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Home >> GMC >> 2006 >> Sierra 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1645 (Engine Control System & Fuel System - 4.8L, 5.3L, 6.0L, 6.2L - DTC P0300 To DTC P1175) >> DTC P0641 or P0651 (ECM) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE: 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 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 all 5 V reference circuits. If all circuits test normal, replace the K20 ECM.
    • If greater than the specified range, test for a short to voltage on all the 5 V reference circuits. If all circuits test normal, replace the K20 ECM.
  3. Connect each component associated with the 5 V reference circuit, one at a time, while monitoring the voltage. 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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