Circuit Description
When the ignition is switched on, the antenna that is integrated in the theft deterrent control module (Immobilizer) is energized. During this period the engine control module (ECM) sends a signal to the intelligent switching unit (ISU) requesting the frequency code.
The transponder key contains a security code (transponder code) that transmits via the antenna to the theft deterrent control module. The theft deterrent control module sends the code to the ISU. The ISU compares the received code with the stored transponder code. If the transponder code is recognized, the ISU blocks the speed signal input to the ECM allowing the transfer of the frequency code to the ECM. The ECM compares the received frequency code with the programmed frequency code. If the signal is recognized and matches the programmed signal the engine is allowed to start.
Conditions for Running the DTC
Vehicle battery voltage must be between 9.0-16.0 volts.
Conditions for Setting the DTC
| • | Short to ground on the theft deterrent BN/WH circuit. |
| • | Open circuit on the theft deterrent BN/WH circuit. |
| • | Open circuit on the theft deterrent YE/BK circuit. |
Action Taken When the DTC Sets
| • | The security lamp is on solid with ignition ON. |
| • | The vehicle will not start. |
Conditions for Clearing the DTC
| • | A history DTC will clear after 40 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | Use a scan tool in order to clear DTCs. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Theft Deterrent System Schematics Connector End View Reference: Theft Deterrent System Connector End Views Important: You must obtain all the keys from the vehicle owner before testing. If a component needs to be replaced, any vehicle keys not programmed during the programming procedure will be inoperative after the programming sequence is completed. Ensure that the doors, hood and trunk/rear hatch are closed prior to starting the programming procedure. If the system is placed in program mode, then the ISU will erase all previously programmed transmitters upon the receipt of the first transmitter s programming signal. Do not operate or program the transmitters in the vicinity of other vehicles that are also in the keyless entry program mode. This prevents the programming of the transmitters to the incorrect vehicle. | |||
1 | Did you perform the Theft Deterrent Diagnostic System Check? | Go to Step 2 | |
2 |
Was voltage present? | Go to Step 3 | Go to Step 4 |
3 |
Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
4 |
Did you find and correct the condition? | Go to Step 7 | Go to Step 5 |
5 | Inspect for poor connections at the harness connector of the intelligent switching unit (ISU). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
6 | Inspect for poor connections at the harness connector of the theft deterrent control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
7 |
Important: Perform the program procedure for the theft deterrent control module. Replace the theft deterrent control module. Refer to Theft Deterrent Module Replacement . Did you complete the replacement? | Go to Step 9 | -- |
8 |
Important: Perform the program procedure for the ISU. Replace the ISU. Refer to Intelligent Switching Unit Replacement in Body Control System. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
