Isuzu Rodeo UE. Manual - part 95

5A–3

BRAKE CONTROL SYSTEM

General Description

The Anti-lock Brake System (ABS) works on all four
wheels. A combination of wheel speed sensor and
Electronic Hydraulic Control Unit (EHCU) can determine
when a wheel is about to stop turning and adjust brake
pressure to maintain best braking.

This system helps the driver maintain greater control of
the vehicle under heavy braking conditions.

NOTE: The Electronic Hydraulic Control Unit (EHCU)
comprises the Hydraulic Unit (H/U) and the coil Integrated
Module.

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Legend

(1) Electronic
(2) Hydraulic
(3) Hydraulic Unit (H/U)

(4) Coil Integrated Module
(5) Front Wheel Speed Sensor
(6) Rear Wheel Speed Sensor
(7) Proportioning and Bypass (P&B) Valve

5A–4

BRAKE CONTROL SYSTEM

Functional Description

Hydraulic Unit (H/U)

Solenoid Valve

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Legend

(1) Isolation Valve
(2) Dump valve

5A–5

BRAKE CONTROL SYSTEM

Normal Braking
During normal (non anti-lock) braking, the solenoid valves
are without current and closed due to spring force.

Brake fluid travels through the centre of the normally open
isolation valve around the normally closed dump valve
and on to the brake pistons.

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Legend

(1) Brake
(2) Master Cylinder

5A–6

BRAKE CONTROL SYSTEM

Pressure Isolation (Pressure Maintain)
The electro-hydraulic control unit is activated when the
brakes are applied which sends a signal to the coil
integrated module to prepare for a possible anti-lock stop.
If the information from the wheel speed sensors indicates
excessive wheel deceleration (imminent lockup), the first
step in the anti-lock sequence is to isolate the brake
pressure being applied by the brake pedal.

The microprocessor in the coil integrated module sends a
voltage to the coil to energize and close the isolation
valve. This prevents any additional fluid pressure applied
by the brake pedal from reaching the wheel. With the
isolation valves closed, further unnecessary increase in
the brake pressure is therefore prevented.

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Legend

(1) Brake
(2) Master Cylinder