Isuzu N-Series. Manual — part 238
ANTI-LOCK BRAKE SYSTEM (ABS) 5A4-17
ABS Relay
Test condition: Engine stops with the key turned to the
“ON” position. To be more specific, the test is conducted
with the brake pedal stepped on after stepping once and
releasing.
Make sure of the working sound of the ABS relay.
The circuit is normal if the working sound of the ABS re-
lay is made in accordance with Tech 2’s instruction.
ABS Motor
Test condition: Engine stops with the key turned to the
“ON” position. To be more specific, the test is conducted
with the brake pedal stepped on after stepping once and
releasing.
Make sure of the working sound of the ABS motor.
The circuit is normal if the working sound of the ABS mo-
tor is made in accordance with Tech 2’s instruction.
Exhaust Brake Cut Relay
Test condition: Engine stops with the key turned to the
“ON” position. To be more specific, the test is conducted
with the brake pedal stepped on after stepping once and
releasing.
Make sure of the working sound of the exhaust brake cut
relay.
The circuit is normal if the working sound of the exhaust
brake cut relay is made in accordance with Tech 2’s in-
struction.
Hold Valve Test
Purpose: The purpose of this test is to detect brake pipe
and valve line harness wire wrong connections and
valve trouble.
This test will help you confirm the result of your repair
service including the removal/reinstallation of brake
pipe, valve line harness and valve.
Actuator Test
F1:
F2:
F3:
Return Pump Relay Test
Front Left Solenoid Valve Test
Front Right Solenoid Valve Test
F4:
F5:
F6:
F7:
Rear Left Solenoid Valve Test
Rear Right Solenoid Valve Test
ABS Check Light Test
Exhaust Brake Cut Test
N5A1020E
Actuator Test
F0:
F2:
F3:
ABS Relay Test
Front Left Solenoid Valve Test
Front Right Solenoid Valve Test
Rear Left Solenoid Valve Test
Rear Right Solenoid Valve Test
ABS Check Light Test
Exhaust Brake Cut Test
F4:
F5:
F6:
F7:
N5A1021E
Actuator Test
F0:
F1:
F2:
F3:
ABS Relay Test
Return Pump Relay Test
Front Left Solenoid Valve Test
Front Right Solenoid Valve Test
Rear Left Solenoid Valve Test
Rear Right Solenoid Valve Test
ABS Check Light Test
F4:
F5:
F6:
N5A1022E
Actuator Test
F0:
F1:
F3:
ABS Relay Test
Return Pump Relay Test
Front Right Solenoid Valve Test
Rear Left Solenoid Valve Test
Rear Right Solenoid Valve Test
ABS Check Light Test
Exhaust Brake Cut Test
F4:
F5:
F6:
F7:
N5A1023E
5A4-18 ANTI-LOCK BRAKE SYSTEM (ABS)
Test conditions: The ignition key is the “ON” position
with the four wheels lifted up. The brake pedal is
stepped on, released and stepped on again with the
parking brake released.
Test procedure:
1. Connect Tech 2 with the vehicle, and select Spe-
cial Function from the menus.
2. Select a Hold Valve Menu from the Special Func-
tion Menus.
Select a ISO Solenoid from the Front Left Solenoid
Valve Test Function Menus.
3. Press the Hold Valve “ON” Soft Key with the brake
pedal stepped on.
4. Release the brake pedal.
5. Make sure that the Hold Valve “ON” aimed at by
Tech 2 and the wheel locked position are the
same. If different, check brake pipe, valve line har-
ness wiring and H/UNIT. Repair is needed if abnor-
mality is found.
6. Conduct Step 2 through Step 5 above on all the
four wheels.
Caution:
When conducting this test, please observe the following
cautions.
1. Do not start the engine without fail.
2. Lift up the vehicle at the level floor.
• Secure a clearance from the floor surface
enough to allow the lifted tire to rotate.
3. Maintain the lift up.
4. Wipe the floor surface to remove water and oil so
that the surface may become unslippery.
5. Do not load the vehicle.
• When lifting up the vehicle, be sure to observe
the lifting up points. Refer to vehicle lifting
points in Section 0A GENERAL INFORMA-
TION.
Release Valve Test
Purpose: The purpose of this test is to detect brake pipe
and valve line harness wire wrong connections and
valve trouble.
This test will help you confirm the result of your repair
service including the removal/reinstallation of brake
pipe, valve line harness and valve.
Test conditions: The ignition key is in the “ON” position
with the four wheels lifted up. The brake pedal is
stepped on, released and stepped on again with the
parking brake released.
Test procedure:
1. Connect Tech 2 with the vehicle, and select Spe-
cial Function from the menus.
2. Select a Release Valve Menu from the Special
Function Menus.
Actuator Test
F0:
F1:
F3:
ABS Relay Test
Return Pump Relay Test
Front Right Solenoid Valve Test
Rear Left Solenoid Valve Test
Rear Right Solenoid Valve Test
ABS Check Light Test
Exhaust Brake Cut Test
F4:
F5:
F6:
F7:
N5A1023E
Front Left Solenoid Valve Test
Dump Solenoid
N5A1024E
Actuator Test
F0:
F1:
F3:
ABS Relay Test
Return Pump Relay Test
Front Right Solenoid Valve Test
Rear Left Solenoid Valve Test
Rear Right Solenoid Valve Test
ABS Check Light Test
Exhaust Brake Cut Test
F4:
F5:
F6:
F7:
N5A1023E
ANTI-LOCK BRAKE SYSTEM (ABS) 5A4-19
Select a Dump Solenoid from the Front Left Solenoid
Valve Test Function Menus.
3. Press the Release Valve “ON” Soft Key with the
brake pedal stepped on.
4. Make sure that the Release Valve “ON” aimed at
by Tech 2 and the wheel released position are the
same. If different, check brake pipe, valve line har-
ness wiring and H/UNIT. Repair is needed if abnor-
mality is found.
5. Conduct Step 2 through Step 4 above on all the
four wheels.
Caution:
When conducting this test, please observe the following
cautions.
1. Do not start the engine without fail.
2. Lift up the vehicle at the level floor.
• Secure a clearance from the floor surface
enough to allow the lifted tire to rotate.
3. Maintain the lift up.
4. Wipe the floor surface to remove water and oil so
that the surface may become unslippery.
5. Do not load the vehicle.
• When lifting up the vehicle, be sure to observe
the lifting up points. Refer to vehicle lifting
points in Section 0A GENERAL INFORMA-
TION.
Actuator Test
F0:
F1:
F3:
ABS Relay Test
Return Pump Relay Test
Front Right Solenoid Valve Test
Rear Left Solenoid Valve Test
Rear Right Solenoid Valve Test
ABS Check Light Test
Exhaust Brake Cut Test
F4:
F5:
F6:
F7:
N5A1023E
Front Left Solenoid Valve Test
Iso Solenoid
N5A1027E
5A4-20 ANTI-LOCK BRAKE SYSTEM (ABS)
EHCU Connector Pin-out Checks
• Disconnect EHCU.
• Perform checks with high impedance digital multimeter 5-8840-0285-0 (J-39200) or equivalent.
No.
Circuit to be Tested
Key
Switch
Position
Multimeter
Scale/Range
Measure
between Pin
Nominal Value (24 V
Battery Vehicle)
Note
1
EHCU Power Circuit
OFF
VDC
3(+) — 1(
−)
0 — 0.3 V
ON
VDC
3(+) — 1(
−)
9.5 — 16.5 V
(16.5 — 34 V)
OFF
VDC
2(+) — 1(
−)
9.5 — 16.5 V
(16.5 — 34 V)
OFF
VDC
24(+) — 1(
−)
9.5 — 16.5 V
(16.5 — 34 V)
2
EHCU Ground Circuit
OFF
Ω
1(+) — GND
Less than 0.01
Ω
OFF
Ω
23(+) — GND
Less than 0.01
Ω
3
EXHIN Circuit
ON
VDC
7(+) — 1(
−)
9.5 — 16.5 V
(16.5 — 34 V)
Engine Run
4
EXHOUT Circuit
ON
VDC
8(+) — 1(
−)
9.5 — 16.5 V
(16.5 — 34 V)
OFF
VDC
8(+) — 1(
−)
0 — 0.3 V
5
Brake Switch Signal
Circuit
OFF
VDC
16(+) — 1(
−)
0 — 0.3 V
OFF
VDC
16(+) — 1(
−)
9.5 — 16.5 V
(16.5 — 34 V)
Apply Brake
Pedal
6
ABS W/L Circuit
ON
VDC
6(+) — 1(
−)
9.5 — 16.5V
(16.5 — 34 V)
OFF
VDC
6(+) — 1(
−)
0 — 0.3 V
7
FL Speed Sensor
OFF
k
Ω
10(+) — 11(
−)
1 — 2 k
Ω
OFF
k
Ω
10(+) — 1(
−)
More than 1000 k
Ω
OFF
VDC
10(+) — 11(
−)
More than 200 mV
Turn Wheel at
0.5 RPS
8
FR Speed Sensor
OFF
k
Ω
32(+) — 33(
−)
1 — 2 k
Ω
OFF
k
Ω
32(+) — 1(
−)
More than 1000 k
Ω
OFF
VDC
32(+) — 33(
−)
More than 200 mV
Turn Wheel at
0.5 RPS
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