B1428

DTC B1428

Diagnostic Instructions

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

DTC Descriptor

DTC B1428
- Ignition Switched Power Run/Crank Relay Circuit

Circuit/System Description

The body control module (BCM) controls the Run/Crank relay by applying voltage to the circuit. The Run/Crank relay is energized when the ignition switch is in RUN or START, or when a remote start is requested.

Conditions for Running the DTC

* The system voltage is between 9-16 volts.
* The DTC can only run when the output is activated.

Conditions for Setting the DTC

DTC will set when the output is activated and there is a short to ground in the circuit.

Action Taken When the DTC Sets

The module output driver will be shut down and not supply voltage to the run/crank ignition 1 voltage circuit

Conditions for Clearing the DTC

* The current DTC will clear when the module request for the output is removed or the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Circuit/System Testing

1. Ignition OFF, disconnect the Run/Crank relay.
2. Connect a test lamp between the relay control circuit and ground.
3. Cycle the ignition ON and OFF. The test lamp should turn ON and OFF when changing ignition switch positions.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the Run/Crank relay.

Component Testing

1. Ignition OFF, disconnect the Run/Crank relay.
2. Test for 70-150 ohms of resistance between terminals 85 and 86.

• If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87

4. Test for less then 2 ohms of resistance between terminals 30 and 87A.

• If greater then the specified range, replace the relay.

5. Install a 3-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Measure for less than 2 ohms of resistance between terminals 30 and 87.

• If greater than 2 ohms, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair. Verification Tests

Control Module References for control module replacement, setup, and programming Programming and Relearning