Engine torque reduction
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2004 GMC Yukon XL, 2004 GMC Yukon, 2004 Chevrolet Tahoe, 2004 Chevrolet Suburban, and 2004 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The EBCM uses a 5-volt pulse width modulated (PWM) signal to request that the PCM reduce the amount of torque to the drive wheels. The PCM reduces torque to the drive wheels by retarding spark timing and commanding the throttle actuator control. The PCM uses a 12-volt PWM signal to report to the EBCM the amount of torque that is being delivered to the drive wheels. Engine torque reduction is mostly used to reduce vehicle speed during VSES events and during TCS events when the brakes are in danger of being overheated or all of the driven wheels are slipping at the same rate. Engine torque reduction can be disabled by pressing the traction control switch.