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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 321 (Frame And Underbody) >> Diagnostic Information and Procedures >> DTC B051A, B051B, B051C, or B051D >> Circuit/System Testing

Circuit/System Testing

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NOTE:

If DTC B051C and/or B051D with symptom bytes 62, 63, or 2A is set, verify that the assist step motor wedge is present and the assist step motor wedge bolt is tight prior to proceeding with the following diagnostic steps. Refer to Assist Step Motor Replacement (Power BRS)  for part location and tightening specifications.

  1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
  2. Scan tool disconnected, test for less than 20 ohms between the low reference circuit terminal C and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ASC control module.
  3. Ignition ON, command the appropriate actuator with a scan tool while using the DMM Min/Max function to capture voltage. Test for greater than 9 volts between the 10-volt reference circuit terminal D and ground.
    • If less than the specified range, test the 10-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ASC control module.
  4. Command the appropriate actuator with a scan tool while using the DMM Min/Max function to capture voltage. Test for greater than 9 volts between the signal circuit terminal E and ground.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ASC control module.
  5. Connect a test lamp between the control circuit terminal A and the control circuit terminal B.
  6. Command the ASE Board to Extend and Retract with a scan tool. The test lamp should turn ON when commanding the Extend and Retract states.
    • If the test lamp remains OFF during either of the commands, test for a short to ground or an open/high resistance on either control circuit. If the circuits test normal, replace the ASC control module.
  7. If all circuits test normal, replace the ASC motor.
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