2007 ISUZU KB P190 lock

5A -1 BR AKE CON TROL SY STE M
Brake (E BD) Warning Lamp ......................................................................................... 5 A -25
Tech 2 Scan Tool .......................................................................................................... 5 A -2 6
Da ta List ( T ech 2 ).......................................................................................................... 5 A -32
Diagnostic Trouble Codes ................................................................................................ 5 A -33
Diagnosis By " A BS" Warning Lamp Illumination Patter n.............................................. 5 A -35
Basic Diagnostic Flow Chart ............................................................................................ 5 A -38
Basic Inspec tion Procedure ............................................................................................. 5 A -40
1. Basic Inspec tion of Ser vice Brake .......................................................................... 5 A -40
2. Ground Inspection .................................................................................................... 5 A -40
W heel Speed Sensor Inspec tion Procedure.................................................................... 5 A -41
Symptom Diagnosis .......................................................................................................... 5A- 42
ABS Works Frequently But Vehicle Does Not Decelerate ......................................... 5A-42
Uneven Braking Occurs While ABS Works ................................................................ 5A-43
The Wheels Are Locked................................................................................................ 5A-43
Brake Pedal Feed Is Abnormal .................................................................................... 5A-44
Braking Sound (From EHCU) Is Heard While Not Braking ........................................ 5A-45
No ABS Warning Lamp ................................................................................................. 5A-46
ABS Warning Lamp ON Steady.................................................................................... 5A-47
DTC C0221 (Flash Code 21) Front Right Wheel Speed Sensor
Short Circuit or Circuit Open ......................................................................................... 5A-48
DTC C0222 (Flash Code 22) Front Right Wheel Speed Sensor Signal Malfunction..... 5A-50
DTC C0225 (Flash Code 25) Front Left Wheel Speed Sensor Short Circuit or
Circuit Open ................................................................................................................ .... 5A-52
DTC C0226 (Flash Code 26) Front Left Wheel Speed Sensor Signal Malfunction ....... 5A-54
DTC C0231 (Flash Code 31) Rear Right Wheel Speed Sensor Short Circuit or
Circuit Open ................................................................................................................ .... 5A-56
DTC C0232 (Flash Code 32) Rear Right Wheel Speed Sensor Signal Malfunction ...... 5A-58
DTC C0235 (Flash Code 35) Rear Left Wheel Speed Sensor Short Circuit or
Circuit Open ................................................................................................................ .... 5A-60
DTC C0236 (Flash Code 36) Rear Left Wheel Speed Sensor Signal Malfunction ........ 5A-62
DTC C0238 (Flash Code 38) Front Speed Sensor Correlation ....................................... 5A-64
DTC C0241 (Flash Code 41) Front Right Hold Solenoid Valve Circuit .......................... 5A-66
DTC C0242 (Flash Code 42) Front Right Release Solenoid Valve Circuit..................... 5A-66
DTC C0245 (Flash Code 45) Front Left Hold Solenoid Valve Circuit ............................. 5A-68
DTC C0246 (Flash Code 46) Front Left Release Solenoid Valve Circuit ....................... 5A-68

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

BRAKE CONTROL SYSTEM 5A-3


Service Precaution
WARNING: THIS VEHICLE HAS A SUPPLEMENTAL
RESTRAINT SYSTEM (SRS). REFER TO THE SRS
COMPONENT AND WIRING LOCATION VIEW IN
ORDER TO DETERMINE WHETHER YOU ARE
PERFORMING SERVICE ON OR NEAR THE SRS
COMPONENTS OR THE SRS WIRING. WHEN YOU
ARE PERFORMING SERVICE ON OR NEAR THE
SRS COMPONENTS OR THE SRS WIRING, REFER
TO THE SRS SERVICE INFORMATION. FAILURE TO
FOLLOW WARNINGS COULD RESULT IN
POSSIBLE AIR BAG DEPLOYMENT, PERSONAL
INJURY, OR OTHERWISE UNNECESSARY SRS
SYSTEM REPAIRS.


CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU/GM will call out those fasteners that require
a replacement after removal. ISUZU/GM will also
call out the fasteners that require thread lockers or
thread sealant. UNLESS OTHERWISE SPECIFIED,
do not use supplemental coatings (paints, greases,
or other corrosion inhibitors) on threaded fasteners
or fastener joint interfaces. Generally, such
coatings adversely affect the fastener torque and
the joint clamping force, and may damage the
fastener. When you install fasteners, use the
correct tightening sequence and specifications.
Following these instructions can help you avoid
damage to parts and systems.


BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

5A-4 BRAKE CONTROL SYSTEM
General Description
EHCU has controlled ABS (Anti-lock Brake System) and
EBD (Electronic Brake-force Distribution System). ABS
works on all four wheels. EBD system works on rear 2
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 Control Unit.













This illustration is based on RHD model

RTW 75AMF001101
Legend
(1) Electronic (6) Front Left W heel Speed Sensor
(2) Hydraulic (7) Rear Right W heel Speed Sensor
(3) Hydraulic Unit (H/U) (8) Rear Left W heel Speed Sensor
(4) Control Unit (9) G sensor (4W D only)
(5) Front Right W heel Speed Sensor (10) 2-4W D Control Unit (4W D only)


BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

BRAKE CONTROL SYSTEM 5A-7
Normal Braking
During normal (non anti-lock) braking, the solenoid
valve has current flow.
Brake fluid travels through the center of the inlet valve
around the outlet valve then to the brake pistons.

RTW 75AMF000201
Legend
(1) Master Cylinder (5) Brake
(2) Brake Pedal (6) Outlet Valve
(3) Motor and Pump (7)Inlet Valve
(4) Accumulator



BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

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



BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

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



BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

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



BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

5A-22 BRAKE CONTROL SYSTEM
System Components
Electronic Hydraulic Control Unit (EHCU), four W heel
Speed Sensors, two W arning Lamps, and G sensor.

Electronic Hydraulic Control Unit (EHCU)
The EHCU consists of ABS control circuits, fault
detector, and a fail-safe. It drives the EHCU according
to the signal from each sensor, cancelling ABS to return
to normal braking when a malfunction has occurred in
the ABS.
The EHCU has a self-diagnosing function which can
indicate faulty circuits during diagnosis.
The EHCU is mounted on the engine compartment rear
left side. It consists of a motor, solenoid valves and a
fail safe relay.
Solenoid Valves: Reduces or holds the caliper fluid
pressure for each front brake or both rear brakes
according to the signal sent from the EHCU.
Buffer chamber: Temporarily holds the brake fluid that
returns from the front and rear brake so that pressure of
front brake can be reduced smoothly.
Motor: Drives the pump according to the signal from
EHCU.
Fail safe Relay: W hen failure occurs in ABS.
The power supply to solenoid Valve is cut.

ABS Warning Lamp


RTW 75ASH000101
Vehicles equipped with the Anti-lock Brake System
have an amber “ABS” warning lamp on the instrument
panel. The “ABS” warning lamp will illuminate if a
malfunction in the Anti-lock Brake System is detected
by the Electronic Hydraulic Control Unit (EHCU). In the
case of an electronic malfunction, the EHCU will turn
“ON” the “ABS” warning lamp and disable the anti-lock
braking function.

The “ABS” warning lamp will turn “ON” for
approximately three seconds after the ignition switch is
in the “ON” position.
If the “ABS” warning lamp stays “ON” after the ignition
switch is in the “ON” position, or comes “ON” and stays
“ON” while driving, the Anti-lock Brake System should
be inspected for a malfunction according to the
diagnostic procedure.

Wheel Speed Sensor (WSS)
It consists of a sensor and a rotor. The sensor is
attached to the knuckle on the front wheels and to the
rear wheels.
The rotor is press-fit in the axle shaft.

G Sensor
The G sensor detects the vehicle deceleration speed
and sends a signal to the EHCU. In 4W D operation, all
four wheels may be decelerated in almost the same
phase, since all wheels are connected mechanically.
This tendency is noticeable, particularly on roads with
low friction coefficient, and the ABS control is adversely
affected.
The G sensor judges whether the friction coefficient of
the road surface is low or high, and changes the
EHCU's operating system to ensure ABS and EBD
control.

Normal and Anti-lock Braking
Under normal driving conditions, the Anti-lock Brake
System functions the same as a standard power
assisted brake system. However, with the detection of
wheel lock-up, a slight bump or kick-back will be felt in
the brake pedal. This pedal “bump” will be followed by a
series of short pedal pulsations which occurs in rapid
succession. The brake pedal pulsation will continue
until there is no longer a need for the anti-lock function
or until the vehicle is stopped. A slight ticking or popping
noise may be heard during brake applications when the
anti-lock feature is being used.
W hen the anti-lock feature is being used, the brake
pedal may rise even as the brakes are being applied.
This is also normal. Maintaining a constant force on the
pedal will provide the shortest stopping distance.




BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007