DTC P1689: Traction Control Delivered Torque Output Circuit: Description

The Electronic Brake Control Module (EBCM) and PCM simultaneously controls the traction control. PCM reduces amount of torque supplied to drive wheels by retarding spark timing and selectively turning off fuel injectors. EBCM actively applies brakes to front wheels in order to reduce torque.

EBCM sends a requested torque message via a Pulse Width Modulated (PWM) signal to PCM. The duty cycle of the signal is used to determine how much engine torque EBCM is requesting PCM to deliver. Normal values are between 10-90 percent duty cycle. The signal should be at 90 percent when traction control is not active and at lower values during traction control activations. PCM supplies a pull-up voltage of 5 volts that EBCM switches to ground to create the signal.

PCM sends a delivered torque message via a PWM signal to EBCM. The duty cycle of signal is used to determine how much engine torque PCM is delivering. Normal values are between 10-90 percent duty cycle. The signal should be at low values (around 10 percent) at idle and higher values under driving conditions. EBCM supplies a pull-up voltage of 12 volts that PCM switches to ground to create the signal.

When certain PCM DTCs are set, PCM will not be able to perform the torque reduction portion of traction control. A serial data message is sent to EBCM indicating that traction control is not allowed.