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Home >> Hummer >> 2008 >> H3 Alpha >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 5.3L - DTC P0335 To DTC P2138 >> DTC P0641 or P0651 >> Circuit/System Testing
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Circuit/System Testing

    IMPORTANT: A short to voltage on the signal circuit of certain components may cause this DTC to set.
  1. Ignition ON, disconnect the harness connector of all appropriate sensors for the applicable DTC. Refer to Diagnostic Aids .
  2. Ignition ON, measure for 4.8-5.2 volts between one of the 5-volt reference circuits and ground.
    • If less than the specified range, test for a short to ground on all 5-volt reference circuits. If all circuits test normal, replace the ECM.
    • If greater than the specified range, test for a short to voltage on all the 5-volt reference circuits. If all circuits test normal, replace the ECM.
  3. Connect each component associated with the 5-volt reference circuit, one at a time, while monitoring the voltage. Verify the voltage remains between 4.8-5.2 volts.
    • If not within the specified range when a component is connected, test the signal circuit for a short to voltage. If the circuit tests normal, replace the appropriate component.
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