The ABS VI Antilock Braking System consists of the following components:

The conventional brake system includes the following components:

The ABS VI includes the following components:

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

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

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 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 serial data line is located in terminal 9 of the Data Link Connector (DLC).

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 lock-up again.

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

The EBCM monitors the following components for proper operation:

If a system malfunction is detected, the EBCM will store a DTC in nonvolatile memory (i.e., the DTC will not disappear if the battery is disconnected.)

Refer to Diagnostic System Check for more information.

Each of the front wheel speed sensors consists of a variable reluctance sensor.

The sensor and the toothed ring are part of the sealed hub and bearing unit. Being part of the sealed hub and bearing unit allows improved environmental protection and easier assembly.

When teeth pass by the sensor, the sensor generates an AC voltage that has a frequency proportional to the speed of the wheel.

The sensor is not repairable.

The air gap is not adjustable.

The sensor and the toothed ring cannot be serviced separately from the hub and bearing assembly.

The entire integral bearing/sensor unit must be replaced if a front wheel speed sensor fails.

Refer to Wheel Speed Sensor Replacement or to Wheel Speed Sensor Replacement .

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

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.

Refer to Wheel Speed Sensor Replacement .

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 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 or to Wheel Speed Sensor Jumper Harness Replacement .

Caution: The braking system may not be working properly if the ABS warning indicator is flashing. Driving with a flashing ABS warning indicator can lead to an accident. If the ABS warning indicator is flashing, pull safely off the road and have the vehicle towed for service.

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

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

The amber ABS warning indicator will flash if the EBCM attempts to turn on following indicators at the same time, but is unable to do so:

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 traction control will be available. Normal (non-antilock) brake performance will still be available.

The ABS VI must be serviced in order to regain ABS braking ability and electronic traction control (if equipped).

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

When the EBCM receives power (the ignition is placed in the RUN or the START position), the EBCM will command the LOW TRACTION 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:

Fusible links are short pieces of wire that are several sizes smaller than the circuit wire that supply power. They are covered with special high temperature insulation.

When the fusible links are conducting an improperly high current flow, they will melt and stop the current flow.

The fusible links are designed to protect the vehicle's electrical system from the electrical shorts in the circuits that are not protected by the circuit breakers or fuses.

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