2007 ISUZU KB P190 brake

5A-38 BRAKE CONTROL SYSTEM
Basic Diagnostic Flow Chart



RTW 75ALF000201
Step Action Value(s) Yes No
1 1. Ignition “ON”, engine “OFF”.
2. Observe the ABS warning lamp. Note: If the starter switch is turned ON, the ABS
warning lamp will turn on and then turn off after 3
seconds.
Is the ABS warning lamp “ON”? - Go to Step 2 Go to “No
ABS warning lamp”
2 1. Ignition “OFF”.
2. Install Tech 2.
3. Ignition “ON”.
4. Attempt to display ABS data with the Tech 2. Does the Tech 2 display ABS data? - Go to Step 5 Go to Step 3

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ISUZU KB P190 2007

BRAKE CONTROL SYSTEM 5A-39
Step Action Value(s) Yes No
3 1. Ignition “OFF”, disconnect the EHCU.
2. Check the DLC (Data Link Connector) circuit for an open, short to ground, or short to voltage.
Also, check the DLC ignition feed circuit for an open
or short to ground and the DLC ground circuit for an
open.
3. If a problem is found, repair as necessary. W as a problem found? - Go to Step 2 Go to Step 4
4 1. Check the EHCU circuit for an open, short to
ground, or short to voltage. Also, check the EHCU
ignition feed circuit for an open or short to ground
and the EHCU ground circuit for an open.
2. If a problem is found, repair as necessary. W as a problem found? - Go to Step 2 Go to Step 11
5 Select “Display DTCs” with the Tech 2.
Are any DTCs stored? - Go to Step 6 Go to Step 10
6 Review and record for Tech 2 Failure Records data
and DTCs.
Is the action complete? - Go to Step 7 -
7 The DTC is then stored. Is this DTC C0271 stored?
- Go to
applicable
DTC table
after Go to step 8 Go to Step 8
8 Clear the DTCs by “Clear the Information“ with Tech 2.
Did the DTCs clear? - Go to Step 9 -
9 Select “Display DTCs” with the Tech 2. Are any DTCs stored? - Go to
applicable
DTC table Go to Step 10
10 Review and record for Tech 2 data.
Is the action complete?
- Go to
Symptom
Diagnosis and Go to Basic Inspection
Procedure -
11 Replace the EHCU.
Note: Check the EHCU type for specification, when
the EHCU is replaced.
(Specification; 2W D Model or 4W D Model)
Is the action complete? - Verify repair -



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ISUZU KB P190 2007

5A-40 BRAKE CONTROL SYSTEM
Basic Inspection Procedure
1. Basic Inspection of Service Brake
Step Action
Value(s) Yes No
1 Is the fluid level normal?
- Go to Step 2 Replenish with
fluid
Go to Step 2
2 Does fluid leak? - Repair
Go to Step 3 Go to Step 3
3 Is the booster function normal? - Go to Step 4 Repair
Go to Step 4
4 Is the pad and rotor normal? - Go to Step 5 Repair
Go to Step 5
5 Reconnect all components. Ensure all components are properly mounted.
Is this step finished? - Finished Go to Step 5

2. Ground Inspection
Step Action
Value(s) Yes No
1 Are ABS related ground points normal?
- Go to Step 2 Repair
Go to Step 2
2 Reconnect all components. Ensure all component are properly mounted.
Is this step finished? - Finished Go to Step 2



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ISUZU KB P190 2007

BRAKE CONTROL SYSTEM 5A-41
Wheel Speed Sensor Inspection Procedure
Procedure
1.Ignition "OFF".
2.Disconnect each of the wheel speed sensors.
3.Connect the resistance (50 Ω~100 Ω) as follows.
4.Check the voltage at sensor harness connector.
Note: Voltage measurement is performed in the phase
where the wheel speed sensor is installed in vehicles.

RTW 75AMF000701
Connector Pin-outs
･Front W heel Speed Sensor
1 (+) (+12V)
2 (-) (signal)
･Rear W heel Speed Sensor
1 LH (+) (+12V)
2 LH (-) (signal)
3 RH (+)(+12V)
4 RH (-) (signal)






Output Value
High State 0.7~1.4V (±30%)
Low State 0.4~0.7V (±30%)


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ISUZU KB P190 2007

5A-42 BRAKE CONTROL SYSTEM
Symptom Diagnosis
The symptoms that cannot be indicated by warning
lamp can be divided into the following six categories:
1. ABS works frequently but vehicle does not decelerate.
2. Uneven braking occurs while ABS works.
3. The wheels are locked.

4. Brake pedal feel is abnormal.
5. Braking sound (from EHCU) is heard while not braking.
6. No ABS warning lamp
These are all attributable to problems which cannot be
detected by EHCU self-diagnosis. Use the customer
complaint and a test to determine which symptom is
present.
ABS Works Frequently But Vehicle Does Not Decelerate

Step Action Value(s) Yes No
1 Is braking force distribution normal between front and
rear of vehicle?
- Go to Step 2 Repair brake
parts.
Go to Step 7
2 Are axle parts installed normally?
- Go to Step 3 Repair axle
parts.
Go to Step 7
3 Is there play in each or any wheel speed sensor?
- Repair wheel
speed sensor.
Go to Step 7 Go to Step 4
4 Is there damage, or powered iron sticking to each or any wheel speed sensor/sensor rotor?
- Replace
wheel speed sensor or
sensor rotor.
Go to Step 7 Go to Step 5
5 Is the speed sensor of each wheel output normal?
- Go to Step 6 Replace
wheel speed sensor or repair
harness.
Go to Step 7
6 Is the 4W D control system function normal?
- 2-4W D Repair
or Go to Step 7 Repair or
replace 2-
4W D control System.
Go to Step 7
7 Reconnect all components, ensure all components are properly mounted.
Is this step finished? - Repeat the
“Basic
diagnostic
flow chart” Go to Step 7



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ISUZU KB P190 2007

BRAKE CONTROL SYSTEM 5A-43
Uneven Braking Occurs While ABS Works

Step Action Value(s) Yes No
1 Is there play in each or any sensor?
- Repair.
Go to Step 5 Go to Step 2
2 Damage or powdered iron sticking to each or any
sensor/sensor rotor? - Repair.
Go to Step 5 Go to Step 3
3 Is the output normal for each sensor?
- Go to Step 4 Replace
sensor or repair
harness.
Go to Step 5
4 Is brake pipe connecting order correct? Note: Check the EHCU type for specification, when
the EHCU is replaced.
(Specification; 2W D Model or 4W D Model) - Replace
EHCU.
Go to Step 5 Reconnect
brake pipe correctly.
Go to Step 5
5 Reconnect all components, ensure all components are properly mounted.
Is this step finished? - Repeat the
“Basic
diagnostic
flow chart” Go to Step 5

The Wheels Are Locked

Step Action Value(s) Yes No
1 Is ABS working?
- Go to Step 2 Go to Step 4
2 Is vehicle speed under 5 km/h? - Go to Step 3 Normal.
3 Is the output for each normal?
- Go to Step 4 Replace
sensor or repair
harness.
Go to Step 6
4 Is 2-4W D system function normal?
- Go to Step 5 Replace 2-
4W D control
unit or repair harness.
Go to Step 6
5 Is EHCU grounded properly? Note: Check the EHCU type for specification, when
the EHCU is replaced.
(Specification; 2W D Model or 4W D Model) - Replace
EHCU.
Go to Step 6 Repair.
Go to Step 6
6 Reconnect all components, ensure all components are properly mounted.
Is this step finished? - Repeat the
“Basic
diagnostic
flow chart” Go to Step 6


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ISUZU KB P190 2007

5A-44 BRAKE CONTROL SYSTEM
Brake Pedal Feed Is Abnormal

Step Action Value(s) Yes No
1 Is the stop light actuated when the brake pedal is
depressed? - Go to Step 2 Go to Step 3
2 1. Turn the ignition switch off.
2. Disconnect EHCU connector. Is the check voltage for EHCU connector terminals
when brake pedal is depressed than battery voltage? - Go to Step 4 Harness NG
between stop light SW and EHCU.
Go to Step 6
3 Is stop light fuse normal?
- Go to Step 5 Replace stop
light fuse.
Go to Step 6
4 Is the check continuity between EHCU connector to body grounded?
- Go to Step 6 Repair body
grounded harness.
Go to Step 6
5 Is stop light switch operation normal?
- Repair stop
light harness.
Go to Step 6 Replace stop
light switch.
Go to Step 6
6 Reconnect all components, ensure all components are properly mounted.
Is this step finished? - Repeat the
“Basic
diagnostic
flow chart” Go to Step 6


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ISUZU KB P190 2007

BRAKE CONTROL SYSTEM 5A-45
Braking Sound (From EHCU) Is Heard While Not Braking

Step Action Value(s) Yes No
1 Is this the first vehicle start after engine start?
- It is self
checking sound
Normal. Go to Step 2
2 Is vehicle speed at 15 km/h or 30 km/h?
- It is self
checking sound
Normal. Go to Step 3
3 Check for the following condition: • At the time of shift down or clutch operation.
• At the time of low road friction drive (ice or snow on 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. Did it occur under any of the conditions above? - ABS may
sometimes be
actuated even when brake pedal is not applied. Go to Step 4
4 Is there play in each or any sensor/wheel speed sensor rotor? - Repair.
Go to Step 7 Go to Step 5
5 Damage or powdered iron sticking to each or any sensor/wheel speed sensor rotor? - Repair.
Go to Step 7 Go to Step 6
6 Is each sensor normal? Note: Check the EHCU type for specification, the
EHCU is replaced.
(Specification; 2W D or 4W D Model)

- Check
harness/
connector for suspected
disconnection
If no
disconnection is found,
replace EHCU
Go to Step 7 Repair.
Go to Step 7
7 Reconnect all components, ensure all components are properly mounted.
Is this step finished? - Repeat the
“Basic
diagnostic
flow chart” Go to Step 7


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ISUZU KB P190 2007