brake sensor ISUZU AXIOM 2002 Service Owner's Guide

5A±30BRAKE CONTROL SYSTEM
Symptom Diagnosis
The symptoms that cannot be indicated by warning light
can be divided in the following five categories:
1. ABS works frequently but vehicle does not
decelerate.
2. Uneven braking occurs while ABS works.
3. The wheels lock during braking.
4. Brake pedal feel is abnormal.
5. Braking sound (from EHCU) is heard while not
braking.
These are all attributed to problems which cannot be
detected by EHCU self-diagnosis. Use the customer
complaint and test to determine which symptom is
present. Then follow the appropriate flow chart listed
below.
NoSymptomDiagnostic Flow ChartsNo.Sym tomWithout TECH 2With TECH 2
1ABS works frequently but vehicle does not decelerate.Chart A-1Chart TA-1
2Uneven braking occurs while ABS works.Chart A-2Chart TA-2
3The wheels are locked.Chart A-3Chart TA-3
4Brake pedal feel is abnormal.Chart A-4Ð
5Braking sound (from EHCU) is heard while not braking. Chart A-5Chart TA-5
Chart A-1 ABS Works Frequently But Vehicle Does Not Decelerate
StepActionYe sNo
1Is braking force distribution normal between front and rear of
vehicle?
Go to Step 2
Repair brake
parts.
Go to
Step 7
2Are axle parts installed normally?
Go to Step 3
Repair axle parts.
Go to
Step 7
3Is there play in each or any wheel speed sensor?Repair wheel
speed sensor.
Go to
Step 7Go to Step 4
4Is there damage, or powdered iron sticking to each or any wheel
speed sensor/sensor ring?Replace or repair
sensor or sensor
ring.
Go to
Step 7Go to Step 5
5Is the output of each wheel speed sensor normal? (Refer to Chart
C-1 or TC-1
)
Go to Step 6
Replace wheel
speed sensor or
repair harness.
Go to
Step 7
6Is the input of TOD control unit normal?
Go to Step 7
Replace TOD
control unit or
repair harness.
Go to
Step 7
7Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the ªBasic
diagnostic flow
chartº
Go to Step 7

5A±31
BRAKE CONTROL SYSTEM
Chart TA-1 ABS Works Frequently But Vehicle Does Not Decelerate (Use TECH 2)
StepActionYe sNo
11. Connect TECH 2.
2. Make sure of the output conditions of each sensor.
Is the output of each sensor normal?
Go to Step 2
Replace wheel
speed sensor.
Go to
Step 3
2Return to Chart A-1.
Was the Chart A-1 finished?
Go to Step 3Go to Step 2
3Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the ªBasic
diagnostic flow
chartº
Go to Step 3
Chart A-2 Uneven Braking Occurs While ABS Works
StepActionYe sNo
1Is there play in each or any sensor?Repair.
Go to
Step 5Go to Step 2
2Damage or powdered iron sticking to each or any sensor/sensor
ring?Repair.
Go to
Step 5Go to Step 3
3Is the output of each sensor normal? (Refer to Chart C-1 or TC-1)
Go to Step 4
Replace sensor
or repair harness.
Go to
Step 5
4Is brake pipe connecting order correct?
Replace H/U.
Go to
Step 5
Reconnect brake
pipe correctly.
Go to
Step 5
5Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the ªBasic
diagnostic flow
chartº
Go to Step 5
Chart TA-2 Uneven Braking Occurs While ABS Works (Use TECH 2)
StepActionYe sNo
11. Connect TECH 2.
2. Make sure of the output conditions of each sensor.
Is the output of each sensor normal?
Go to Step 2Go to Step 3
2Check piping by TECH 2 ACTUATOR TEST
Is the piping normal?Replace EHCU.
Go to
Step 4
Repair the pipe.
Go to
Step 4
3Repair and check the wheel speed sensor (Refer to Chart B-20 to
B-23 , C-1 or TC-1
).
Was the each chart finished?
Go to Step 4Go to Step 3
4Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the ªBasic
diagnostic flow
chartº
Go to Step 4

5A±32BRAKE CONTROL SYSTEM
Chart A-3, TA-3 The Wheels Are Locked
StepActionYe sNo
1Is ABS working?Go to Step 2Go to Step 4
2Is vehicle speed under 10 km/h (6mph)?Go to Step 3Normal.
3Is sensor output normal? (Chart C-1 or TC-1)
Go to Step 4
Replace sensor
or repair harness.
Go to
Step 6
4Is front TOD control unit normal?
Go to Step 5
Replace TOD
control unit or
repair harness.
Go to
Step 6
5Is hydraulic unit grounded properly?Replace EHCU.
Go to
Step 6
Repair.
Go to
Step 6
6Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the ªBasic
diagnostic flow
chartº
Go to Step 6
Chart A-4 Brake Pedal Feed Is Abnormal
StepActionYe sNo
1Is the stop light actuated when the brake pedal is depressed?Go to Step 2Go to Step 3
21. Turn the ignition switch off.
2. Disconnected EHCU connector.
Is the check voltage EHCU connector terminals 13 to 7 when
brake pedal is depressed than battery voltage?
Go to Step 4
Harness NG
between brake
SW and EHCU.
Go to
Step 6
3Is stop light fuse normal?
Go to Step 5
Replace stop light
fuse.
Go to
Step 6
4Is the check continuity between EHCU connector terminals, 7 to
body grounded?
Go to Step 6
Repair body
grounded
harness.
Go to
Step 6
5Is brake SW normal?Repair stop light
harness.
Go to
Step 6
Replace brake
SW.
Go to
Step 6
6Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the ªBasic
diagnostic flow
chartº
Go to Step 6

5A±33
BRAKE CONTROL SYSTEM
Chart A-5, TA-5 Braking Sound (From EHCU) Is Heard While Not Braking
StepActionYe sNo
1Is this the first vehicle start after engine start?Normal.
(It is self
checking sound.)
Go to Step 2
2Is vehicle speed under 10 km/h (6 mph)?Normal.
(It is self
checking sound.)
Go to Step 3
3Check for the following condition:

At the time of shift down or clutch operation.

At the time of low road friction drive (ice or snow road) or rough
road drive.

At the time of high-speed turn.

At the time of passing curb.

At the time of operating electrical equipment switches.

At the time of racing the engine (over 5000 rpm).
Did it occur under any one condition above?
ABS may
sometimes be
actuated even
when brake pedal
is not applied.
Go to Step 4
4Is there play in each or any sensor/wheel speed sensor rings?Repair.
Go to
Step 7Go to Step 5
5Damage or powdered iron sticking to each or any sensor/wheel
speed sensor ring?Repair.
Go to
Step 7Go to Step 6
6Is each sensor output normal? (Refer to Chart C-1 or TC-1).Check harness/
connector for
suspected
disconnection
If no
disconnection is
found, replace
Coil integrated
module.
Go to
Step 7
Repair.
Go to
Step 7
7Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the ªBasic
diagnostic flow
chartº
Go to Step 7

5A±34BRAKE CONTROL SYSTEM
Diagnostic Trouble Codes
Choose and trace an appropriate flowchart by the
numbers listed below to find fault and repair.
Code
ChartFlash outSerial
CommunicationsDiagnosisItemChart
No.
12ÐÐÐÐ
13C02852 WD Controller in 4WD Vehicle ControllerWiringB-8
14C0271RAM read/write error
C0272ROM checksum errorCoil
C0270ALU function error
Coil
Integrated
Mdl
B-2
C0273Inoperative isolation itemModule
C0284Loop time overrun
15C0277Low ignition voltageWiringB-3C0278High ignition voltageWiringB-3
17C0269Excessive dump timeB-4
18C0274Excessive isolation timeCoil
IntegratedB-5
21C0276G-Sensor FailureIntegrated
ModuleB-6
22C0281Brake switch FailureB-7
24C0282Open or shorted 4y4 input signal (4WD only)WiringB-8
32C0267Open motor circuit or shorted ECU outputMotorB-9C0268Stalled motor or open ECU outputMotorB-9
35C0265Open relay circuitRelayB-10C0266Shorted relay circuitRelayB-10
41C0245FL Open isolation solenoid or shorted ECU outputB-11C0247FL Shorted isolation solenoid or open ECU outputB-11
42C0246FL Open dump solenoid or shorted ECU outputB-12C0248FL Shorted dump solenoid or open ECU outputB-12
43C0241FR Open isolation solenoid or shorted ECU outputB-13C0243FR Shorted isolation solenoid or open ECU outputSolenoid
B-13
44C0242FR Open dump solenoid or shorted ECU outputSolenoid
B-14C0244FR Shorted dump solenoid or open ECU outputB-14
45C0251Rear Open isolation solenoid or shorted ECU outputB-15C0253Rear Shorted isolation solenoid or open ECU outputB-15
46C0252Rear Open dump solenoid or shorted ECU outputB-16C0254Rear Shorted dump solenoid or open ECU outputB-16

5A±35
BRAKE CONTROL SYSTEM
Code
Chart
No. Item Diagnosis
Flash outChart
No. Item Diagnosis
Serial
Communications
51C0225FL Open or shorted sensorB-17
52C0221FR Open or shorted sensorB-18
53C0235Rear Open or shorted sensorB-19
61C0226FL Missing sensor signalB-20C0227FL Sensor signal dropoutSensor or
B-20
62C0222FR Missing sensor signalWiring
B-21C0223FR Sensor signal dropoutB-21
63C0236Rear Missing sensor signalB-22C0237Rear Sensor signal dropoutB-22
64C0229Simultaneous dropout of front sensor signalB-23
65C0238Wheel speed errorVehicle or
SensorB-24
ÐC0286Shorted indicator lampWiringÐ

5A±40BRAKE CONTROL SYSTEM
Chart B-3 Low or High Ignition Voltage (DTC 15 (Flash out) / C0277, 0278 (Serial
communications))
StepActionYe sNo
1Is the battery voltage normal? (Battery capacity check)
Go to Step 2
Charge or
replace battery.
Go to
Step 2
21. Turn the key off.
2. Disconnect coil integrated module connector.
3. Turn the key on.
Is the voltage between coil integrated module connector (C-6)
terminals 1 and 7, higher than 10V?Check harness
connector for
suspected
disconnection
Fault found:
Repair, and
perform system
self-check
No fault found:
replace EHCU.
Go to
Step 3
Repair harness or
connector.
Go to
Step 3
31. Reconnect all components, ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 3
Chart B-4 Excessive Dump Time (DTC 17 (Flash out) / C0269 (Serial communications))
StepActionYe sNo
1Check for anything causing extended ABS activation, such as
locked brakes or an erratic speed sensor signal.
Was a problem found?
Repair or
Replace
Go to Step 2
21. The key turned off.
2. Replace EHCU.
3. Reconnect all components, ensure all components are
properly mounted.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 2
Chart B-5 Excessive Isolation Time (DTC 18 (Flash out) / C0274 (Serial communications))
StepActionYe sNo
1Check for anything causing extended ABS activation, such as
locked brakes or an erratic speed sensor signal.
Was a problem found?
Repair or
Replace
Go to Step 2
21. The key turned off.
2. Replace EHCU.
3. Reconnect all components, ensure all components are
properly mounted.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 2

5A±41
BRAKE CONTROL SYSTEM
Chart B-6 G-Sensor Output Failure (DTC 21 (Flash out) / C0276 (Serial communications))
StepActionYe sNo
11. Turn the key off.
2. Replace EHCU.
3. Reconnect all components, ensure all components are
properly mounted.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 1
Chart B-7 Brake Switch Failure (DTC 22 (Flash out) / C0281 (Serial communications))
StepActionYe sNo
1Is the stop light actuated when the brake pedal is depressed?Go to Step 2Go to Step 4
21. Turn the key off.
2. Disconnected coil integrated module connector.
Is the check voltage between coil integrated module connector
(C-6) terminals 13 to 7 when brake pedal is depressed the battery
voltage?
Go to Step 3
Harness between
brake SW and
coil integrated
module is faulty.
Go to
Step 6
3Is the check that pins C-5 connector 2, and C-6 connector 7 have
good ground?Check harness /
connector for
disconnection
Fault found:
Repair, and
perform system
self-check.
No fault found:
replace EHCU.
Go to
Step 6
Repair.
Go to
Step 6
4Is stop light fuse normal?
Go to Step 5
Replace.
Go to
Step 6
5Is brake SW normal?Abnormal
harness in stop
light circuit.
Repair the
harness.
Go to
Step 6
Replace.
Go to
Step 6
61. Reconnect all components, ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 6

5A±45
BRAKE CONTROL SYSTEM
Chart B-16 Rear Dump Solenoid Coil Failure (DTC 46 (Flash out) / C0252, C0254 (Serial
communications))
StepActionYe sNo
1Was the ªEHCU Connector Pin±out Checksº performed?
Go to Step 2
Go to ªEHCU
Connector
Pin±out Checks.º
21. Turn the key switch to off.
2. Disconnect the 2±way EHCU connector (C±5) from the
EHCU.
3. Inspect the connector for damage or corrosion.
Is the connector free from damage or corrosion?
Go to Step 3
Repair the
connector.
Repeat the ªBasic
Diagnostic Flow
Chart.º
31. Replace the Coil Integrated Module.
2. Reconnect all components, ensure all components are
properly mounted.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 3
Chart B-17 FL Speed Sensor Open or Shorted (DTC 51 (Flash out) / C0225 (Serial
communications))
StepActionYe sNo
11. Turn the key off.
2. Disconnect coil integrated module connector.
3. Measure the resistance between coil integrated module
connector (C-6) terminals 2 and 10.
Is the resistance between 2.0k and 2.8k ohms?Check for faults
in harness
between speed
sensor and coil
integrated
module.
Fault found:
Repair, and
perform system
self-check.
No fault found:
Replace coil
integrated
module.
Go to
Step 3Go to Step 2
2Measure the FL speed sensor resistance at the sensor connector.
Is the resistance between 2.0k and 2.8k ohms?Repair harness
abnormality
between sensors
and coil
integrated
module.
Go to
Step 3
Replace sensor.
Go to
Step 3
31. Reconnect all components, ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 3

5A±46BRAKE CONTROL SYSTEM
Chart B-18 FR Speed Sensor Open or Shorted (DTC 52 (Flash out) / C0221 (Serial
communications))
StepActionYe sNo
11. Turn the key off.
2. Disconnect coil integrated module connector.
3. Measure the resistance between coil integrated module
connector (C-6) terminals 3 and 11.
Is the resistance between 2.0k and 2.8k ohms?Check for faults
in harness
between speed
sensor and coil
integrated
module.
Fault found:
Repair, and
perform system
self-check.
No fault found:
Replace coil
integrated
module.
Go to
Step 3Go to Step 2
2Measure the FR speed sensor resistance at the sensor
connector.
Is the resistance between 2.0k and 2.8k ohms?Repair harness
abnormality
between sensors
and coil
integrated
module.
Go to
Step 3
Replace sensor.
Go to
Step 3
31. Reconnect all components, ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chartº
Go to Step 3