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Home >> Hummer >> 2009 >> H3 Alpha >> Repair and Diagnosis >> Accessories & Equipment >> Cruise Control Systems >> Diagnostic Information and Procedures >> DTC P1574 >> Circuit/System Testing
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the stop lamp switch.
  2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal B 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, test the signal circuit terminal A for a short to ground.
  3. Verify the scan tool TCC/Cruise Brake Pedal Switch parameter displays Released.
    • If not the specified value, test the signal circuit terminal A for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Install a 3A fused jumper wire between the signal circuit terminal A and the B+ circuit terminal B. Verify the scan tool TCC/Cruise Brake Pedal Switch parameter displays Applied.
    • If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  5. If all circuits test normal, test or replace the stop lamp switch.
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