U040F

U040F-INVALID DATA RECEIVED FROM REDUCTANT CONTROL MODULE





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

Theory of Operation

The Diesel Exhaust Fluid (DEF) Dosing Control Unit is used to control the operation and monitoring of the Diesel Exhaust Fluid system. The DEF Dosing Control Unit shares information with the Powertrain Control Module (PCM) over the J1939 Data Link. The DEF Dosing Control Unit will illuminate the MIL light via the PCM immediately after the diagnostics runs and fails. The DEF Dosing Control Unit will turn off the MIL light via the PCM when the monitor runs and passes in three consecutive key cycles.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
An unexpected data link message was sent from the PCM to the DEF Dosing Control Unit and was unable to be interpreted.





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

1. OTHER DTCs
1. Ignition on, engine not running.
2. With the scan tool, View DTCs.

Is DTC U010E active?

Yes

- Perform the diagnostic procedure for U010E before continuing.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 2

2. U040F ACTIVE

Is DTC U040F active?

Yes

- Go To 3

No

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

3. CHECK THE POWERTRAIN CONTROL MODULE
1. Turn the ignition off.
2. Disconnect the DEF Dosing Control Unit harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Ignition on, engine not running.
4. With the scan tool, View DTCs.

Is the DTC U010E active?

Yes

- Replace the DEF Dosing Control Unit. Diesel Exhaust Fluid Dosing Control Unit - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Powertrain Control Module. Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.