Circuit/System Testing

IMPORTANT:

Perform the Repair Verification after completing the Circuit/System Testing.
Select Capture Info to store the DTC information with the scan tool.
This DTC may require reviewing the Freeze Frame/Failure Records carefully for accurate diagnosis.

Visually inspect the exhaust differential pressure system for any of the following conditions:
- Modifications
- Damaged components
- Bends or kinks
- Loose or improperly installed components-Ensure the smaller diameter pressure line is connected to the front of the DPF and to the smaller port of the differential pressure sensor.
- Improperly routed differential pressure lines-The exhaust differential pressure line should have a continuous downward gradient from the sensor.
Test for water in fuel contamination. Refer to Contaminants-in-Fuel Diagnosis .
Remove and visually inspect the flexible part of the exhaust differential pressure lines for internal restrictions.
- If a condition is found, replace the exhaust differential pressure lines.
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 of each other.
- If greater than the specified range, replace the EGR valve and gaskets.
Test the air induction system for leaks. Perform the Induction System Smoke System Test in Charge Air Cooler Diagnosis (Induction System Smoke Test) or Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test) or Charge Air Cooler Diagnosis (Full System Air Leak Test) .
- If an air leak is found, replace the EGR valve gaskets or EGR cooler gasket.
Test the charge air cooler (CAC) for leaks. Perform the Full System Air Leak Test in Charge Air Cooler Diagnosis (Induction System Smoke Test) or Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test) or Charge Air Cooler Diagnosis (Full System Air Leak Test) .
Test the fuel system for leaking, restricted or sticking fuel injectors, high fuel pressures, or high fuel injector flow rates. Refer to Fuel Injector Balance Test with Tech 2 .
Ignition OFF, disconnect the harness connector at the exhaust differential pressure sensor.
Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 ohms 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.
Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.
- If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
Verify the scan tool Particulate Filter Pressure Variance parameter is greater than 98 kPa.
- If less than the specified range, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM.
Install a 3A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the scan tool Particulate Filter Pressure Variance parameter is less than 13 kPa.
- If greater than the specified range, test the signal circuit terminal 2 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits, the exhaust system, and engine control system components test normal, test the exhaust differential pressure sensor. Refer to Component Testing .