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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1358 (Hybrid Controls - DTC P181C To DTC P2797) >> DTC P1A88 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: Perform Circuit/System Verification prior to performing Circuit/System Testing.
  1. Turn the ignition key to the OFF position.
  2. Disconnect the 42 volt X2 harness connector at the APM.
  3. Turn the ignition key to ON. Do not go to START.
  4. Use the scan tool APM Intermediate Voltage Control under the APM special functions list to turn on the 42 volt circuit.
    • If the APM Intermediate Voltage is not between 40 and 44 volts, replace the APM.
    • If the APM Intermediate Voltage is between 40 and 44 volts, the problem is not in the APM. This DTC can set for the following external reasons: