Circuit/System Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Power Sunroof Malfunction

  1. Ignition OFF, disconnect the harness connector at the sunroof control module.
  2. Test for less than 5.0 Ξ© between the ground circuit terminal 1 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 6 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 tests normal and the B+ circuit fuse is open, replace the sunroof control module.
  4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 3 and ground.
  5. Ignition OFF, connect the harness connector at the sunroof control module.
  6. Disconnect the harness connector at the sunroof switch.
  7. Test for less than 5.0 Ξ© between the ground circuit terminal 5 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  8. NOTE: Apply ground to the module for no longer than 2 seconds at a time or the module could be damaged.
    When performing the following tests, make sure that the sunroof or sunshade is not at its end of travel position by switching the grounded jumper to the other signal circuit if the sunroof or sunshade does not move in one direction.
  9. Ignition ON, momentarily install a 10A fused jumper wire between the signal circuit terminal 6 and ground. The sunroof should move.
    • If the sunroof does not move, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  10. Momentarily install a 10A fused jumper wire between the signal circuit terminal 4 and ground. The sunroof should move.
    • If the sunroof does not move, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  11. Crew cab only - with the sunroof in the fully closed position, momentarily install a 10A fused jumper wire between the signal circuit terminal 2 and ground. The sunroof should vent open.
    • If the sunroof does not move, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  12. Crew cab only - momentarily install a 10A fused jumper wire between the signal circuit terminal 8 and ground. The sunroof should close.
    • If the sunroof does not close, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  13. If all circuits test normal, test or replace the sunroof switch.

Power Sunroof Express Feature Malfunction

  1. Ignition OFF, disconnect the harness connector at the sunroof switch.
  2. Ignition ON, with the sunroof in the closed position, connect 3A fused jumper wires between both signal circuits listed below and ground for less than 1 second. The sunroof should express open.
    • Terminal 1
    • Terminal 6
    • If the sunroof does not express open, test the signal circuit terminal 1 for a short to voltage or an open high resistance. If the circuit tests normal, replace the sunroof control module.
  3. Ignition ON, with the sunroof in the closed position, connect 3A fused jumper wires between both signal circuits listed below and ground for less than 1 second. The sunroof should express close.
    • Terminal 1
    • Terminal 4
    • If the sunroof does not express close, test the signal circuit terminal 1 for a short to voltage or an open high resistance. If the circuit tests normal, replace the sunroof control module.
  4. If all circuits test normal, test or replace the sunroof switch.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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