B2780

DTC B2780

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 B2780
- Push Switch/Key Unlock Warning Switch Malfunction

Circuit/System Description

The theft deterrent key transponder monitors the status of the ignition key alarm switch. The ignition key alarm switch is ON when the ignition switch is ON.

Conditions for Running the DTC

The key is inserted into the ignition cylinder.

Conditions for Setting the DTC

The ignition key alarm switch is not detected ON when the ignition switch is ON.

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

Observe the scan tool Key in Ignition parameter. The reading should change between Yes and No and change when the ignition key is inserted and removed from the ignition cylinder.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ignition key alarm switch.
2. Ignition OFF, test for less than 1ohm between the ground circuit terminal 1 and ground.

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

3. Ignition ON, verify the scan tool Key in Ignition parameter is No.

• If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the theft deterrent key transponder.

4. Install a 3A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 1. Verify the scan tool Key in Ignition parameter is Yes.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the theft deterrent key transponder.

5. If all circuits test normal, test or replace the ignition key alarm switch.

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 replacement, setup, and programming