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Home >> Chevrolet >> 2009 >> Traverse LS, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 3.6L - DTC P0638 To DTC P2635 >> DTC P0685, P0686, P0687, P0689, or P0690 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the powertrain relay.
  2. Ignition ON, load test for B+ between the ignition supply circuit terminal 85 and ground.
    • If less than the specified range, test the ignition supply circuit for an open/high resistance.
  3. Ignition ON, load test for B+ between the ignition supply circuit terminal 30 and ground.
    • If less than the specified range, test the ignition voltage circuit for an open/high resistance.
  4. Ignition OFF, connect a test lamp between the control circuit terminal 86 of the powertrain relay and the B+ supply circuit terminal 85, coil side of the powertrain relay.
  5. Turn ON the ignition. The test lamp should turn ON when the ignition switch is cycled ON and OFF when the ignition switch is cycled OFF.
    • If the test lamp remains ON all the time, test for a short to ground on the control circuit. If the circuit/connections test normal, replace the ECM.
    • If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.
    6. NOTE: The ignition voltage circuit is between the powertrain relay and the ECM. The ignition voltage is a feedback circuit.
  6. Connect a 15 A fused jumper wire between the B+ supply circuit terminal 30 and the ignition voltage circuit terminal 87 of the powertrain relay.
  7. Attempt to start the engine. The engine should start.
    • If the engine does not start, test the ignition voltage circuit between the powertrain relay and the ECM for a short to ground or for an open/high resistance. If the circuit/connections test normal, replace the ECM.
  8. Ignition ON, test for less than 1 V between the ignition voltage circuit terminal 87 of the powertrain relay and ground.
    • If greater than the specified value, repair the short to voltage in the ignition voltage circuit.
  9. If all circuits/connections test normal, test or replace the powertrain relay.
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