P144E

P144E-EGR COOLER BYPASS STATUS LINE CIRCUIT LOW





For a complete wiring diagram Refer to Diagrams/Electrical.

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 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:
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. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. OTHER DTC'S
Ignition on, engine not running.
With the scan tool, read DTC's.
Are there faults present for the VGT, EGR Airflow Control Valve or 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 2



2. (K671) EGR COOLER BYPASS STATUS CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Disconnect the ECM harness connector.
Disconnect the EGR Cooler Bypass valve harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the (K671) EGR Cooler Bypass Valve Status circuit at the ECM engine harness connector and ground
Is the resistance greater than 100k ohms?

Yes


- Go To 3


No


- Repair the short to ground.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



3. P144E ACTIVE
Reconnect all harnesses.
Ignition on, engine not running.
With the scan tool, read DTC's.
Is P144E active?

Yes


- Go To 4


No


- Repair complete.



4. ECM




Turn the ignition off.
Disconnect the EGR Cooler Bypass valve harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Use a jumper wire to connect the 12-volt supply to the valve to the (K671) EGR bypass status circuit.
Turn the ignition on.
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 Engine Control Module