GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2009 🢒 Yukon Denali 🢒 Engine 🢒 Engine Electrical 🢒 DTC B1428

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 Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Run/Crank Relay Coil Control

B1428 00

1

2

--

1. No Start. SIR system will retain DTC B1370 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 Run/Crank relay through the run/crank relay coil control 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 BCM detects 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

    •  Body Control System Schematics
    •  Power Distribution Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Mode Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References 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 86 and ground.
  3. Cycle the ignition ON and OFF. The test lamp should turn ON and OFF when changing ignition switch positions.
    4. ⇒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 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.
    3. ⇒If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    4. • 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.
    5. ⇒If greater than specified, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for BCM replacement, setup, and programming