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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1024 (Power Seat System) >> Diagnostic Information and Procedures >> DTC B3920 or B3921 >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF, disconnect the harness connector X1 at the MSM.
  2. Ignition ON, verify that a test does not illuminate between any of the following motor control circuits and ground:
    • Front vertical motor terminal 12
    • Front vertical motor terminal 13
    • Rear vertical motor terminal 15
    • Rear vertical motor terminal 16
    • Seat horizontal motor terminal 9
    • Seat horizontal motor terminal 10
    • If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Test for infinite resistance between the following motor control circuits and ground:
    • Front vertical motor terminal 12
    • Front vertical motor terminal 13
    • Rear vertical motor terminal 15
    • Rear vertical motor terminal 16
    • Seat horizontal motor terminal 9
    • Seat horizontal motor terminal 10
    • If less than infinite resistance, test the motor control circuit for a short to ground.
  4. Test for greater resistance values than specified between the following motor control circuits:
    • 1 ohm for front vertical motor terminal 12 and terminal 13
    • 1 ohm for rear vertical motor terminal 15 and terminal 16
    • 1 ohm for seat horizontal motor terminal 9 and terminal 10
    • If less than the specified resistance, test the control circuits for a short together or shorted motor.
  5. Ignition OFF, disconnect the harness connector X4 at the MSM.
  6. Ignition ON, verify that a test does not illuminate between any of the following motor control circuits and ground:
    • Lumbar vertical motor terminal 1
    • Lumbar vertical motor terminal 2
    • Lumbar horizontal motor terminal 12
    • Lumbar horizontal motor terminal 13
    • Seat recline motor terminal 15
    • Seat recline motor terminal 16
    • Adjustable pedal motor terminal 9
    • Adjustable pedal motor terminal 10
    • If the test lamp illuminates, test the control circuit for a short to voltage.
  7. Test for infinite resistance between the following motor control circuits and ground:
    • Lumbar vertical motor terminal 1
    • Lumbar vertical motor terminal 2
    • Lumbar horizontal motor terminal 12
    • Lumbar horizontal motor terminal 13
    • Seat recline motor terminal 15
    • Seat recline motor terminal 16
    • Adjustable pedal motor terminal 9
    • Adjustable pedal motor terminal 10
    • If less than infinite resistance, test the motor control circuit for a short to ground.
  8. Test for greater resistance values than specified between the following motor control circuits:
    • 1 ohm for lumbar horizontal motor terminal 12 and terminal 13
    • 1 ohm for recline motor terminal 15 and terminal 16
    • If less than the specified resistance, test the control circuits for a short together or shorted motor.
  9. If all circuits test normal, replace the MSM.
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