Password Learn Procedure For Anti-Theft System (4.3L Engine)

Password learn procedure must be performed if Vehicle Control Module (VCM), Truck Body Controller (TBC) or passlock sensor has been replaced. A password is communicated between TBC and VCM to provide engine operation. If VCM has been replaced, the VCM must learn the password from the TBC.
Attempt to start engine. Engine will start and then stall. After engine stalls, leave ignition on for 10 minutes. After engine stalls the SECURITY indicator light will come on for 10 minutes and then go off. The SECURITY indicator light is located on center of instrument panel, just above the turn signal indicators.
NOTE: Ensure battery is fully charged before proceeding. Ensure steps are followed in correct order or procedure may need to be repeated.
After SECURITY indicator light goes off, turn ignition off for 30 seconds. Attempt to start engine and then leave ignition on. After engine has stalled, leave ignition on for 10 minutes. SECURITY indicator light will come on for 10 minutes and then go off. After SECURITY indicator light goes off, turn ignition off for 30 seconds.
Attempt to start engine and then leave ignition on. After engine has stalled, leave ignition on for 10 minutes. SECURITY indicator light will come on for 10 minutes and then go off.
Turn ignition off for 30 seconds. Turn ignition on and wait 30 seconds. Attempt to start engine. If engine starts, password learn procedure is complete. If engine does not start, ensure procedure was properly followed. If procedure was properly followed, check for DTCs. If any DTCs exist, perform test procedures for specified DTC and repair as necessary. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.