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Home >> Chevrolet >> 2006 >> Chevy Express G2500, Van Cargo Extended, 6.6 2 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 6.6L (LLY) - DTC P0401 To DTC P268A >> DTC P0405 >> Circuit/System Testing

Circuit/System Testing

  1. With the ignition ON and the EGR valve disconnected, measure the voltage from the 5-volt reference circuit of the EGR valve to a good ground and observe that the DMM measures 4.98-5.02 volts.
    • If the voltage is less than 4.98 volts, test for an open in the 5-volt reference circuit or for a faulty ECM.
  2. With the ignition ON and the EGR valve disconnected, connect a jumper wire between the 5-volt reference circuit of the EGR valve and the signal circuit of the EGR valve and observe with a scan tool that the EGR sensor parameter displays 4.98-5.02 volts.
    • If the EGR Sensor parameter is less than 4.98 volts, test the signal circuit for an open or short to ground, high resistance, or for a faulty ECM.