GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2007 🢒 VUE - AWD 🢒 DTC 🢒 DTC C0241 or P0856

Circuit Description

The controller area network (CAN) serial data circuit is a high speed serial data bus used to communicate information between the engine control module (ECM) and the electronic brake control module (EBCM). Traction control is simultaneously controlled by the ECM and the EBCM. The ECM sends engine torque data via serial data communications to the EBCM. The EBCM uses this message to determine traction control operation.

The CAN bus circuit is monitored continuously after the ignition switch is turned to the ON position.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0241 Powertrain Control Module (PCM) Indicated Requested Torque Malfunction

DTC P0856 Traction Control Torque Request Citcuit

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC
    • The EBCM receives an incorrect engine torque message 3 seconds after start-up from the ECM.
    • The EBCM continuously monitors for invalid data.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The traction control system (TCS) light emitting diode (LED) is turned OFF.
    • The EBCM will disable the TCS.
    • The antilock brake system (ABS) telltale is not illuminated.
    • The ABS is not disabled.

Conditions for Clearing the DTC
    • The condition for the DTC is no longer present.
    • Using a scan tool, clear the DTC function.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

Possible causes of this DTC are as follows:

    • Check the ECM DTCs.
    • Check the EBCM for any communication DTCs, and diagnose any powertrain or communication DTCs first.
    • The EBCM is not receiving the message from the ECM.
    • The CAN HI and CAN LO circuits are shorted together.
    • The CAN HI and CAN LO circuit is shorted to ground.
    • The CAN HI and CAN LO circuit is shorted to voltage.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for a short to ground between the CAN HI and CAN LO circuits.

    2.

  2. This step tests the CAN HI and CAN LO circuits for a short together.

    3.

  3. This step checks to see if the DTC will reset as current.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (EBCM).
  3. Disconnect the engine control module (ECM) connector.
  4. Using the digital multimeter (DMM), test the controller area network (CAN) HI and controller area network (CAN) LO circuits for a short to ground between the engine control module (ECM) and the electronic brake control module (EBCM). Refer to Testing for Short to Ground .

Did you find and correct the condition?

Go to Step 6

Go to Step 3

3

Using the DMM, test the CAN HI and CAN LO circuits between the ECM and the EBCM for being shorted together or shorted to voltage. Refer to Testing for a Short to Voltage .

Did you find and correct the condition?

Go to Step 6

Go to Step 4

4

  1. Use the scan tool in order to clear the DTCs.
  2. Test drive the vehicle. Refer to Diagnostic Test Drive .

Did DTC C0241 reset?

Go to Step 5

Go to Step 6

5

Replace the EBCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 6

--

6
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK