P144E

P144E-EGR COOLER BYPASS STATUS LINE CIRCUIT LOW





For a complete wiring diagram refer to the Wiring Information Electrical Diagrams. Electrical Diagrams

Theory of Operation

The EGR Cooler bypass valve is used to bypass the EGR cooler when the engine is in an active regeneration mode. This is to prevent EGR cooler fouling. At key on the ECM drives the control line low and then high and monitors the correct status response. Throughout engine operation the ECM looks for status response voltage to be within 5-8 volts. This fault code will not light a MIL. The valve will continue to operate properly if it is not the cause of the fault. This fault may also be accompanied with a P245A.

- When Monitored:
Continously with key on.

- Set Condition:
The voltage detected at the ECM for the EGR Bypass Status line is below a calibratable threshold for a calibratable amount of time.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION - DIESEL (Diagnostic Procedure). Intermittent Condition Test

2. OTHER DTC'S
1. Ignition on, engine not running.
2. With the scan tool, read DTC's.

Are faults also present for the VGT and Mass Airflow sensor?

Yes

- Repair the open or short to ground in (F348) Smart Power Relay Coil Feed circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 3

3. (K671) EGR COOLER BYPASS VALVE STATUS LINE SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the ECM C1 harness connector.
3. Disconnect the EGR Cooler Bypass Valve harness connector.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the resistance between ground and the (K671) EGR Cooler Bypass Valve Status Line circuit at the ECM C1 harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short to ground in the (K671) EGR Cooler Bypass Valve Status Line circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 4

4. (K671) EGR COOLER BYPASS VALVE STATUS LINE OPEN




1. Measure the resistance of the (K671) EGR Cooler Bypass Valve Status Line circuit between the EGR Cooler Bypass Valve harness connector and the ECM C1 harness connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 5

No

- Repair the open or high resistance in the (K671) EGR Cooler Bypass Valve Status Line circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

5. ECM




1. Use a jumper wire to connect a 12-volt supply to the (K671) EGR Cooler Bypass Valve Status Line circuit.
2. Turn the ignition on.
3. With the scan tool, read DTC's.

Did P144E go inactive?

Yes

- Replace the EGR Bypass Valve.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Replace ECM.
- Replace and program the Engine Control Module. Programming and Relearning