2002 ISUZU AXIOM ABS

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±36BRAKE CONTROL SYSTEM
Diagnosis By ªABSº Warning Light
Illumination Pattern
In the event that there is abnormality in the ªABSº warning
light illumination pattern while the key is in the ON position
or if the warning light is actuated while driving, refer to the
flow chart below for the correct diagnostic procedure.
No.
ConditionªABSº Warning Light Illumination PatternDiagnostic
1Warning light is
actuated normallyNormal
2Warning light is not litWarning light lighting circuit
trouble"Go to Chart B-1
3Warning light remains
ONDiagnostic trouble codes are
stored.
Display diagnostic trouble
codes and diagnose on a
code basis according to the
flow charts.
4Warning light is
actuated while drivingDiagnostic trouble codes are
stored.
Display diagnostic trouble
codes and diagnose on a
code basis according to the
flow charts.
5Warning light goes at
12 km/h (8 mph) or
higher (After repairing
the faulty part)Even after repairing the
faulty part the warning light
(W/L) dose not go out if
vehicle is at a stop.
Turn the ignition switch to the
ON position and drive the
vehicle at 12 km/h (8 mph) or
higher to make sure that the
warning light goes out.

5A±37
BRAKE CONTROL SYSTEM
Diagnostic Trouble Codes (DTCs)
When the warning light in the meter remains ON, the
EHCU stores the fault identification and disables the
ABS.
How to display and erase DTCs:
NOTE:

DTCs can be displayed also by TECH 2. Use
ªDiagnostic Trouble Codesº mode.1. How to start DTC display:

Confirm that the vehicle has come to a complete
stop (with the wheels standing still) and that the
brake pedal is not depressed. (Unless these two
condition are satisfied, DTC display cannot be
started.)

With IGN OFF, connect #12 terminal with #4
terminal or # 5 terminal (GND) . Then turn IGN ON.
The DLC is located behind the driver side kick panel
350R200001

Keep #12 terminal connected with #4 terminal or # 5
terminal (GND) during DTC display. (If #12 terminal
is separated from #4 terminal or # 5 terminal (GND)
during display, display will stop.)
2. DTC display:

DTC is displayed by blinking warning light.

Double-digit display.

First, normal DTC 12 is displayed three times and
then any other DTCs are displayed three times. (If
no other DTCs have been stored, the display of DTC
12 will be repeated.)3. How to erase code:

Conduct brake switch ON/OFF operation 6 or more
times within 3 seconds of self-diagnosis startup.

The code cannot be erased if more than 3 seconds
have passed since self-diagnosis startup, or if
self-diagnosis has started with brake switched on
(brake pedaled).
B05RW005

5A±38BRAKE CONTROL SYSTEM
4. Notes

If the following should occur during Diagnostic
Trouble Code (DTC) display, the display will be
discontinued. After initial check, the status that is
under the control of ABS will be returned :
± The vehicle starts (The wheels turn) or the brake
pedal is depressed.

Up to 3 different codes can be stored.

If the ABS should turn OFF due to an intermittent
defect, the system will be restored at the next key
cycle, if the initial check finds no abnormality (when
IGN is switched from OFF to ON).
5. An example of DTC display
B05R100001
After displaying DTC 12 three times, one DTC after
another is displayed, starting with the most recent
one. (However, display is discontinued after about 5
minutes.)
B05R100002
The DTC 12 is displayed repeatedly. (display is
discontinued after about 5 minutes after)

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