One of the following conditions exists
- The PCM detects that requested torque signal is out of the valid range.
- The PCM does not receive the requested torque signal.
Action Taken When the DTC Sets
When the DTC sets the TCS can not reduce engine torque, however the brake intervention portion of the TCS System remains operational.
Conditions for Clearing the DTC
- The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
- The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
- The PCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive warm-up cycles.
Diagnostic Aids
Check for poor or intermittent connections of the EBCM and the PCM. Refer to Testing for Intermittent Conditions and Poor Connections .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 4: This step tests for voltage supplied to the EBCM from the PCM.
- 5: This step tests for a shorted resistor in the PCM or a short to voltage within the requested torque signal circuit by verifying that a large voltage drop occurs when a test lamp is connected in parallel with the DMM.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: ABS Schematics | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 2 | Is DTC P0856 set? | Go to Step 3 | Go to Diagnostic Aids | |
| 3 | Use a scan tool in order to clear the DTCs. Start the engine. Does DTC P0856 set? | Go to Step 4 | Go to Diagnostic Aids | |
| 4 | Turn OFF the ignition. Disconnect from the electronic brake control module (EBCM), the harness connector containing the requested torque signal circuit. Turn ON the ignition. Use a DMM to measure the voltage between the requested torque signal circuit and a good ground. Does the voltage measure greater than the specified value? | 4.75 V | Go to Step 5 | Go to Step 6 |
| 5 | With the DMM still connected to monitor the requested torque signal circuit, connect one end of a test lamp to a good ground. Connect the other end of the test lamp to the positive lead of the DMM. Does the voltage measure less than the specified value? | 0.15 V | Go to Step 9 | Go to Step 7 |
| 6 | Test the requested torque signal circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 8 | |
| 7 | Test the requested torque signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 10 | |
| 8 | Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 10 | |
| 9 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 11 | |
| 10 | Replace the PCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 12 | ||
| 11 | Replace the EBCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 12 | ||
| 12 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does DTC P0856 reset? | Go to Step 4 | System OK | |
DTC C0241 or P0856
Circuit Description
The electronic brake control module (EBCM) and the powertrain control module (PCM) simultaneously control the traction control. The EBCM sends a serial data message to the PCM requesting torque reduction. When certain PCM DTCs are set, the PCM will not be able to perform the torque reduction for traction control. A serial data message is sent to the EBCM indicating that traction control is not allowed.
DTC Descriptor
This diagnostic procedure supports the following DTC
DTC C0242 PCM Indicated TCS Malfunction
Conditions for Running the DTC
- The ignition is ON.
- Ignition voltage is greater than 8 volts.
Conditions for Setting the DTC
The PCM diagnoses a condition preventing the engine control portion of the traction control function and sends a serial data message to the EBCM indicating that torque reduction is not allowed. The PCM will typically set a DTC and the EBCM will set this DTC.
If equipped, the following actions occur
- The EBCM disables the Traction Control System (TCS) for the duration of the ignition cycle.
- The Traction Control indicator turns ON.
- The Antilock Brake System (ABS) remains functional.
- The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
- The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
This DTC is for information only. As an aid to the technician, this DTC indicates that there are no problems in the ABS/TCS system.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: ABS Schematics | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
DTC C0242
The electronic brake control module (EBCM) and the powertrain control module (PCM) simultaneously control the Traction Control System (TCS). The PCM sends a Delivered Torque message via a pulse width modulated (PWM) signal to the EBCM. The duty cycle of the signal is used to determine how much engine torque the PCM is delivering. Normal values are between 10 and 90 percent duty cycle. The EBCM supplies the pull up voltage that the PCM switches to ground to create the signal.
DTC Descriptors
This diagnostic procedure supports the following DTCs
- DTC C0244 Pulse Width Modulated (PWM) Delivered Torque
- DTC P1689 Traction Control Delivered Torque Output Circuit
The engine is running.