The ABS VI/ETS Antilock Braking System with the optional Enhanced Traction System (ETS) consists of the following components:

The conventional brake system includes the following components:

The ABS VI includes the following components:

The ABS VI with the optional ETS includes the following components:

The ABS Brake Modulator/Motor Pack Assembly controls hydraulic pressure to the following areas:

The ABS Brake Modulator/Motor Pack Assembly controls hydraulic pressure by modulating the hydraulic pressure. This action prevents wheel slip.

The basic ABS brake modulator configuration consists of the following components:

The ABS brake motor pack consists of the following components:

Refer to Base Brake System and Antilock Brake System in this section for more information.

Notice: There is no serviceable or removable PROM. The EBCM/EBTCM must be replaced as an assembly.

The Electronic Brake Control Module (EBCM) controls the ABS VI. A microprocessor controls the EBCM.

The inputs to the system include the following components:

The outputs include the following components:

A serial data line is provided for service diagnostic tools and assembly plant testing.

The EBCM monitors the speed of each wheel.

The EBCM controls the motors and the solenoids in order to reduce brake pressure to a particular wheel when the following conditions exist:

When the wheel regains traction, brake pressure increases until the wheel approaches slip again.

This cycle will repeat until one of the following conditions exists:

The front wheel speed sensors are of a variable reluctance type. Each sensor is attached to the knuckle assembly in close proximity to a toothed ring. An AC voltage is generated when the toothed ring passes by the sensor. The magnitude and frequency are proportional to the speed of the wheel and both will increase with increasing speed.

The sensor is not repairable.

The air gap is not adjustable.

The sensor and tooth ring cannot be serviced separately from the outer constant velocity (CV). If the ring is damaged, the outer CV joint must be replaced.

The rear wheel speed sensors operate in the same manner as the front wheel speed sensors. Refer to Front Wheel Speed Sensors.

However, the rear wheel speed sensors and the toothed ring are contained within the dust cap of the integral rear wheel bearing. This allows approved environmental protection and easier assembly.

The sensor and the toothed ring are not repairable.

The air gap cannot be adjusted.

The entire integral bearing and speed sensor unit must be replaced if a rear wheel speed sensor fails.

The Electronic Brake Control Relay is a normally-open contact type.

The Electronic Brake Control Relay has special contact material to handle the high currents required for the ABS VI/ETS operation.

The relay allows battery voltage and current to be supplied to the EBCM. The EBCM supplies power to the motors and the solenoids.

Refer to Fluid Level Switch in Hydraulic Brakes.

The wiring harness is the mechanism which electrically connects the EBCM to the following components:

The wiring harness consists of the following components:

A jumper harness located between each wheel speed sensor and the main wiring harness.

Each jumper harness is made of highly flexible twisted pair wiring.

The wiring exists because the main harness must connect to the suspension of the vehicle. Therefore, the wiring in this area is subjected to the same motion as a spring or a shock absorber. Any repair to this section of wiring will result in stiffening. Stiffening will eventually result in failure due to wire fatigue.

The wheel speed sensor jumper harnesses are not repairable and must be replaced. Do not attempt to solder, splice, or crimp the harnesses. Eventual failure will occur.

Refer to Wheel Speed Sensor Jumper Harness Replacement .

The Electronic Brake Control Module (EBCM) continuously monitors itself and other ABS/ETS components.

If the EBCM detects a problem with the system, the amber ABS warning indicator will light continuously (solid indicator) in order to alert the driver of the problem.

The amber ABS warning indicator flashes to warn the driver of an existing ABS malfunction which may have degraded the base brake performance. In this situation, the vehicle must be serviced immediately in order to regain full base and ABS operation.

A solid amber ABS warning indicator indicates that a problem has been detected. The problem is one that affects the operation of the ABS. In this situation, no antilock braking or enhanced traction will be available. Normal (non-antilock) brake performance will still be available.

The ABS VI/ETS must be serviced in order to regain ABS braking ability and enhanced traction (if equipped).

If the EBCM detects a malfunction with the ETS, the amber ETS OFF indicator will illuminate in order to alert the driver of the malfunction. In this situation, enhanced traction will not be available. The base braking will still be available.

The following indicators will illuminate any time when the EBCM suspects that the ABS operation is degraded because of a system malfunction:

The red BRAKE warning indicator illuminates when the following conditions exist:

The red BRAKE warning indicator alerts the driver that a base brake problem may exist.

The amber LOW TRAC indicator illuminates in order to alert the driver that the ABS is active. Whenever the EBCM determines that the vehicle has entered a braking event that requires the ABS, the amber LOW TRAC indicator will turn on. The amber LOW TRAC indicator will remain on for approximately 3 to 4 seconds after the ABS event is completed.

The amber LOW TRAC order to alert the driver of a low traction situation. The amber LOW TRAC informs the driver that the ETS is operating. The amber LOW TRAC indicator will remain on for approximately 3 to 4 seconds after the ETS event is completed.

When the EBCM receives power (the ignition is placed in the RUN position), the EBCM will command the LOW TRAC indicator to turn on for three seconds. This action is a bulb check procedure.

The power distribution system of the vehicle consists of the following components:

Refer to Power Distribution and Fuse Block Details in Electrical Diagnosis for fuse locations