U11C1
U11C1-LOST COMMUNICATION WITH DIESEL EXHAUST FLUID CONTROL UNIT
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 is the central control for the aftertreatment diesel exhaust fluid dosing system, and handles the dosing activity, tank level sensing, tank temperature sensing, line heating, and tank heating. The DEF Dosing Control Unit shares information with the Powertrain Control Module 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 and dosing of fluid into the exhaust system is disabled.
- When Monitored:
Continuously with the ignition on.
- Set Condition:
The DEF Dosing Control Unit is expecting a valid Data link message from the Powertrain Control Module, but the actual data received was unreadable or missing.
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, read DTCs.
Are there any other DEF system DTCs active?
Yes
- Repair all other DEF system DTCs before proceeding with this test procedure.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 2
2. U11C1 ACTIVE
Is DTC U11C1 active?
Yes
- Go To 3
No
- Perform the INTERMITTENT CONDITION - 6.7L diagnostic procedure. . Intermittent Condition Test
3. CHECK THE J1939 DATALINK CIRCUITS FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the DEF Dosing Control Unit C2 harness connector.
3. Disconnect the PCM C2 harness connector
NOTE: Check connectors - Clean/repair as necessary.
4. Measure the resistance of the J1939 Datalink (+) circuit between the DEF Dosing Control Unit C2 harness connector and the PCM C2 harness connector.
5. Measure the resistance of the J1939 Datalink (-) circuit between the DEF Dosing Control Unit C2 harness connector and the PCM C2 harness connector.
Is the resistance below 5.0 Ohms for both circuits?
Yes
- Go To 4
No
- Repair the J1939 circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
4. CHECK THE J1939 DATALINK CIRCUITS FOR A SHORT
1. Measure the resistance between the J1939 Datalink (+) circuit at the PCM C2 harness connector and all other circuits in the PCM C1 harness connector.
2. Measure the resistance between the J1939 Datalink (-) circuit at the PCM C2 harness connector and all other circuits in the PCM C1 harness connector.
NOTE: Disregard any resistance between 50 and 70 Ohms between the J1939 (+) and the J1939 Datalink (-) pins.
Is the resistance above 10k Ohms for both circuits?
Yes
- Go To 5
No
- Repair the J1939 circuit for a short circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
5. CHECK THE J1939 DATALINK CIRCUITS FOR A SHORT TO GROUND
1. Measure the resistance between ground and the J1939 Datalink (+) circuit at the PCM C1 harness connector.
2. Measure the resistance between ground and the J1939 Datalink (-) circuit at the PCM C1 harness connector.
Is the resistance above 10k Ohms for both circuits?
Yes
- Go To 6
No
- Repair the J1939 circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
6. DEF DOSING CONTROL UNIT
1. Turn the ignition off.
2. Reconnect the DEF Dosing Control Unit C2 harness connector.
3. Reconnect the PCM C2 harness connector.
4. Ignition on, engine not running.
5. With the scan tool, read DTCs.
Is DTC P010E 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.