Isuzu N-Series. Service manual - part 249

ANTI-LOCK BRAKE SYSTEM (ABS) 5A4-61

ON-VEHICLE SERVICE

Electronic Hydraulic Control Unit (EHCU)

Removal

1. Disconnect battery ground cable.
2. Disconnect brake pipes.
3. Remove EHCU bracket fix bolts & nut.
4. Remove EHCU bracket.
5. Remove EHCU.

Installation

To install, follow the removal steps in the reverse order,
noting the following points.

Notice:

• If welding work is to be performed on the vehicle

using an electric arc welder, the EHCU should be
removed from the vehicle before the welding oper-
ation begins.

• Do not put a radio equipment etc, that emits strong

radio wave near the EHCU.

• Do not wet the control unit. If wetted, wipe off water

immediately and dry it fully.

• Never loosen any screw on the control unit.
• Do not paint the control unit.
• Prevent possible electrostatic discharge damage.
• Do not touch the control unit pin type terminal with

a metallic tip of a screwdriver or tester.

• Do not apply voltage to the terminal.

Methods of Matching and Taking Off Connec-
tors

Before Matching

Legend

1. Brake Pipe
2. EHCU Bracket Fix Bolt & Nut
3. EHCU Bracket
4. Harness Connector
5. EHCU

1

4

5

3

2

N5A1040E

Legend

1. Master Cylinder (front)
2. Master Cylinder (rear)
3. Rear Right Wheel Cylinder
4. Rear Left Wheel Cylinder
5. Front Right Wheel Cylinder
6. Front Left Wheel Cylinder

N5A1041E

N5A1042E

5A4-62 ANTI-LOCK BRAKE SYSTEM (ABS)

Semi Matching
Wire harness side connector should be inserted to
equipment side, then lever folds up about 30

°.

Notice:
Check the lever folding up.

Matching
Turn the lever to direction A and fix the lever lock to the
housing.

Finished Matching
On a vehicle in which the harness is clamped onto the
EHCU bracket, clamp the harness after matching the
connectors.

Notice:
Check the lever lock is fixed to housing certainly. The le-
ver or housing can be broken by turned to direction A
without the lever folding up (30

°).

Condition of Matching
On a vehicle in which the harness is clamped onto the
EHCU bracket, loosen the before taking off the connec-
tors.

N5A1043E

N5A1044E

N5A1045E

N5A1046E

ANTI-LOCK BRAKE SYSTEM (ABS) 5A4-63

Release of Lock
Push lever lock down until the condition it can be re-
leased.

Notice:
Check division A can be released.

Taking Off
Turn the lever to direction B.
When you feel the lever heavy in your hand (after turn-
ing about 40 degrees), turn the lever in the direction of
C.
The lever will not turn and the connector may fail if force
is applied in the direction of D.

Notice:
The lockarm can be broken by being turned to direction
B in case of incomplete locking.

Check the lever is turned certainly and take connector
off to direction E.
Finished Taking Off

N5A1047E

N5A1048E

N5A1049E

N5A1050E

5A4-64 ANTI-LOCK BRAKE SYSTEM (ABS)

Front Speed Sensor

Components

Removal

1. Remove speed sensor connector.
2. Remove sensor cable fixing bolts and/or nut.
3. Remove the speed sensor fixing bolt.
4. Remove speed sensor.

Inspection and Repair

1. Check the speed sensor pole piece for presence of

foreign materials; remove any dirt, etc.

2. Check the pole piece for damage; replace speed

sensor if necessary.

3. Check the speed sensor cable for short or open cir-

cuit, and replace with a new one if necessary.
To check for cable short or open, bend or stretch
the cable while checking for continuity.

Installation

1. Install speed sensor and take care not to hit the

speed sensor pole piece during installation.

2. Install speed sensor fixing bolt and tighten the fix-

ing bolt to the specified torque.

Tighten:
Bolt to 22 N

⋅m (2.2 kg⋅m/16 lb⋅ft)

3. Install speed sensor cable fixing bolts and tighten

the fixing bolt to the specified torque.

Tighten:
Bolts (2) to 22 N

⋅m (2.2 kg⋅m/16 lb⋅ft)

Bolts (3) to 45 N

⋅m (4.6 kg⋅m/33 lb⋅ft)

Nut (3) to 15 N

⋅m (1.5 kg⋅m/11 lb⋅ft)

Notice:
Confirm that a white or yellow line marked on the cable
is not twisted when connecting the speed sensor cable.

Legend

1. Speed Sensor Connector

4. Sensor Fixing Bolt

2. Sensor Cable Fixing Bolt

5. Speed Sensor

3. Sensor Cable Fixing Bolt (Front Disc Brake 

model)
Sensor Cable Fixing Nut (Front Drum Brake 
model)

6. Front

N5A1051E