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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 942 (Engine Controls And Fuel - 6.6L (LMM) - DTC P154B To DTC P2693) >> DTC P244B >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: Perform the Repair Verification after completing the Circuit/System Testing.
  1. Visually inspect the exhaust differential pressure system for any of the following conditions:
    • Modifications
    • Damaged components
    • Bends or kinks
    • Loose or improperly installed components
    • Improperly routed differential pressure lines

      The exhaust differential pressure line should have a continuous downward gradient from the sensor.

  2. Ignition ON, observe the scan tool EGR Position Sensor and Desired EGR Position parameters while commanding the EGR solenoid to 20 percent and 0 percent. The values should remain equal to or less than 3 percent.
    • If greater than the specified range, replace the EGR valve.
  3. Test the EGR valve gaskets and cooler gaskets for leaks. Apply a soap solution to the gaskets while commanding the TC Vane Pos. Ctrl. Solenoid ON, and inspect for excessive air bubbles at the EGR valve gaskets and cooler gaskets.
    • If an air leak is found, replace the EGR valve gaskets or EGR cooler gasket.
  4. Test the charge air cooler (CAC) for leaks. Refer to Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test) or Charge Air Cooler Diagnosis (Full System Air Leak Test) .
  5. Test the fuel system for leaking fuel injectors, high fuel pressures, or high fuel injector flow rates. Refer to Fuel Injector Balance Test with Tech 2 .
  6. Ignition OFF, disconnect the harness connector at the exhaust differential pressure sensor.
  7. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal 1 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  8. Disconnect the harness connector X1 at the ECM.
  9. Test for less than 5 ohms of resistance on the DPF differential pressure sensor circuits between the following terminals:
    • ECM X1 5-volt reference circuit terminal 14 to exhaust differential pressure sensor terminal 3.
    • ECM X1 signal circuit terminal 43 to exhaust differential pressure sensor terminal 2.
    • If greater than the specified range, repair the affected circuit for an open/high resistance.
  10. If all circuits and engine control components test normal, test the exhaust differential pressure sensor.
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