Isuzu N-Series. Service manual — part 246
ANTI-LOCK BRAKE SYSTEM (ABS) 5A4-49
Chart 12 (DTC54/C0254) RR Speed Sensor Circuit Abnormality
Step
Action
Value(s)
YES
NO
1
1. Turn the key off.
2. Disconnect EHCU connector J-177 and
RL speed sensor connector J-148 (J-78).
3. Check the continuity between connector
J-177 terminal 12 and sensor connector
J-148 (J-78) terminal 1 (3).
Is there continuity?
—
2
Check the continuity between connector J-177
terminal 12 and connector J-177 terminal 1.
Is there continuity?
—
3
Check the continuity between connector J-177
terminal 21 and sensor connector J-148 (J-78)
terminal 2 (4).
Is there continuity?
—
4
Check the continuity between connector J-177
terminal 21 and connector J-177 terminal 1.
Is there continuity?
—
5
1. Connect the connector J-177 with EHCU.
2. Turn the key on.
3. Using DVM, measure the voltage be-
tween connector J-148 (J-78) terminal 2
(4) (vehicle side) and ground.
Does the DVM display a voltage within the
specified value?
9 — 16 V
6
Check the RL sensor output. (Refer to Chart
C-1-4)
Does the DTC repeat?
—
7
Repair open circuit, poor connection and/or
short circuit between the EHCU connectors
and speed sensor connectors.
Is this step complete?
—
—
8
Replace EHCU.
Is this step complete?
—
—
9
1. Reconnect all components, ensure all
components are properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
—
Go to “Basic diag-
nostic flow chart”.
—
5A4-50 ANTI-LOCK BRAKE SYSTEM (ABS)
Chart 13 (DTC61/C0261) Abnormal FL Speed Sensor Signal
Step
Action
Value(s)
YES
NO
1
Have the vehicle been jacked up?
Have two or three wheels been turned on the
brake tester intentionally?
—
Be careful that the
system may fail if
two or three
wheels are turned
forcibly.
The flow is now
complete.
Repair tires.
2
Are tire pressures, sizes and wear normal?
—
Repair tires.
3
Is there play in the FL wheel bearing?
—
4
Is there play in the FL speed sensor/sensor
rotor?
—
5
Is there powdered iron sticking to FL speed
sensor/sensor rotor?
—
6
Check the FL speed sensor. (Refer to Chart C-
1-1 or TC-1)
Is the FL sensor output normal?
—
7
Is there a broken tooth or indentation in the
sensor rotor?
—
8
Using DVM, measure the resistance between
J-177 EHCU connector terminal 33 and
ground.
Does the DVM display a resistance within the
specified value?
1000 k ohms
or more
9
1. Clear diagnostic trouble code.
2. Test drive and perform system self-check.
Does the DTC repeat?
—
10
Is there damage or indentation in the speed
sensor?
—
11
1. Disconnect FL sensor connector.
2. Using DVM, measure the resistance be-
tween J-75 sensor connector terminal 2
and ground.
Does the DVM display a resistance within the
specified value?
1000 k ohms
or more
12
Adjust wheel bearing preload.
Is action complete?
—
—
13
Repair or replace speed sensor/sensor rotor.
Is action complete?
—
—
14
Repair speed sensor/sensor rotor.
Is action complete?
—
—
15
Replace sensor rotor.
Is action complete?
—
—
ANTI-LOCK BRAKE SYSTEM (ABS) 5A4-51
Chart 14 (DTC62/C0262) Abnormal FR Speed Sensor Signal
16
Replace FL speed sensor.
Is action complete?
—
—
17
Check the FL speed sensor circuit. Refer to
Chart 9.
Is action complete?
—
Verify repair
—
18
Check for a poor connection and an open cir-
cuit on the harness between EHCU and sen-
sor connectors.
Refer to “Note on Intermittents” described in
earlier this section.
Is action complete?
—
—
19
1. Locate open circuit, poor connection or
short circuit on the harness between
EHCU and sensor connectors.
2. Repair the harness.
Is action complete?
—
20
Replace EHCU.
Is action complete?
—
—
21
1. Reconnect all components, ensure all
components are properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
—
Go to “Basic diag-
nostic flow chart”.
—
Step
Action
Value(s)
YES
NO
1
Have the vehicle been jacked up?
Have two or three wheels been turned on the
brake tester intentionally?
—
Be careful that the
system may fail if
two or three
wheels are turned
forcibly.
The flow is now
complete.
Repair tires.
2
Are tire pressures, sizes and wear normal?
—
Repair tires.
3
Is there play in the FR wheel bearing?
—
4
Is there play in the FR speed sensor/sensor
rotor?
—
5
Is there powdered iron sticking to FR speed
sensor/sensor rotor?
—
6
Check the FR speed sensor. (Refer to Chart
C-1-2 or TC-1)
Is the FR sensor output normal?
—
7
Is there a broken tooth or indentation in the
sensor rotor?
—
Step
Action
Value(s)
YES
NO
5A4-52 ANTI-LOCK BRAKE SYSTEM (ABS)
8
Using DVM, measure the resistance between
J-177 EHCU connector terminal 11 and
ground.
Does the DVM display a resistance within the
specified value?
1000 k ohms
or more
9
1. Clear diagnostic trouble code.
2. Test drive and perform system self-check.
Does the DTC repeat?
—
10
Is there damage or indentation in the speed
sensor?
—
11
1. Disconnect FR sensor connector.
2. Using DVM, measure the resistance be-
tween J-74 sensor connector terminal 2
and ground.
Does the DVM display a resistance within the
specified value?
1000 k ohms
or more
12
Adjust wheel bearing preload.
Is action complete?
—
—
13
Repair or replace speed sensor/sensor rotor.
Is action complete?
—
—
14
Repair speed sensor/sensor rotor.
Is action complete?
—
—
15
Replace sensor rotor.
Is action complete?
—
—
16
Replace FR speed sensor.
Is action complete?
—
—
17
Check the FR speed sensor circuit. Refer to
Chart 10.
Is action complete?
—
Verify repair
—
18
Check for a poor connection and an open cir-
cuit on the harness between EHCU and sen-
sor connectors.
Refer to “Note on Intermittents” described in
earlier this section.
Is action complete?
—
—
19
1. Locate open circuit, poor connection or
short circuit on the harness between
EHCU and sensor connectors.
2. Repair the harness.
Is action complete?
—
20
Replace EHCU.
Is action complete?
—
—
Step
Action
Value(s)
YES
NO
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