P0856

DTC C0242 or P0856

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC C0242 00
- Engine Control Module Indicated Traction Control Malfunction

DTC P0856
- Traction Control Torque Request Circuit Malfunction

Circuit/System Description

When traction control is active, the electronic brake control module sends a serial data message to the engine control module requesting torque reduction. When certain engine control module DTCs are set, the engine control module will not be able to perform the torque reduction for traction control. A serial data message is sent to the electronic brake control module indicating that traction control is not allowed.

Conditions for Running the DTC

Engine running

Conditions for Setting the DTC

The engine control module detects a fault that prevents it from performing a traction control function and sends a serial data message to the electronic brake control module indicating that torque reduction is not allowed.

Action Taken When the DTC Sets

* The stability control indicator turns ON.

* The stability control Off indicator turns ON.

* The traction control Off indicator turns ON.

* The electronic brake control module disables the traction control and stability control for the duration of the ignition cycle.

Conditions for Clearing the DTC

* When the condition for setting the DTC is no longer present.

* The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred.

Note: During normal diagnostic and/or repair verification technicians may find that the ABS, Traction control and/or Stability control indicators may be ON with NO DTCs displayed by the electronic brake control module. Do not replace the electronic brake control module for this condition.

If the ABS, Traction control and/or Stability control indicators are ON with no DTCs set, perform the following steps:

1. Remove the key from the ignition, open and close the driver's door to turn off retained accessory power, and wait 60 seconds.

2. Ignition ON, if the ABS, Traction Control and/or Stability control indicators are still illuminated, operate the vehicle at speeds greater than 16 km/h (10 MPH) to complete the self test. The electronic brake control module should request all indicators to turn OFF.

3. If indicators remain ON with no DTCs set after the drive cycle, disconnect the battery for at least 60 seconds then reconnect the battery.

4. Operate the vehicle at speeds greater than 40 km/h (25 MPH), the electronic brake control module should request all the indicators to turn OFF.

Reference Information

Schematic Reference

Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

Description and Operation

ABS Description and Operation (Without F55) ABS Description and Operation (Without F55)ABS Description and Operation (With F55) ABS Description and Operation (With F55)

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify that no other DTCs are set except for C0242 or P0856.

• If any other DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

• If no other DTCs are set

3. Replace the K20 engine control module.

4. Verify that DTC C0242 or P0856 does not set while operating the vehicle within the Conditions for Running the DTC.

• If DTC C0242 or P0856 sets

Replace the K17 electronic brake control module.

• If DTC C0242 or P0856 does not set

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

Control Module References Control Module References for electronic brake control module or engine control module replacement, programming, and setup