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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 18 (Lighting System) >> Diagnostic Information and Procedures >> DTC B3600 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X3 harness connector at the BCM.
  2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open high/resistance.
  3. Ignition OFF, connect the X3 harness connector at the BCM and disconnect the harness connector at the headlamp switch.
  4. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 15 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM.
  5. Verify the scan tool Dimming Control Signal parameter is less than 0.2 volts.
    • If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM
  6. Install a 3A fused jumper wire between the signal circuit terminal 13 and the B+ circuit terminal 15. Verify the scan tool Dimming Control Signal parameter is greater than 2.75 volts.
    • If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. Ignition OFF, disconnect the harness connector at the stop lamp switch.
  8. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  9. Install a 3A fused jumper wire between the signal circuit terminal D and the B+ circuit terminal C. Verify the scan tool Stop Lamp Switch Status parameter is 1023 Counts.
    • If less than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
  10. If all circuits test normal, replace the headlamp switch.
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