For 1990-2009 cars

### 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.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 033 Immobilizer Antenna Incorrect Value

### Conditions for Running the DTC

Vehicle battery voltage must be between 9-16 volts.

### Conditions for Setting the DTC

Internal defect in the theft deterrent control module

### 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
--- | --- | --- | ---
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.

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | 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 4 | --
3 | Important: Perform the program procedure for the intelligent switching unit (ISU). Replace the ISU. Did you complete the replacement? | Go to Step 4 | --
4 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 3

System OK