P0403
P0403-EGR CONTROL CIRCUIT OPEN
For a complete wiring diagram, refer to the Wiring Information
Theory of Operation
Exhaust gas recirculation (EGR) is a method of reducing emissions of oxides of nitrogen. As the inert exhaust gas is recirculated, the mixture absorbs heat in the combustion chamber without interacting with the fuel/air mixture and reduces the formation of NOx emissions. After the EGR monitor conditions are met, the EGR valve is turned on and off momentarily. The EGR monitor calculated the difference in engine roughness from the EGR off condition to the EGR condition. This engine combustion stability difference as measured by engine roughness is the measure of a functional EGR system.
- When Monitored:
Engine running. Battery voltage greater than 10 Volts.
- Set Condition:
The Exhaust Gas Recirculation (EGR) Solenoid control circuit is not in the expected state when requested to operate by the Powertrain Control Module (PCM). One Trip Fault.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. DTC IS ACTIVE
1. Turn the ignition on.
2. With the scan tool, Clear DTCs in the Powertrain Control Module (PCM).
3. With the scan tool, actuate the EGR Valve Solenoid Duty Cycle to 79.9%.
4. With the scan tool, select View DTCs.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.
2. (K35) EGR CONTROL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the EGR Valve Assembly connector.
3. Disconnect the C2 PCM harness connector.
4. Turn the ignition on.
5. Measure the voltage of the (K35) EGR Control circuit in the EGR Valve Assembly harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (K35) EGR Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 3
3. (K35) EGR CONTROL CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Measure the resistance between ground and the (K35) EGR Control circuit in the EGR Valve Assembly harness connector.
Is the resistance above 100 Ohms?
Yes
- Go To 4
No
- Repair the short to ground in the (K35) EGR Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
4. (K35) EGR CONTROL CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (K35) EGR Control circuit between the EGR Valve Assembly harness connector and the appropriate terminal of C2 PCM connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 5
No
- Repair the excessive resistance in the (K35) EGR Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
5. (Z908) GROUND CIRCUIT OPEN OR HIGH RESISTANCE
1. Using a 12-volt test light connected to 12 Volts, check the (Z908) Ground circuit in the EGR Valve Assembly harness connector.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go To 6
No
- Repair the (Z908) Ground circuit for an open circuit or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
6. EGR VALVE ASSEMBLY
1. Connect the C2 Powertrain Control Module (PCM) connector.
2. Turn the ignition on.
3. With the scan tool, actuate the EGR Valve Solenoid Duty Cycle.
4. Select the Duty Cycle reading of 79.9%
5. Using a 12-volt test light connected to ground, check the (K35) EGR Control circuit in the EGR Valve Assembly harness connector.
NOTE: If the DTC is active, the actuation test may not be allowed by the PCM. If may be necessary to clear the DTCs before starting the actuation.
NOTE: The voltage supplied to the solenoid circuit during the actuation may be less than battery voltage. The test light should be illuminated, but may not be as bright as a direct connection to the battery.
NOTE: The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery.
Does the test light illuminate accordingly during the actuation?
Yes
- Verify that there is good pin to terminal contact in the Solenoid and the Powertrain Control Module connectors. Replace the EGR Valve Assembly if no problems were found with the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 7
7. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the EGR Solenoid Assembly and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Solenoid and the Powertrain Control Module connectors.
4. Refer to any Technical Service Bulletins that may apply.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module (PCM).
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.