U011A
U011A-LOST COMMUNICATION WITH EXHAUST GAS SENSOR MODULE
Theory of Operation
The Oxygen Sensor is controlled by the Smart Oxygen Module (Smart O2 Module). This module is a smart device that receives information, such as dew point flag, engine speed, etc., via the J1939 Datalink from the Engine Control Module (ECM). It provides the ECM with the oxygen concentration signal. It also performs its own diagnostics and reports failures back to the ECM using the J1939 Datalink.
- When Monitored:
Ignition on or engine started.
- Set Condition:
The ECM does not receive a message from the Smart Oxygen Module in a calibrated amount of time.
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 DTC's.
Are there any Alternator voltage errors or low voltage errors for the Mass Airflow Sensor or EGR Airflow Control Valve?
Yes
- Repair the Alternator error or Smart Power Relay power supply.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 2
2. U011A ACTIVE
1. With the scan tool, read DTCs.
Is DTC U011A Active?
Yes
- Go To 3
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.
3. POWER SUPPLY TO SMART O2 MODULE OPEN
1. Turn the ignition off.
2. Disconnect the Smart O2 Module harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Ignition on, engine not running.
4. Measure the voltage between the Smart O2 Module power supply circuit and the Smart O2 Module ground circuit at the Smart O2 Module harness connector.
Is the voltage greater than 6.0 Volts?
Yes
- Go To 4
No
- Repair/Replace the Smart Power Relay harness for an open.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
4. J1939 DATALINK OPEN
1. Turn the ignition off.
2. Disconnect the ECM C2 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Measure the resistance between the J1939 Datalink (+) circuit at the Smart O2 Module harness connector and the J1939 Datalink (+) circuit at the ECM C2 harness connector.
4. Measure the resistance between the J1939 Datalink (-) circuit at the Smart O2 Module harness connector and the J1939 Datalink (-) circuit at the ECM C2 harness connector.
Is the resistance less than 10 Ohms?
Yes
- Go To 5
No
- Repair the open in the J1939 circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
5. J1939 DATALINK SHORTED
1. Measure the resistance between the J1939 Datalink (+) circuit at the ECM C2 harness connector and all other circuits in the ECM C2 harness connector.
2. Measure the resistance between the J1939 Datalink (-) circuit at the ECM C2 harness connector and all other circuits in the ECM C2 harness connector.
NOTE: Disregard any resistance between 50 and 70 Ohms between the J1939 (+) and the J1939 Datalink (-) pins.
Is the resistance greater than 100k Ohms?
Yes
- Go To 6
No
- Repair the short in the J1939 circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
6. J1939 DATALINK SHORTED TO GROUND
1. Measure the resistance between ground and the J1939 Datalink (+) circuit at the ECM C2 harness connector.
2. Measure the resistance between ground and the J1939 Datalink (-) circuit at the ECM C2 harness connector.
Is the resistance greater than 100k Ohms?
Yes
- Go To 7
No
- Repair the short to ground in the J1939 circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
7. SMART O2 MODULE
1. Reconnect the Smart O2 Module harness connector.
2. Reconnect the ECM C2 harness connector.
3. Ignition on, engine not running.
4. With the scan tool, read DTCs.
Is DTC U010C Active?
Yes
- Replace the Smart O2 Module.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Test Complete. The removal and installation of the connector corrected the problem.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.