Warning Light Operation

GENERAL INFORMATION.

1. When the ignition is switched on (before starting the engine), the "ABS" warning light illuminates and goes out after 3 seconds. At the same time, the "BRAKE" warning light comes on and quickly goes out.

2. When the starter is engaged, both the red "BRAKE" and yellow "ABS" warning lights must

remain on continuously.

3. After the engine starts, the "BRAKE" warning light must go out immediately, and the "ABS" warning light must go out after 3-4 seconds.

The size of the tires installed on the vehicle is very important from the standpoint of

ABS operation. When replacing tires, use only tires

that are identical in size, load rating, construction and other

performance characteristics to the original tires fitted to

the new vehicle. Pay attention to the standard

tire markings. Replace tires only in complete axle sets. Installing other tires on the vehicle may seriously affect ABS operation. The ABS consists of the standard brake system and additional components. The brake system includes the vacuum booster, master cylinder, front disc brake assemblies, rear drum brakes with leading and trailing shoes, brake lines and hoses, and the brake fluid level

fluid level sensor and the "BRAKE" warning light. The additional ABS components include:

hydraulic modulators with electromechanical actuators, ECU, power relay.

two actuator fuses, four wheel speed sensors (one at each wheel), electrical wiring, control unit.

warning light and the "ABS" warning light.

The modulator and electromechanical actuator include a housing, piston,

ball screw drive, check valve, solenoid valve (front wheels only),

electric motor, brake spring and gear train. The modulator

is designed to regulate brake fluid pressure in the wheel cylinder. Braking control of individual wheels is performed by the microprocessor ECU. Signals from the wheel speed sensors,

brake light switch and ignition switch. Power supply to the ABS actuating components

is supplied from the ECU and battery through a relay, which the ECU controls. To the

output of the ECU are connected three modulator motors, two solenoid valves, the ABS actuator power relay and the diagnostic connector. The ECU serial data line is connected to terminal M of the diagnostic connector and provides transmission of diagnostic information when checking system operation. The ECU

monitors the wheel speeds of all four wheels. If, with the brake

pedal depressed (brake light on), one of the wheels begins to lock, the ECU commands the corresponding modulator to reduce brake fluid pressure in the wheel cylinder of that wheel. At the same time the solenoid valve and the actuator motor are energized.

modulator. After wheel slip is reduced, the ECU commands

an increase in wheel cylinder pressure and monitors the change in wheel speed. If slip increases, the ECU again commands release

of the wheel. These pressure control cycles repeat until

the vehicle stops or the brake pedal is released, or until

there is no longer a risk of braking wheel lock. In addition to its direct

control functions, the ECU performs self-diagnosis and diagnosis of all sensors and actuators connected to its inputs and outputs. When any ABS fault is detected, the ECU sets the corresponding diagnostic trouble code and stores it in non-volatile memory (ROM), where the information is retained even when power is disconnected.

Warning.

The ECU is not serviceable. If it fails, replace the unit as a complete assembly..

The inductive front wheel speed sensor is mounted on the steering knuckle of the front suspension strut. The magnetic core of the sensor is positioned with a small air gap from the toothed ring, which rotates together with the front wheel. As the ring rotates, an alternating EMF is induced in the sensor coil. The amplitude and

frequency of the sensor signal depend on vehicle speed and increase with it. The sensor signal frequency is proportional to vehicle speed..

The wheel speed sensor is non-serviceable. The air gap between the sensor core and the toothed ring is not adjustable during operation..

The toothed ring with 47 evenly spaced teeth is pressed onto the housing of the outer constant velocity joint of the front wheel drive shaft. When

performing maintenance or repair of the front suspension or drive shafts, take care not to damage or break the teeth of the ring..

If the ring teeth are damaged, replace the outer constant velocity joint of the front wheel drive shaft..

The rear wheel speed sensor operates in the same way as the front sensor. The sensor and toothed ring are integrated into the rear wheel hub assembly. If the sensor or toothed ring is damaged, replace the hub assembly..

The normally open relay is designed for the high current required to

supply the ABS actuators. On command from the ECU, the relay connects

the battery to the input of the unit that controls power supply to

the modulator motors and modulator solenoid valves. The relay is located on the right side of the engine compartment, near the hydraulic modulator unit mounted on the splash shield. During operation, the ECU continuously performs self-diagnosis and diagnosis of

ABS peripheral devices. When an ABS malfunction is detected, the yellow "ABS" warning lamp

"ABS" starts flashing or stays on continuously, warning the driver of a malfunction. The warning lamp

flashes if the fault does not immediately disable the ABS. However, if the "ABS" lamp is flashing, check the system and correct the faults at the first opportunity.

system and correct the faults. If a serious fault occurs that prevents normal ABS operation, the "ABS" warning lamp stays on continuously..

Braking with the ABS operating is not possible. However, the brake

system can operate in basic braking mode (without ABS activation). In this case, determine the cause of the fault and repair the ABS..

The red "BRAKE" warning lamp comes on in the following cases: brake fluid level falls below the minimum, parking brake is applied, with

ignition on and engine off, or on command from the ECU. The ECU turns on the "BRAKE" lamp when ABS faults occur that may affect

braking system operation. In this case the ECU stores the corresponding fault code, code A086 for activation of the "BRAKE" lamp, and

switches off the ABS..

The electronic device switches off the "ABS" lamp on command from the ECU. Until

the command from the ECU is received, the "ABS" lamp remains on..

Warning.

Brake fluid may cause eye and skin irritation. If

brake fluid contacts exposed skin, take the following measures. If fluid gets in the eyes, rinse thoroughly with water. If it contacts the skin, wash with soap and water. If swallowed, seek medical attention immediately.

Seek medical attention.

Avoid getting brake fluid drops on painted body surfaces, electrical wire insulation, and wiring connectors and electrical equipment. Brake fluid can damage

paint finish and electrical wiring. If brake fluid gets on these parts, rinse the area with water.