B2799

DTC B2799

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC B2799
- Engine Immobilizer System Malfunction

Circuit Description

After the theft deterrent key transponder has received valid codes from the transponder chip in the vehicle key, it begins communicating with the engine control module (ECM) via two discrete immobilizer signal circuits. The theft deterrent key transponder send a communication ID to the ECM. If the ECM determines this ID is valid, engine starting will occur.

Conditions for Setting the DTC

* The ECM detects error in its communications with the theft deterrent transponder
* The ECM detects a circuit fault in either immobilizer signal circuit
* The communication ID stored in the ECM is different that the communication ID broadcast by the theft deterrent transponder

Action Taken When the DTC Sets

Engine starting will be disabled.

Conditions for Clearing the DTC

The DTC will clear when the conditions for setting the DTC have been corrected.

Reference Information
Schematic Reference

Immobilizer Schematics (Immobilizer Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Immobilizer Description and Operation (Immobilizer Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Re-register the ECU communication ID. Refer to Immobilizer System Component Programming (Programming and Relearning).

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the theft deterrent transponder and the X1 harness connector at the ECM.
2. Ignition ON, test for less than 1V between the following signal circuit terminals at the theft deterrent key transponder harness connector and ground:

* Signal circuit terminal 12
* Signal circuit terminal 13

• If greater than the specified range, test the signal circuit for a short to voltage.

3. Ignition ON, test for infinite resistance between the following signal circuit terminals at the theft deterrent key transponder harness connector and ground:

* Signal circuit terminal 12
* Signal circuit terminal 13

• If not the specified value, test the signal circuit for a short to ground.

4. Test for less than 1ohm between the following signal circuit terminals:

* Signal circuit terminal 12 at the theft deterrent key transponder harness connector and signal circuit terminal 10 at the ECM harness connector.
* Signal circuit terminal 13 at the theft deterrent key transponder harness connector and signal circuit terminal 11 at the ECM harness connector.

• If greater than the specified range, test the signal circuit for an open/high resistance.

5. Replace the theft deterrent key transponder.
6. Clear all DTCs and attempt to start the vehicle. The vehicle should start and DTCs B2799 should not set.

• If the vehicle does not start or the DTC is set, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for theft deterrent key transponder or ECM replacement, setup, and programming