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| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
B+ | B2955 00 | B2955 00 | -- | -- |
Serial Data | B2955 00 | B2955 00 | B2955 00 | B2955 00 |
Low Reference | -- | B2955 00 | -- | -- |
When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the key is energised by the exciter coils surrounding the ignition lock cylinder. The transponder transmits a signal to the body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the engine control module (ECM). If the learned key code does not match or a transponder value is not received, the BCM will send the start disable password to the ECM.
When a keyless entry transmitter is inserted into the transmitter pocket/slot and the ignition mode switch is pressed, the transponder embedded in the transmitter is energised by the immobiliser aerial exciter coil. The transponder transmits a signal to the body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the engine control module (ECM). If the learned key code does not match or a transponder value is not received, the BCM will send the start disable password to the ECM.
Ignition is in the Accessory or Run position.
The BCM detects a circuit fault on the immobiliser aerial circuits.
| • | Vehicle starting will be disabled. |
| • | The security indicator in the instrument cluster will be illuminated. A service message will be displayed in the driver information centre. |
| • | A current DTC will be cleared when the condition for setting the DTC are no longer present. |
| • | A history DTC will be cleared after 100 malfunction-free ignition cycles or when a scan tool is used to clear DTCs. |
Immobiliser Description and Operation
Control Module References for scan tool information
If 30 Ω or greater
| 2.1. | Ignition OFF, disconnect the harness connector at the K9 BCM. |
| 2.2. | Test for less than 2 Ω in the low reference circuit end to end. |
If 2 Ω or greater, repair the open/high resistance in the circuit.
If less than 2 Ω, replace the K9 BCM.
If less than 30 Ω
If the test lamp does not illuminate
| 4.1. | Ignition OFF, disconnect the harness connector at the K9 BCM. |
| 4.2. | Test for infinite resistance between the B+ circuit and ground. |
If less than infinite resistance, repair the short to ground on the circuit.
If infinite resistance
| 4.3. | Test for less than 2 Ω in the B+ circuit end to end. |
If 2 Ω or greater, repair the open/high resistance in the circuit.
If less than 2 Ω, replace the K9 BCM.
If the test lamp illuminates
If less than 10 V
| 6.1. | Ignition OFF, disconnect the harness connector at the K9 BCM. |
| 6.2. | Test for infinite resistance between the serial data circuit and ground. |
If less than infinite resistance, repair the short to ground on the circuit.
If infinite resistance
| 6.3. | Test for less than 2 Ω in the serial data circuit end to end. |
If 2 Ω or greater, repair the open/high resistance in the circuit.
If less than 2 Ω, replace the K9 BCM.
If greater than 13 V
| 6.1. | Ignition OFF, disconnect the harness connector at the K9 BCM, ignition ON. |
| 6.2. | Test for less than 1 V between the signal circuit and ground. |
If 1 V or greater, repair the short to voltage on the circuit.
If less than 1 V, replace the K9 BCM.
If within 12-13 V
If DTC B2955 is set
Replace the K9 BCM.
If DTC B2955 is not set or is set as history
Perform the Diagnostic Repair Verification after completing the repair.
| • | Control Module References for BCM replacement, programming, and set-up |
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