P0405

P0405-EGR POSITION SENSOR CIRCUIT LOW





For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


The EGR valve is opened by a motor located on top of the EGR valve. A motor shaft extends from the motor and contacts the dual-poppet valve to open the EGR valve. The EGR valve motor does not actually retract the EGR valve. The motor current is reduced and the spring pushed the EGR valve closed. The EGR valve motor contains three position sensors that detect the location of the EGR valve. These sensors report the position of the valve back to the ECM over the EGR position A, B, and C wires. The ECM will light the MIL lamp immediately after this diagnostic runs and fails. The ECM will turn off the MIL lamp after the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
Ignition on and battery voltage greater than 9 volts.

- Set Condition:
All three EGR valve position sensors are reading either High or Low.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. OTHER DTC'S
Ignition on, engine not running.
With the scan tool, read DTCs.
Is DTC P0652 present?

Yes


- Repair P0652 first.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go To 2



2. OPEN CIRCUIT




Turn the ignition off.
Disconnect the EGR valve motor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Ignition on, engine not running.
Measure the voltage from the EGR (F855) 5-volt supply circuit to the EGR (K916) return circuit at the EGR valve connector on the engine harness.
Is the voltage between 4.75 and 5.25 volts?

Yes


- Go To 3


No


- Go To 7



3. DTC P0405 ACTIVE
Turn the ignition off.
Reconnect the EGR valve motor harness connector.
Ignition on, engine not running.
With the scan tool, read DTCs.
Is DTC P0405 Active?

Yes


- Go To 4


No


- Repair complete. The removal and reinstallation of the connector corrected the failure.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



4. SIGNAL CIRCUIT OPEN




Turn the ignition off.
Disconnect the ECM harness connector.
Disconnect the EGR valve motor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the EGR Motor (K683) signal 1 circuit at the EGR valve harness connector and the EGR Motor (K683) signal 1 circuit at the ECM harness connector.
Measure the resistance between the EGR Motor (K685) signal 2 circuit at the EGR valve harness connector and the EGR Motor (K685) signal 2 circuit at the ECM harness connector.
Measure the resistance between the EGR Motor (K687) signal 3 circuit at the EGR valve harness connector and the EGR Motor (K687) signal 3 circuit at the ECM harness connector.
Is the resistance less than 10 ohms?

Yes


- Go To 5


No


- Repair or replace the engine harness for an open circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



5. SIGNAL CIRCUIT SHORT TO ANOTHER CIRCUIT




Measure the resistance between the EGR Motor (K683) signal 1 circuit at the ECM harness connector and all other circuits in the connector.
Measure the resistance between the EGR Motor (K685) signal 2 circuit at the ECM harness connector and all other circuits in the connector.
Measure the resistance between the EGR Motor (K687) signal 3 circuit at the ECM harness connector and all other circuits in the connector.
Is the resistance greater than 100k ohms?

Yes


- Go To 6


No


- Repair or replace the engine harness for an short circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



6. DTC P0405 ACTIVE
Turn the ignition off.
Reconnect the ECM harness connector.
Reconnect the EGR valve motor harness connector.
Ignition on, engine not running.
With the scan tool, read DTCs.
Is DTC P0405 Active?

Yes


- Replace EGR valve.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Repair complete. The removal and reinstallation of the connector corrected the failure.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



7. OPEN CIRCUIT




Turn the ignition off.
Disconnect the ECM harness connector.
Disconnect the EGR valve motor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the (F855) 5-volt supply circuit at the EGR valve harness connector and the (F855) 5-volt supply circuit at the ECM harness connector.
Measure the resistance between the (K916) sensor ground circuit at the EGR valve harness connector and the (K916) sensor ground circuit at the ECM harness connector.
Is the resistance less than 10 ohms?

Yes


- Go To 8


No


- Repair or replace the open engine harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



8. CONTROL CIRCUIT SHORT TO ANOTHER CIRCUIT




Measure the resistance between the EGR Motor (F855) 5-volt supply circuit at the ECM harness connector and all other circuits in the connector.
Measure the resistance between the EGR Motor (K916) sensor ground circuit at the ECM harness connector and all other circuits in the connector.
Is the resistance greater than 100k ohms?

Yes


- Go To 9


No


- Repair or replace the shorted engine harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



9. DTC P0405 ACTIVE
Turn the ignition off.
Reconnect the ECM harness connector.
Reconnect the EGR valve motor harness connector.
Ignition on, engine not running.
With the scan tool, read DTCs.
Is DTC P0405 Active?

Yes


- Replace ECM.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Repair complete.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test