The Electro-Hydraulic Control Unit (EHCU) consists of the Electronic Brake Control module (EBCM) and the Brake Pressure Modulator Valve (BPMV). The EHCU regulates hydraulic pressure in the brake system in order to prevent wheel slip (lock up).

The EBCM is the electronic portion of the EHCU. The EBCM receives and processes sensor and switch inputs and then controls BPMV function if it is necessary to respond to these inputs. Inputs to the EBCM include the following items:

EBCM outputs include the following items:

The EBCM communicates with the scan tool via a UART serial data circuit which directly connects the EBCM to the Diagnostic link connector (DLC). The EBCM also uses the class 2 serial data circuit in order to provide the PCM/VCM with data required to perform misfire detection.

The Brake Pressure Modulator Valve (BPMV) is the hydraulic/mechanical portion of the EHCU, consisting of a valve body and pump motor. The EBCM controls the BPMV in order to regulate hydraulic pressure in the following brake circuits:

Each circuit within the BPMV has an isolation valve and a dump valve. These valves are used to hold, decrease or increase hydraulic pressure in the brake circuits. There are 2 low pressure accumulators located within the BPMV, which are used to store brake fluid in the unit during an ABS event. The pump is used to return fluid from the accumulators to the master cylinder or fluid reservoir.

The front wheel speed sensors are a magnetic coil/pickup type. Each WSS produces an AC voltage signal which is received by the EBCM. The AC voltage is produced as teeth on a toothed ring pass through the magnetic field of the WSS pole piece. The frequency of the AC signal is used to calculate the wheel speed. The rear wheel speed signal originates at the vehicle speed sensor (VSS) and is supplied to the EBCM by the Vehicle Control Module (VCM) or the Powertrain Control Module (PCM).