Description & Operation

WARNING: This page is about a different car, the 1998 Pontiac Grand Am, 1998 Oldsmobile Achieva, and 1998 Buick Skylark. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Deactivate air bag system before performing any service operation. See AIR BAG RESTRAINT SYSTEM article. DO NOT apply electrical power to any component on steering column without first deactivating air bag system. Air bag may deploy.

The PASSLOCK(R) system is designed to prevent vehicle theft by disabling the engine, unless a mechanical key is used to correctly engage the PASSLOCK(R) lock cylinder. System components include ignition switch, PASSLOCK(R) lock cylinder, Powertrain Control Module(PCM) and Instrument Panel Cluster (IPC). System logic is in IPC.

When mechanical key turns the PASSLOCK(R) lock cylinder, a Resistance Code (R-Code), is created by a rotating magnet turning past a stationary hall effect sensor. This signal (R-Code) is sent to the Instrument Panel Cluster (IPC). The IPC determines the validity of the R-Code within a preset time window, then sends a coded password to the Power Control Module (PCM), which then allows the fuel injectors to operate normally.

If R-Code is not read within the preset time window, the Vehicle Theft Deterrent (VTD) system will go into SHORT TAMPER MODE. During this short tamper mode, the vehicle will not operate for 4 seconds and theft warning light will flash. After 3 consecutive failed time window readings, or if wrong R-Code is read, the VTD will go into LONG TAMPER MODE. During the long tamper mode, the fuel injectors will be shut off for 10 minutes and theft deterrent warning light will flash. Vehicle may crank and temporarily start during tamper modes, but will soon stall due to fuel shut-off.