B2797

DTC B2797

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 B2797
- Communication Malfunction No. 1

Circuit Description

Embedded in the vehicle key is a transponder chip. This transponder chip contains unique values (codes) that are read by the theft deterrent key transponder during vehicle starting. The vehicle key has two codes: The key code (immobilizer code) and the wireless code. Both of these codes need to be registered before vehicle starting will be allowed. The theft deterrent key transponder receives the two transponder chip codes through the theft deterrent key transponder amplifier, which acts as a power source and antenna, passively powering the transponder chip and receiving the transponder chip codes.

Conditions for Running the DTC

The key is inserted into the ignition cylinder.

Conditions for Setting the DTC

A communication error occurs between the theft deterrent key transponder and the theft deterrent key transponder amplifier.

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.

Diagnostic Aids

This DTC is set because of a condition which causes electrical noise to disrupt communications between the theft deterrent key transponder and the theft deterrent key transponder amplifier. Common causes are objects placed near the ignition column which emit a large amount of electrical noise. Also, the arrangement of keys when in the ignition will disrupt communication. Two or more vehicle keys in close proximity to the theft deterrent key transponder amplifier may cause an excessive amount of noise as both keys may be power up and attempt to transmit their codes. In either case, remove the object causing the noise or separate the keys prior to diagnosing the vehicle.

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

With the keys in the ignition, verify the keys are arranged in a manner that does not allow two vehicle keys to be near each other and inspect for any devices near the steering column which may introduce electrical noise into the immobilizer system.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the theft deterrent key transponder and the theft deterrent key transponder amplifier.
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 4
* Signal circuit terminal 15

• 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 4
* Signal circuit terminal 15

• 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 4 at the theft deterrent key transponder harness connector and signal circuit terminal 5 at the theft deterrent key transponder amplifier harness connector.
* Signal circuit terminal 15 at the theft deterrent key transponder harness connector and signal circuit terminal 4 at the theft deterrent key transponder amplifier harness connector.

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

5. Replace the theft deterrent key transponder amplifier.
6. Clear all DTCs and attempt to start the vehicle. The vehicle should start and DTCs B2797 should not set.

• If the vehicle does not start or the DTC is set, replace the theft deterrent key transponder.

Repair Instructions

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

* Theft Deterrent Key Transponder Amplifier Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for theft deterrent key transponder replacement, setup, and programming