Page 601 of 6020
5A-8 BRAKE CONTROL SYSTEM
Pressure Isolation (Pressure Maintain)
The electronic-hydraulic control unit is activated when
the brakes are applied.
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 Control Unit sends a voltage
to the coil to energize and close the outlet valve. This
prevents any additional fluid pressure applied by the
brake pedal from reaching the wheel. W ith the outlet
valves closed, unnecessary increase in the brake
pressure is prevented.
RTW 75AMF000301
Legend
(1) Master Cylinder (5) Brake
(2) Brake Pedal (6) Outlet Valve
(3) Motor and Pump (7)Inlet Valve
(4) Accumulator
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ISUZU KB P190 2007
Page 602 of 6020
BRAKE CONTROL SYSTEM 5A-9
Pressure Reduction
Once the brake pressure is isolated, it must be reduced
to allow the wheels to unlock. This is accomplished by
dumping a portion of the brake fluid pressure into the
accumulator.
The microprocessor activates the normally closed outlet
valve to open, allowing fluid from the wheels to be
dumped into the accumulator. This is done with very
short activation pulses opening and closing the outlet valve passageway. Brake pressure is reduced at the
wheel and allows the wheel to begin rotating again. The
fluid from the brake piston is stored in the accumulator
against spring pressure and a portion of this fluid also
primes the pump.
The outlet valves are operated independently to control
the deceleration of the wheel.
RTW 75AMF000401
Legend
(1) Master Cylinder (5) Brake
(2) Brake Pedal (6) Outlet Valve
(3) Motor and Pump (7)Inlet Valve
(4) Accumulator
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ISUZU KB P190 2007
Page 603 of 6020
5A-10 BRAKE CONTROL SYSTEM
Brake Release
At the end of the anti-lock stop, when the brake pedal is
released, the pump will remain running for a short time
to help drain any fluid from the accumulator. As this fluid
returns into the system, the spring forces the piston back to its original position.
The inlet valve opens and fluid may return to the master
cylinder. Conventional braking is then resumed.
RTW 75AMF000501
Legend
(1) Master Cylinder (5) Brake
(2) Brake Pedal (6) Outlet Valve
(3) Motor and Pump (7)Inlet Valve
(4) Accumulator
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ISUZU KB P190 2007
Page 604 of 6020
BRAKE CONTROL SYSTEM 5A-11
Circuit Diagram
With 4JA1 engine
RTW 78AXF007201
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Page 605 of 6020
5A-12 BRAKE CONTROL SYSTEM
With HFV6 engine
RTW 78AXF012801
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Page 606 of 6020
BRAKE CONTROL SYSTEM 5A-13
Except with 4JA1, HFV6 engine
RTW 78AXF018701
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ISUZU KB P190 2007
Page 607 of 6020
5A-14 BRAKE CONTROL SYSTEM
Connector List
No. Connector face No. Connector face
B-23
White
Meter-A C-36
SilverEngine room - LH ; Ground
B-24
White
Meter-B C-44
WhiteStoplight switch
B-48
Black
G sensor C-53
OrangeABS sensor Front-RH
B-54
White
J/B I2 C-54
OrangeABS sensor Front-LH
B-56
White
J/B I4 C-67
Black
EHCU
B-58
Black
Data link connector C-107
WhiteJ/B E2
B-62
White
Ignition switch (IGSUB : G1) C-108
WhiteJ/B E1
B-63
White
Ignition switch (IGSUB : G2) C-109
SilverBody-LH ; ground
B-82
Silver
W eld splice 6 (Ground) C-111
BlackTransfer case control module
C-2
Silver
Engine room - RH ground F-4
Gray ABS sensor
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ISUZU KB P190 2007
Page 608 of 6020
BRAKE CONTROL SYSTEM 5A-15
No. Connector face No. Connector face
H-6
White
Engine room ~ INST P-7
Battery (ALT)
H-7
White
Engine room ~ INST P-10
SilverEngine ground
H-9
White
Engine room ~ Chassis P-11
SilverFuse & relay box
H-15
White
Engine room ~ Chassis
H-18
White
Engine room ~ INST
H-48
White
Engine room ~ INST
P-1
Silver
Battery (+)
P-2
Silver
Relay & Fuse box
P-5
Silver
Battery (-)
P-6
Silver
Body ground
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ISUZU KB P190 2007