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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting >> Diagnostic Information and Procedures >> Stop Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

Stop Lamp Switch Circuit Test

  1. Ignition OFF, disconnect the harness connector at the stop lamp switch.
  2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal B and ground.
    • If less than the specified range, test the ignition circuit for a short to ground or an open/high resistance.
  3. Verify the scan tool Stop Lamp Switch Status parameter is approximately 1023 counts.
    • If not the specified value, test the signal circuit terminal A for a short to voltage. If the circuit tests normal, replace the BCM.
  4. Install a 3A fused jumper wire between the signal circuit terminal A and the ignition circuit terminal B. Verify the scan tool Stop Lamp Switch Status parameter is 1 count.
    • If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the stop lamp switch.

Stop Lamp Circuit Test

  1. Ignition OFF, disconnect the X4 harnes connector at the BCM.
  2. Ignition ON, verify a test lamp illuminates between the terminals listed below and ground.
    • Terminal 1
    • Terminal 2
    • Terminal 4
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
  3. Connect the X4 harnes connector at the BCM.
  4. Ignition OFF, disconnect the harness connector at the affected stop lamp.
  5. Verify that a test lamp illuminates between the listed ground circuit terminal and ground.
    • Stop/park lamp terminal A
    • CHMSL terminal B
    • Aux stop/turn lamp terminal A
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the listed stop lamp control circuit terminal and ground circuit terminal.
    • Stop/park lamp terminal D
    • CHMSL terminal A
    • Aux stop/turn lamp terminal C
  7. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.
  8. If all circuits test normal, test or replace the affected stop lamp.
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