Circuit Description

WARNING: This page is about a different car, the 2002 GMC Savana, 2002 Chevrolet Chevy Express, 2001 GMC Savana, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

Passlock(tm) system is provided in order to prevent vehicle theft if ignition lock cylinder is forced to rotate or ignition switch is operated while separated from ignition lock cylinder case. Passlock(tm) module provides security system sensor power and low reference for Passlock(tm) sensor. Passlock(tm) module also measures security system sensor voltage. When the correct key is used to start vehicle, a magnet on lock cylinder passes close to Passlock(tm) sensor within ignition lock cylinder case. The magnet activates the security Hall Effect sensor in Passlock(tm) sensor which completes a circuit from the security sensor signal circuit through a resistor to security sensor low reference circuit. Resistance value will vary from vehicle to vehicle. Passlock(tm) module will measure voltage on security sensor signal circuit and compare this voltage to a previously learned voltage. If voltage measured is within valid range, Passlock(tm) module will send a class 2 message to Powertrain Control Module (PCM) to enable vehicle starting. If voltage measured is not within valid range, a class 2 message will be sent to PCM to disable starting of vehicle.

If DTC B3033 sets, vehicle will not run. SECURITY indicator will be flashing. Passlock(tm) state is tamper. DTC will clear once an ignition cycle occurs without fault recurring. Theft deterrent module history codes will clear after 100 ignition cycles occur without fault recurring. A scan tool can also be used to clear DTCs.