B1428
DTC B1428
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 B1428 00
- Ignition Switched Power Relay 1 Circuit
Diagnostic Fault Information
Circuit/System Description
The body control module (BCM) controls the Run/Crank relay through the run/crank ignition 1 voltage circuit by applying voltage to the circuit. The Run/Crank relay is energized when the ignition switch is in ON 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
The DTC will set only when the output is activated and there is a short to ground in the run/crank ignition 1 voltage 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.
Diagnostic Aids
* Use the DMM MIN/MAX function to capture/locate intermittent conditions.
* Short to voltage in the run/crank ignition 1 voltage circuit will cause the malfunction indicator lamp (MIL) to illuminate with the ignition key OFF, and the engine will remain running if started and the ignition key is removed.
Reference Information
Schematic Reference
* Body Control System Schematics (Electrical Diagrams)
* Power Distribution Schematics (Power Distribution Schematics)
* Power Moding Schematics (Power Moding Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Power Mode Description and Operation (Power Mode 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 Testing
1. Ignition OFF, disconnect the Run/Crank relay.
2. Connect a test lamp between the relay coil control circuit terminal 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 open/high resistance. If the circuit tests normal, replace the BCM.
4. If the test lamp illuminates 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
• If less than specified, replace the relay.
4. 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 5 ohms of resistance between terminals 30 and 87.
• If greater than specified, replace the relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
Refer to Control Module References (Programming and Relearning) for BCM replacement, setup, and programming