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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 508 (Engine Controls/Fuel - 5.3L, 6.0L, 6.2L - DTC P0420 To DTC P3449 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0641 or P0651 (ECM) >> Circuit/System Testing

Circuit/System Testing

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    NOTE:

    Additional DTCs may set when disconnecting components.

  1. Ignition OFF, disconnect the harness connector of all appropriate sensors for the applicable DTC. Refer to Diagnostic Aids for the appropriate sensors.
  2. Ignition ON, measure for 4.8-5.2 V between one of the 5 V reference circuits and ground.
    • If less than the specified range, test for a short to ground on the 5 V reference circuit of each affected component. If all circuits test normal, replace the K20 ECM.
    • If greater than the specified range, test for a short to voltage on the 5 V reference circuit of each affected component. If all circuits test normal, replace the K20 ECM.
    3. NOTE:

    A short to voltage on the signal circuit of certain components may cause this DTC to set.

  3. Connect each component associated with the 5 V reference circuit, one at a time, while monitoring the appropriate scan tool 5 V Reference 1 or 2 Voltage parameter. Verify the voltage remains between 4.8-5.2 V.
    • 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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