P245A

P245A-EGR COOLER BYPASS CONTROL CIRCUIT /OPEN





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. There are two portions to this diagnostic. 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 EGR Cooler Bypass valve will send a signal between 1.0 and 1.7 volts. When this occurs the ECM logs a fault. The second portion of this diagnostic monitors Exhaust Gas Recirculation temperature. If the EGR Cooler Bypass valve was in bypass mode incorrectly, the exhaust gas recirculation temperatures would exceed a temperature limit; this condition will also trigger the fault. The ECM will light a MIL lamp immediately after this diagnostic runs and fails. The ECM will turn off the MIL lamp after the diagnostic passes in four consecutive drive cycles.

- When Monitored:
Key on

- Set Condition:
Voltage detected at status line is between 1.0 volt and 1.7 volts for more than 150 seconds consecutively.







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. OTHER DTC'S
Are there any faults present for the Exhaust Gas Recirculation Temperature sensor or EGR Aiflow Control Valve Circuit errors?

Yes


- Troubleshoot those DTC's first.


No


- Go To 3



3. P245A ACTIVE
Is P245A Active?

Yes


- Go To 4
-


No


- Repair the intermittent condition.
- Go To 7
- Refer to the INTERMITTENT CONDITION - DIESEL Symptom. Intermittent Condition



4. COOLANT SYSTEM
Check coolant system for correct coolant concentration, correct fluid level and any signs of contamination.
Does coolant system check okay?

Yes


- Go To 5


No


- Repair coolant system issue.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



5. EGR COOLER
Remove EGR cooler.
Inspect for excessive cooler fouling/debris.
Inspect aftertreatment system damage.

Is EGR Cooler Fouled, or aftertreatment system damaged?

Yes


- Clean EGR Cooler per service manual or replace if necessary or repair or replace aftertreatment system.
- Go To 7


No


- Go To 6



6. (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 harness connector with the (K671) status circuit in the ECM harness connector.
Is the resistance less than 10 ohms?

Yes


- Replace the EGR Bypass valve.
- Go To 7


No


- Repair the open circuit or high resistance.
- Go To 7



7. EXHAUST GAS RECIRCULATION (EGR) TEMPERATURE SENSOR
Remove the EGR temperature sensor and check for soot on the sensor.
Is there soot on the sensor?

Yes


- Wipe off sensor using brake cleaner or contact cleaner, allow to dry and re-install.
- Perform POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test


No


- Reinstall, repair complete.
- Perform POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test