Circuit Description
When the ignition is turned ON, the key is tested by the immobilizer anti-theft system. While the key code is being read by the immobilizer control unit, the engine can start and run with any key that will turn the lock cylinder. The key code is read and compared with key codes that have been stored in the memory of the immobilizer control unit. If a valid key is detected, the immobilizer control unit sends a serial data release message to the electronic control module (ECM). Included in the release message is an identification (ID) code which assures that neither the immobilizer control unit nor the ECM has been substituted to defeat the system. If the ECM receives an invalid release message, the ECM disables the fuel injector circuit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1629 -- Theft Deterrent Start Enable Signal Not Correct
Conditions for Setting the DTC
The ECM receives an incorrect release message from the immobilizer control unit more than five times.
Conditions for Clearing the MIL/DTC
The ignition switch is turned OFF or the scan tool TROUBLE CODE CLEAR command is issued.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Theft Deterrent System Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Important: Always perform the setup procedure for the Immobilizer Module. Replace the Immobilizer Module. Refer to Theft Deterrent Module Replacement to perform the setup procedure. Did you complete the replacement? | System OK | -- |
