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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 365 (Engine Controls And Fuel - Hybrid (LZ1) - DTC P0351 Through DTC P3449 And Troubleshooting) >> Diagnostic Information and Procedures >> DTC P0641 or P0651 (ECM) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:

    Additional DTCs may set when disconnecting components.

  1. Ignition OFF, disconnect the harness connector of all sensors for the applicable DTC. Refer to Diagnostic Aids for the appropriate sensors, above.
  2. Ignition ON, measure for 4.8-5.2 V between one of the 5-volt reference circuits and ground.
    • If less than the specified range, test for a short to ground on the 5-volt reference circuit for 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-volt reference circuit for 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-volt reference circuit, one at a time, while monitoring the appropriate scan tool 5 V Reference 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 component.
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