P144F

P144F-EGR COOLER BYPASS STATUS LINE CIRCUIT HIGH





For complete wiring diagrams 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 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.

Diagnostic Test


1. P144F ACTIVE

Ignition on, engine not running.

With the scan tool, read DTC's.

Is DTC P144F active?

No

- Repair the intermittent condition.
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

Yes

- Go To 2

2. (K671) EGR COOLER BYPASS STATUS CIRCUIT OPEN





Turn the ignition off.

Disconnect the C1 ECM harness connector.

Disconnect the EGR Cooler Bypass valve harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the (K671) status circuit in the EGR Cooler Bypass Valve connector with the (K671) status circuit in the ECM harness connector.

Is the resistance less than 10 ohms?

Yes

- Go To 3

No

- Repair the open circuit or high resistance.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

3. P144F ACTIVE

Reconnect all harnesses.

Ignition on, engine not running.

With the scan tool, read DTC's.

Is P144F 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 (K671) EGR bypass status circuit to ground.

Turn the ignition on.

With the scan tool, read DTC's.

Did P144F go inactive?

Yes

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

No

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