The scan tool displays Park, Reverse, Neutral, Drive 5, Drive 4, Drive 3, Drive  and Drive 1. The scan tool displays the position of the transmission range switch.