P245C

P245C-EGR COOLER BYPASS CONTROL 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. The signal line is the command from the ECM to the bypass valve. If this line is shorted high the bypass valve be unable to bypass the cooler. EGR orifice temperatures will unexpectedly low. This is a high side driver. The ECM turns on the MIL lamp immediately after this diagnostic runs and fails. The MIL lamp is turned off once the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
Key on.

- Set Condition:
EGR Cooler Bypass signal line voltage is above a calibrated threshold.







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


Diagnostic Test


1. P245C ACTIVE
Ignition on, engine not running.
With the scan tool, read DTC's.
Is DTC P245C active?

Yes


- Go To 2


No


- Repair the intermittent condition.
- Refer to the INTERMITTENT CONDITION - DIESEL Symptom. Intermittent Condition



2. (K670) EGR COOLER BYPASS SIGNAL 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 signal circuit in the (K670) EGR Cooler Bypass Valve connector with the (K670) signal 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 - 6.7L. Powertrain Verification Test



3. P245C ACTIVE
Reconnect all harnesses.
Ignition on, engine not running.
With the scan tool, read DTC's.
Is P245C 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 (K670) EGR bypass signal circuit to ground.
Turn the ignition on.
With the scan tool, read DTC's.
Did P245C 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