Electronic Brake & Traction Control Module (EBTCM)
The Electronic Brake and Traction Control Module (EBTCM) is a small control computer, mounted behind the Control Panel, which monitors the speed of each wheel as well as several functions internal to the BPM valve. See Fig 1.
The primary functions of the EBTCM are to detect wheel locking and wheel slip tendencies, control the brake system while in anti-lock mode or traction control mode, and monitor the system for proper operation. The EBTCM communicates torque requests (PWM signals) and receives delivered torque (PWM signals) from the Powertrain Control Module (PCM). The EBTCM also communicates TCS Diagnostic Trouble Codes while in diagnostic mode to the BCM via serial data.
The EBTCM continuously checks the speed of each wheel to determine if any wheel is beginning to lock or slip. If a wheel locking tendency is detected, the EBTCM commands appropriate valve solenoid positions to modulate brake fluid pressure in some or all of the hydraulic circuits to prevent wheel lock-up and provide optimum braking. The EBTCM continues to control pressure in individual hydraulic circuits until a locking tendency is no longer present.
If the EBTCM detects that a wheel is beginning to slip or lose traction in one of the front wheels, it will apply the brake to that wheel to bring it to any acceptable slip rate: The EBTCM will command the appropriate valve solenoid position in the BPM valve and modulate brake fluid pressure in one or both front hydraulic circuits until the tendency for the wheel slip is no longer detected.
The Anti-Lock Brake and Traction Control Systems are constantly monitored by the EBTCM for proper operation. If the EBTCM detects a loss of serial data, it can disable the anti-lock and traction control functions and turn on the red BRAKE warning lamp in the Instrument Panel Cluster (IPC).
To assure proper braking performance it is important that the EBTCM always have a clean and tight ground of less than 1 ohm resistance.