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 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the GDO.
  2. Ignition OFF, test for less than 5 ohms of resistance between the ground circuit terminal 3 and ground.
    • If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify 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.
  4. IMPORTANT: This step will clear any learned transmitters from the GDO. This will require reprogramming by the customer to reestablish GDO functionality.
  5. Ignition ON, hold the two outer buttons on the GDO for 30 seconds. After 20 seconds, the LEDs will flash indicating that all learned transmitter values have been cleared. After an additional 10 seconds, the LEDs will flash again indicating it has entered the diagnostic mode. Place the J 41540Β  adjacent to the GDO and press each button of the GDO one at a time. See Special ToolsΒ . The tester should indicate when each button is pressed.
    • If the tester indicates that one or more of the buttons does not respond, replace the GDO.
  6. Instruct the customer to program the GDO. Refer to the vehicle owners manual. A possible rolling code or incompatibility with the GDO receiver will prevent programming. Refer to www.learcar2u.com or 1-866-572-2728.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.