Q&A

The Theft Deterrent System, called a Passlock System, is designed to prevent vehicle theft by disabling the engine unless the Passlock cylinder is correctly engaged by a mechanical key. The passlock System utilizes four components for theft detection, the lock cylinder, ignition switch, electronic instrument panel cluster (IPC), and the Powertrain Control Module (PCM).

When starting the engine, the PCM looks for a password from the Instrument Panel Cluster (IPC) through the UART serial data circuit. If the password is not recognized or not present, the PCM will disable the engine. There are two modes of tamper detection:

• Short Tamper Mode - Engine may start and stall quickly. The Theft System telltale will flash on the IPC for 4 seconds.

• Long Tamper Mode (more than three starting attempts or an invalid password is received) - the engine is disabled for at least 10 minutes and the Theft System telltale will flash on the IPC for the 10 minutes.

If the engine is running and serial data communication is lost the engine will continue to run until the ignition is cycled. If serial data communication is not established while attempting to start, the engine will only start and stall. Once the vehicle has established Serial Data communication, the PCM will allow normal engine operation.

The Password learn procedure is as follows:

Attempt to start vehicle, then leave the ignition On. The Theft System telltale will flash for 10 minutes.
When the Theft System telltale stops flashing, start the vehicle. Once the vehicle is running, the password is learned. Hope this helps

try replaceing your starter

1995 Chevy Lumina . I cleaned the battery posts and now it won't turn over. The security lighjt flashes and did not before.