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Home >> Chevrolet >> 2006 >> Cutaway 6.6 2 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 6.6L (LLY) - DTC P0401 To DTC P268A >> DTC P0652 or P0653 >> Circuit/System Testing

Circuit/System Testing

  1. Turn OFF the ignition for 30 seconds or until the ECM powers down.
  2. Disconnect the accelerator pedal position (APP) sensor.
  3. Turn ON the ignition, with engine OFF and measure the voltage from the 5-volt reference circuit of the APP sensor 2 to a good ground with a DMM.
    • If the voltage measures 4.7-5.2 volts, replace the APP sensor.
  4. With the DMM still connected to the 5-volt reference circuit, disconnect all other components connected to the 5-volt reference 2, one at a time.
    • If voltage changes when one of the above components are disconnected, replace the component. Refer to the appropriate replacement procedure.
  5. Test the 5-volt reference 2 circuits for a short to ground or a short to voltage.
    • If no problem was found in the 5-volt reference 2 circuit, replace the ECM.
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