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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Wiring Systems And Power Management - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC B1428 >> Circuit/System Testing

Circuit/System Testing

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  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.
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