Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC C0241: Powertrain Control Module (PCM) Indicated Request Torque MalfunctionDTC P0856: Traction Control Torque Request Circuit
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
ECM/PCM Requested Torque Signal Circuit | C0241 | P0856 | C0241 | -- |
Circuit Description
The EBCM and the powertrain control module PCM or engine control module ECM simultaneously control the traction control. The EBCM sends a Requested Torque message via pulse width modulated (PWM) signal to the PCM/ECM to deliver. Normal values are between 10 and 90 percent duty cycle. The signal should be at least 90 percent when traction control is not active and at lower values during traction control activations. The PCM/ECM supplies the pull up voltage that the EBCM switches to ground to create the signal.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The PCM/ECM diagnoses the requested torque PWM signal circuit and sends a class 2 serial data message to the EBCM indicating a fault is present. A fault exists in the circuit if the PCM/ECM detects one of the following conditions:
| • | The requested torque PWM signal is less than 5 percent duty cycle or greater than 95 percent duty cycle. |
| • | The requested torque PWM signal is not present for 10 seconds. |
Action Taken When the DTC Sets
If equipped, the following actions occur:
| • | The EBCM disables the ABS/TCS/VSES/DRP for the duration of the ignition cycle. |
| • | A malfunction DTC will set. |
| • | The ABS indicator turns ON. |
| • | The Stability Off indicator turns ON. |
| • | The antilock brake system (ABS) remains functional. |
Conditions for Clearing the DTC
| • | 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. |
Diagnostic Aids
Check both the EBCM, PCM, and ECM grounds, ensuring that each ground is clean and torqued to the proper specification.
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for Scan Tool Information
Circuit/System Verification
Engine ON, verify the scan tool Torque Request signal parameter in the PCM or ECM scan tool data list.
| ⇒ | The specified value should be less than 100 percent. |
Circuit/System Testing
- Disconnect the harness connector terminal 27 (ECM) or terminal 25 (PCM) at the EBCM.
- Ignition ON, test for 4.7 - 4.8 volts between the requested torque signal circuit Connector C2 terminal 15 (ECM) or Connector C1 terminal 15 (PCM) and ground.
- If all circuits test normal, replace the EBCM.
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the PCM/ECM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PCM/ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for EBCM, PCM, or ECM replacement, setup, or programming
