Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | 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 CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Run/Crank Relay Coil Control | B 1428 00 | 1 | 2 | -- |
1. No Start. SIR system will retain DTC B 1370 06 as current. 2. Vehicle will start and continue to run after the ignition key is removed. | ||||
Circuit/System Description
The body control module (BCM) controls the IGN MAIN PCB relay through the run/crank relay coil control circuit by applying voltage to the circuit. The IGN MAIN PCB 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 relay coil control circuit.
Action Taken When the DTC Sets
The module output driver will be shut down and not supply voltage to the run/crank relay coil control 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
Short to voltage in the run/crank relay coil control 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
Connector End View Reference
Power and Grounding Connector End Views
Electrical Information Reference
Circuit/System Testing
- Ignition OFF, disconnect the C4 harness connector at the BCM.
- Test for greater than 70 ohms of resistance between the BCM run/crank relay coil control circuit terminal 21 and ground.
- If the circuit tests normal, test or replace the BCM.
| ⇒ | If less than specified, test the control circuit for a short to ground. If the circuit tests normal, replace the underhood fuse block. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Refer to Control Module References for BCM replacement, setup, and programming
