Circuit/System Testing

2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: Because of the accessibility of the sunroof switch, perform the sunroof switch component test before beginning the Circuit/System Testing.

Power Sunroof Malfunction

  1. Ignition OFF, disconnect the harness connector at the sunroof control module.
  2. Test for less than 5.0 ohm between the ground circuit terminal 2 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 1 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 fuse and replace the sunroof control module.
  4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
  5. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 6 and ground.
  6. Ignition OFF, connect the harness connector at the sunroof control module.
  7. Disconnect the harness connector at the sunroof switch.
  8. Test for less than 5.0 ohm between the ground circuit terminal 5 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  9. IMPORTANT: 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.
  10. Ignition ON, momentarily install a 10-amp 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 test is normal, replace the sunroof control module.
  11. Momentarily install a 10-amp 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 test is normal, replace the sunroof control module.
  12. With the sunroof in the fully closed position, momentarily install a 10-amp 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 test is normal, replace the sunroof control module.
  13. Momentarily install a 10-amp 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 test is normal, replace the sunroof control module.
  14. 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 a 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 a 3A fused jumper wire between both signal circuits listed below and ground for less than 1 second. The roof should express open to the vent position.
    • Terminal 1
    • Terminal 4
    • If the roof does not express open to the vent position, 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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