P144F

P144F-EGR COOLER BYPASS STATUS LINE CIRCUIT HIGH





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

Theory of Operation

The Exhaust Gas Recirculation (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 Engine Control Module (ECM) drives the control circuit low and then high and monitors the correct status response. Throughout engine operation looks for status response voltage to be within 5-8 volts. The status line is the feedback from the EGR Cooler Bypass Valve to the ECM. There is no action taken if this fault goes active.

- When Monitored:
Key on.

- Set Condition:
Voltage on status line is detected above battery voltage.





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

1. P144F ACTIVE
1. Ignition on, engine not running.
2. With the scan tool, read DTCs.

Is DTC P144F active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION - 6.7L diagnostic procedure. Intermittent Condition Test

2. (K671) EGR COOLER BYPASS STATUS CIRCUIT OPEN




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

NOTE: Check connectors - Clean/repair as necessary.

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

Is the resistance less than 10.0 Ohms?

Yes

- Go To 3

No

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

3. ENGINE CONTROL MODULE (ECM)




1. Turn the ignition off.
2. Reconnect the C1 ECM harness connector.
3. Use a jumper wire to connect the (K671) EGR bypass status circuit to ground.
4. Turn the ignition on.
5. With the scan tool, read DTCs.

Did P144F go inactive?

Yes

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

No

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