Circuit/System Testing

2008 Pontiac Grand Prix BaseSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF. Disconnect the harness connector of the module that set the DTC. Verify that there is less than 1.0 ohm between the ground circuit and the negative battery terminal.
    • If greater than the specified value, test the ground circuit for an open/high resistance.
  2. Ignition ON. Test for 9.5-13.5 volts between the battery positive voltage and the ground circuits of the appropriate module.
    • If not within the specified range, test the battery positive voltage circuits for a short to ground or an open/high resistance.
  3. If all circuits test normal, replace the appropriate module.
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When to See a Mechanic

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

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