Antitheft and Alarm Systems

CIRCUIT DESCRIPTION
When the ignition is switched On, the antenna that is integrated in the Theft Deterrent Module (Immobilizer) is energized. During this period the Engine Control Module (ECM) sends a signal to terminal 2 of the Theft Deterrent Module requesting the frequency code (imo signal).

The transponder key contains a security code (transponder code) that transmits via the antenna to the Theft Deterrent Module. The Theft Deterrent Module compares the received code with the stored transponder code. If the transponder code is recognized, the Theft Deterrent Module blocks the speed signal input to the ECM allowing the transfer of the imo signal to terminal 44 of the ECM. The ECM compares the received imo signal with the programmed imo signal. If the signal is recognized and matches the programmed signal the engine is allowed to start.

Within 1.5 seconds during the transfer and the evaluation phase of the transponder code and the imo signal the engine can be started. However, if the imo signal does not match, the engine will stall immediately.

CONDITIONS FOR SETTING THE DTC
^ No transponder signal (key transmitter signal) present, transponder key defective.
^ Key used is not a transponder key.
^ Transponder key not programmed in the Theft Deterrent Module.

The above conditions must be fulfilled for at least 0.51 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The engine starts then stalls.
^ The Theft Deterrent Module stores a DTC 11 in memory.

CONDITIONS FOR CLEARING THE DTC
^ The conditions for the fault are no longer present.
^ A history DTC will clear after 20 consecutive ignition cycles if the condition for the fault is no longer present.
^ The use of a scan tool.

DIAGNOSTIC AIDS
Refer to Inducing Intermittent Fault Conditions in Diagrams.

TEST DESCRIPTION

Steps 1-11:

The following numbers refer to the step numbers on the diagnostic table:
2. This step checks which transponder key is being used.
4. This step checks the programmed status of the key being used.
10. The module may be at fault if no trouble is found with the connection at the Theft Deterrent Module.