Circuit Description
The traction control system uses the antilock brake system in conjunction with the PCM fuel and ignition controls to limit drive wheel slippage during acceleration. The PCM controlled portion of the traction control system reduces engine torque by any or all of the following methods:
| • | Retarding spark timing |
| • | Altering air/fuel ratio |
| • | Altering boost PWM (VIN 1) |
| • | Shutting OFF up to three injectors |
To determine the amount of torque reduction required, the PCM monitors the TCS desired torque PWM signal from the Electronic Brake and traction control module (EBCM). The PCM also provides a TCS delivered torque PWM informing the Electronic Brake and traction control module (EBCM) how much torque is being produced by the engine. The desired torque display on the scan tool indicates the amount of engine torque requested by the EBCM. With traction control not active, desired torque should vary between 99 percent and 100 percent . The desired torque display on the scan tool is not the PWM duty cycle.
Conditions for Running the DTC
Traction control is active.
Conditions for Setting the DTC
| • | Desired torque signal PWM duty cycle is less than 5 percent or more than 95 percent . |
| • | The conditions exists for up to 10 seconds. |
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation or a broken wire inside the insulation. Check for the following conditions:
| • | Poor connection or damaged harness. |
| Inspect PCM harness for an open or short to ground in the desired torque PWM circuit, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness. |
| • | Intermittent test. |
| Using a scan tool, observe desired torque display while moving related connectors and wiring harness. If the failure is induced, the displayed value will change. This may help to isolate the location of the malfunction. |
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Is (traction control) desired torque at or near the specified value? | 100% | ||
3 |
Does voltage measure the specified value? | 5V | ||
4 |
Is frequency between the specified values? | 120 -135 Hz | ||
5 |
Is duty cycle between the specified values? | 5-95% | ||
6 |
Was a problem found? | -- | ||
7 |
Was a problem found? | -- | ||
8 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement in ABS . Is action complete? | -- | -- | |
9 | Check for a poor connection at the PCM. If a problem is found, repair as necessary. Refer to Testing for Continuity , Testing for Intermittent Conditions and Poor Connections , Repairing Connector Terminals and Connector Repairs in Wiring Systems . Was a problem found? | -- | ||
10 |
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | -- | |
11 |
Is (traction control) desired torque at or near the specified value? | 100% | System OK |
