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U011A



U011A-LOST COMMUNICATION WITH EXHAUST GAS SENSOR MODULE







For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation

The Oxygen Sensor is controlled by the Smart O2 Sensor 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 O2 Sensor Module in a calibrated amount of time.


Possible Causes:






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


1. U011A ACTIVE


1. With the scan tool, read DTCs.



Is DTC U011A Active?


Yes


- Go To 2

No


- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test



2. OTHER DTCs

NOTE: Repair any Voltage Low DTCs before proceeding with this test procedure.

NOTE: The J1939 Datalink is a BUS circuit which the ECM uses to communicate with the Turbo Actuator and Smart O2 Sensor Module. If the J1939 Datalink is shorted or one of these components is internally shorted, communication will be lost and DTCs will set against BOTH of these components.



Are there lost communication DTCs present against BOTH of the components listed in the note above?

Yes

- Go To 5

No

- Go To 3


3. CHECK THE SMART O2 SENSOR MODULE POWER AND GROUND CIRCUITS







1. Turn the ignition off.
2. Disconnect the Smart O2 Sensor Module harness connector.


NOTE: Check connectors - Clean/repair as necessary.

3. Ignition on, engine not running.
4. Measure the voltage between the (F960) Fused Ignition Switch Output circuit and the (Z902) Smart O2 Sensor Module Ground circuit at the Smart O2 Sensor Module harness connector.

Is the voltage within one Volt of battery voltage?

Yes

- Go To 4

No

- Using the wiring diagram as a guide, repair the (F960) Fused Ignition Switch Output circuit for an open or short to ground, or the (Z902) Smart O2 Sensor Module Ground circuit for an open.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. CHECK THE J1939 DATALINK FOR AN OPEN/HIGH RESISTANCE

1. Turn the ignition off.
2. Disconnect the Turbo Actuator harness connector.
3. Disconnect the ECM C2 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the resistance of the J1939 Datalink (+) circuit between the Smart O2 Module harness connector and the PCM C2 harness connector.
5. Measure the resistance of the J1939 Datalink (-) circuit between the Smart O2 Module harness connector and the PCM C2 harness connector.



Is the resistance below 5.0 Ohms for both measurements?


Yes


- Replace the Smart O2 Sensor Module in accordance with the service information.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Repair the J1939 circuit that measured above 5.0 Ohms for an open or high resistance.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. CHECK THE COMPONENTS ON THE J1939 DATALINK

NOTE: Disconnect only one component at a time during this next step. If the DTCs for the component that is STILL CONNECTED changes from active to stored, the component that was disconnected is faulty. If all of the DTCs remain active, then the disconnected component is not the problem. Reconnect each component before going on to the next one so that only one component is disconnected at a time.

1. Turn the ignition off.
2. Disconnect the Smart O2 Sensor Module harness connector. Cycle the ignition key on and off three times ending with the ignition on. Leave the ignition in the off position for 75 seconds each time.

NOTE: Monitor the status of the DTCs for the remaining connected components with the scan tool.

3. Turn the ignition off and reconnect the Turbo Actuator harness connector.
4. Disconnect the Turbo Actuator harness connector. Cycle the ignition key on and off three times ending with the ignition on. Leave the ignition in the off position for 75 seconds each time.


NOTE: Monitor the status of the DTCs for the remaining connected components with the scan tool.


Did the status of the DTCs change to stored for the component STILL CONNECTED when disconnecting any one of the components listed above?

Yes

- Replace the component that caused the DTC change from active to stored in accordance with the service information.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 6

6. J1939 DATALINK SHORTED TO GROUND







1. Turn the ignition off.
2. Disconnect the Turbo Actuator, Smart O2 Sensor Module and the ECM C2 harness connectors.
3. Measure the resistance between ground and the J1939 Datalink (+) circuit at the ECM C2 harness connector.
4. Measure the resistance between ground and the J1939 Datalink (-) circuit at the ECM C2 harness connector.

Is the resistance above 10k Ohms for both circuits?

Yes

- Go To 7

No

- Repair the J1939 circuit that measured below 10k Ohms for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

7. 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 above 10k Ohms for both circuits?

Yes

- Go To 8

No

- Repair the J1939 circuit for a short to the circuit that measured below 10k Ohms.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

8. J1939 DATALINK OPEN/HIGH RESISTANCE







1. Measure the resistance between the J1939 Datalink (+) circuit at the Smart O2 Sensor Module harness connector and the J1939 Datalink (+) circuit at the ECM C2 harness connector.
2. Measure the resistance between the J1939 Datalink (-) circuit at the Smart O2 Sensor Module harness connector and the J1939 Datalink (-) circuit at the ECM C2 harness connector.

Is the resistance below 5.0 Ohms for both measurements?

Yes

- Replace the Powertrain Control Module in accordance with the service information.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Repair the J1939 circuit for an open or high resistance.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
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