Hino 600, Workshop Manual, Page: 392 / 451

ABS (ABS : HYDRAULIC (E VERSION)) BR03–8
OVERVIEW AND FUNCTION
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ABS ECU (INTEGRATED WITH ABS MODULATOR)
Based on pulse signals from the wheel sensors, the ABS ECU mounted in
the vehicle calculates and evaluates the slip ratio and the acceleration/
deceleration speed of the wheels. Based on the results, it sends signals to
the modulator assembly as necessary, causing them to operate and apply
the brakes to maintain the slippage of the wheels within the optimal range.
During braking, the fluid pressure applied to the brake cylinder is regulated
to prevent the wheels from locking. The brakes are applied so as to main-
tain the slippage of the wheels within the optimal range.
Regardless of whether the vehicle is stopped or being driven, and whether
or not the brakes are being applied, the circuit consisting of the wheel sen-
sors, modulator assembly, ABS ECU, and wire harnesses are constantly
being checked by the ABS ECU’s fail-safe circuit. If some sort of malfunc-
tion occurs, the fail-safe circuit warns the driver by lighting the ABS warning
light. At the same time, the ABS system that is experiencing the malfunc-
tion is shut off and braking is restored to normal (non-ABS) operation.
ABS MODULATOR ASSEMBLY
1. Overview
•
The ABS modulator is mounted between the Hydro booster and disc
brake caliper. It controls the fluid pressure to the disc brake caliper,
regulating the pressure according to signals from the ABS ECU in
three modes: pressure maintenance, pressure reduction, and pres-
sure increase.
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