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 Requested Torque MalfunctionDTC P0856: Traction Control Torque Request Circuit
Circuit Description
The electronic brake control module (EBCM) and the engine control module (ECM) simultaneously control the traction control system (TCS). The EBCM sends a Requested Torque message via a pulse width modulated (PWM) signal to the ECM. The duty cycle of the signal is used to determine how much engine torque the EBCM is requesting the ECM to deliver. Normal values are between 10 and 90 percent duty cycle. The signal should be at 90 percent when traction control is not active and at lower values during traction control activations. The ECM supplies the pull up voltage that the EBCM switches to ground to create the signal.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
C0241
The EBCM has detected an open, short to power or short to ground on the requested torque signal circuit.
P0856
One of the following conditions exists:
| • | The ECM detects that requested torque signal is out of the valid range. |
| • | The ECM 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 DTC will be current for as long as the fault is present. |
| • | When the fault is no longer present, the DTC will be a history DTC. |
| • | A history DTC will clear after 100 ignition cycles. |
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
Ignition ON, observe the scan tool Torque Request Signal parameter, the reading should be 90 percent.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the EBCM.
- Ignition ON, test for 4.7-4.8 volts between the requested torque signal circuit terminal 38 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 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 ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for ECM and EBCM replacement, setup and programming
