DTC CHECK ISUZU KB P190 2007 Workshop Repair Manual

BRAKE CONTROL SYSTEM 5A-21
EHCU Side
Pin No. Pin Function
Wire Color Typical Value Note
20 Stop Light Switch RED Open: 0V
Close: Battery Voltage Close Condition:
Step on the Brake
Pedal
21 G Sensor Signal YEL/BLK 2.0~3.0V
(MAX 4.0V, MIN 1.0V) 4W D Only
It checks in a flat place
(0G: 2.5V)
DTC C0276, C0285
22 ABS W arning Lamp YEL More than 10V -
23 Not Used - - -
24 Transfer (2-4W D Control Unit) GRY Pulse Signal
(High 4.5V, Low 1.5V) 4W D Only
DTC C0282
25 Serial ORN/W HT- Short to GND:
Flash out DTCs
26 Not Used - - -


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ISUZU KB P190 2007

5A-24 BRAKE CONTROL SYSTEM
Computer System Service Precautions
The Anti-lock Brake System and Electronic Brake-force
Distribution interfaces directly with the Electronic
Hydraulic Control Unit (EHCU) which is a control
computer that is similar in some regards to the Engine
Control Module. These modules are designed to
withstand normal current draws associated with vehicle
operation. However, care must be taken to avoid
overloading any of the EHCU circuits. In testing for
opens or shorts, do not ground or apply voltage to any
of the circuits unless instructed to do so by the
appropriate diagnostic procedure. These circuits should
only be tested with a high impedance multimeter
5-8840-0366-0 or special tools as described in this
section. Power should never be removed or applied to
any control module with the ignition in the “ON” position.
Before removing or connecting battery cables, fuses or
connectors, always turn the ignition switch to the “OFF”
position.

General Service Precautions
The following are general precautions which should be
observed when servicing and diagnosing the Anti-lock
Brake System and/or other vehicle systems. Failure to
observe these precautions may result in Anti-lock Brake
System and Electronic Brake-force Distribution
damage.
• If welding work is to be performed on the vehicle using an electric arc welder, the EHCU and valve
block connectors should be disconnected before the
welding operation begins.
• The EHCU and valve block connectors should never be connected or disconnected with the
ignition “ON”.
Note:
• If only rear wheels are rotated using jacks or drum tester, the system will diagnose a speed sensor
malfunction and the “ABS and Brake” warning lamp
will illuminate. But actually no trouble exists. W hen
the DTC is not detected and the ABS and BRAKE
warning lamp is on, “How to erase code” is
performed and an ABS and BRAKE warning lamp
are off.
If the battery has been discharged
The engine may stall if the battery has been completely
discharged and the engine is started via jumper cables.
This is because the Anti-lock Brake System (ABS) and
Electronic Brake-force Distribution (EBD) System
requires a large quantity of electricity. In this case, wait
until the battery is recharged, or set the ABS and EBD
to a non-operative state by removing the fuse for the
ABS. After the battery has been recharged, stop the
engine and install the ABS fuse. Start the engine again,
and confirm that the ABS warning Lamp does not light.
Note on Intermittents
As with virtually any electronic system, it is difficult to
identify an intermittent failure. In such a case duplicating
the system malfunction during a test drive or a good
description of vehicle behavior from the customer may
be helpful in locating a “most likely” failed component or
circuit. The symptom diagnosis chart may also be
useful in isolating the failure. Most intermittent
problems are caused by faulty electrical connections or
wiring. W hen an intermittent failure is encountered,
check suspect circuits for:
• Suspected harness damage.
• Poor mating of connector halves or terminals not fully seated in the connector body (backed out).
• Improperly formed or damaged terminals.

Test Driving ABS Complaint Vehicles
If there has been an abnormality in the lighting pattern
of the “ABS” warning lamp, the fault can be located in
accordance with the “DIAGNOSIS BY “ABS” W ARNING
LAMP ILLUMINATION PATTERN”. Although such
problems can be detected by the driver as a vehicle
symptom, it is still necessary to perform a test drive
following the test procedure mentioned below, in order
to reproduce the symptom for problem diagnosis on a
symptom basis:
1. Start the engine and make sure that the “ABS” W /L
goes OFF. If the W /L remains ON, it means that
the Diagnostic Trouble Code (DTC) is stored.
Therefore, read the code and locate the fault.
Note: The DTC cannot be cleared if the vehicle speed
does not exceed about 10km/h (6mph) at DTC, even
though the repair operation is completed.
2. Start the vehicle and accelerate to about 30 km/h (19 mph) or more.
3. Slowly brake and stop the vehicle completely.
4. Then restart the vehicle and accelerate to about 40 km/h (25 mph) or more.
5. Brake at a time so as to actuate the ABS and stop the vehicle.
6. Be cautious of abnormality during the test. If the W /L is actuated while driving, read the DTC and
locate the fault.
7. If the abnormality is not reproduced by the test, make best efforts to reproduce the situation
reported by the customer.
8. If the abnormality has been detected, repair in accordance with the “SYMPTOM DIAGNOSIS”.
Note:
• Be sure to perform a test drive on a wide, even road
with light traffic.
• If an abnormality is detected, be sure to suspend the test and start trouble diagnosis at once.

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5A-28 BRAKE CONTROL SYSTEM
4. Check the EHCU part number. Press the "Confirm".





RTW 75ASH000501

5. Check a DTC is not detected. Press the "Confirm".




RTW 75ASH000601
6. According to indication of Tech 2 press the
"Confirm".





RTW 75ASH000701

7. According to indication of Tech 2 press the
"Confirm".




RTW 75ASH000801


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BRAKE CONTROL SYSTEM 5A-37
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
Display of DTC 23

B05R100001
After displaying DTC 12 three times, one DTC after
another is displayed. DTC is displayed in numeric
order.
C05L300017
The DTC 12 is displayed repeatedly.




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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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5A-48 BRAKE CONTROL SYSTEM
DTC C0221 (Flash Code 21) Front Right Wheel Speed Sensor Short Circuit or
Circuit Open



RTW 75AMF001301

Step Action Value(s) Yes No
1 W ere the steps of the “Basic Diagnostic Flow Chart”
performed?
- Go to Step 2 Go to Basic
Diagnostic
Flow Chart
2 1. Check for a poor connection at the front right wheel speed sensor harness connector.
2. Check installation condition for front right wheel speed sensor.
3. If a problem is found, repair as necessary. W as a problem found? - Verify repair Go to Step 3
3 1. Ignition “OFF”, disconnect the EHCU and front right
wheel speed sensor.
2. Check the circuit between EHCU and front right wheel speed sensor. (Circuit for an open, short to
ground, or short to voltage.)
3. If a problem is found, repair as necessary. W as a problem found? - Verify repair Go to Step 4

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BRAKE CONTROL SYSTEM 5A-49
Step Action
Value(s) Yes No
4 1. Replace front right wheel speed sensor.
2. Select “Display DTCs” with the Tech 2. Note: Perform the various tests (actuator test, test
run, brake test, etc.) then observe the DTC with a
Tech 2.
Are any DTCs stored? - Go to Step 5 Verify repair
5 Replace 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-50 BRAKE CONTROL SYSTEM
DTC C0222 (Flash Code 22) Front Right Wheel Speed Sensor Signal
Malfunction



RTW 75AMF001301

Step Action Value(s) Yes No
1 W ere the steps of the “Basic Diagnostic Flow Chart” performed?
- Go to Step 2 Go to Basic
Diagnostic
Flow Chart
2 1. Check the tire for the following conditions.
• Tire specification
• W ear of the outer surface
2. If a problem is found, repair as necessary. W as a problem found? - Verify repair Go to Step 3
3 Note:
This DTC is set when certain tire is rotated alone.

Has certain tire been rotated alone by performing for
lift-up or roller tester? - Verify repair Go to Step 4
4 Is the front right wheel bearing rattling?
- Go to Step 11 Go to Step 5
5 Is the front right wheel speed sensor or the sensor
rotor rattling? - Go to Step 12 Go to Step 6
6 Is iron powder attached to the front right wheel speed
sensor or the sensor rotor? - Go to Step 13 Go to Step 7

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BRAKE CONTROL SYSTEM 5A-51
Step Action Value(s) Yes No
7 Check the front right wheel speed sensor. Refer to
"W heel Speed Sensor Inspection procedure"
W as a problem found? - Go to Step 10 Go to Step 8
8 Does the sensor rotor have missing tooth or saw- toothed? - Go to Step 14 Go to Step 9
9 1. Clear the DTC.
2. Test run the vehicle, and check the DTC. Is the DTC displayed repeatedly? - Go to Step 18 Go to Step 17
10 Is the wheel speed sensor damaged or saw-toothed?
- Go to Step 15 Go to Step 16
11 Adjust the preload of the wheel bearing.
Is the action complete? - Verify repair -
12 Repair or replace the front right speed sensor or the
sensor rotor.
Is the action complete? - Verify repair -
13 Repair the front right speed sensor or the sensor rotor.
Is the action complete? - Verify repair -
14 Replace the sensor rotor. Is the action complete? - Verify repair -
15 Replace the front right wheel speed sensor.
Is the action complete? - Verify repair -
16 Repair or replace the front right speed sensor
circuits.
Is the action complete? - Verify repair -
17 Check the connection btween the EHCU and the front right wheel speed sensor and repair as
necessary Refer to "Note on Intermittents".
Is the action complete? - Verify repair -
18 Replace 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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5A-52 BRAKE CONTROL SYSTEM
DTC C0225 (Flash Code 25) Front Left Wheel Speed Sensor Short Circuit or
Circuit Open



RTW 75AMF001301

Step Action Value(s) Yes No
1 W ere the steps of the “Basic Diagnostic Flow Chart”
performed?
- Go to Step 2 Go to Basic
Diagnostic
Flow Chart
2 1. Check for a poor connection at the front left wheel speed sensor harness connector.
2. Check installation condition for front left wheel speed sensor.
3. If a problem is found, repair as necessary. W as a problem found? - Verify repair Go to Step 3
3 1. Ignition “OFF”, disconnect the EHCU and front left
wheel speed sensor.
2. Check the circuit between EHCU and front left wheel speed sensor. (Circuit for an open, short to
ground, or short to voltage.)
3. If a problem is found, repair as necessary. W as a problem found? - Verify repair Go to Step 4

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ISUZU KB P190 2007