Isuzu KB P190. Manual - part 158

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. 

Was 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. 

Was 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; 2WD Model or 4WD Model) 

Is the action complete? 

- 

Verify repair 

- 

 

 

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 

 

 

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~100Ω) 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. 

 

 

 

 

RTW75AMF000701 

Connector Pin-outs 

  ･Front Wheel Speed Sensor 

1 (+) 

(+12V) 

2 (-) 

(signal) 

  ･Rear Wheel 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%) 

 

 

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 4WD control system function normal? 

- 

2-4WD Repair 

or Go to Step 

7 

Repair or 

replace 2-

4WD 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