Isuzu N-Series. 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?

—

Go to Step 2

Go to Step 7

2

Check the continuity between connector J-177
terminal 12 and connector J-177 terminal 1.

Is there continuity?

—

Go to Step 7

Go to Step 3

3

Check the continuity between connector J-177
terminal 21 and sensor connector J-148 (J-78)
terminal 2 (4).

Is there continuity?

—

Go to Step 4

Go to Step 7

4

Check the continuity between connector J-177
terminal 21 and connector J-177 terminal 1.

Is there continuity?

—

Go to Step 7

Go to Step 5

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

Go to Step 6

Go to Step 7

6

Check the RL sensor output. (Refer to Chart
C-1-4)

Does the DTC repeat?

—

Go to Step 8

Go to Step 9

7

Repair open circuit, poor connection and/or
short circuit between the EHCU connectors
and speed sensor connectors.

Is this step complete?

—

Go to Step 9

—

8

Replace EHCU.

Is this step complete?

—

Go to Step 9

—

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.

Go to Step 2

2

Are tire pressures, sizes and wear normal?

—

Go to Step 3

Repair tires.

Go to Step 2

3

Is there play in the FL wheel bearing?

—

Go to Step 12

Go to Step 4

4

Is there play in the FL speed sensor/sensor
rotor?

—

Go to Step 13

Go to Step 5

5

Is there powdered iron sticking to FL speed
sensor/sensor rotor?

—

Go to Step 14

Go to Step 6

6

Check the FL speed sensor. (Refer to Chart C-
1-1 or TC-1)

Is the FL sensor output normal?

—

Go to Step 7

Go to Step 10

7

Is there a broken tooth or indentation in the
sensor rotor?

—

Go to Step 15

Go to Step 8

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

Go to Step 9

Go to Step 11

9

1. Clear diagnostic trouble code.
2. Test drive and perform system self-check.

Does the DTC repeat?

—

Go to Step 20

Go to Step 18

10

Is there damage or indentation in the speed
sensor?

—

Go to Step 16

Go to Step 17

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

Go to Step 19

Go to Step 16

12

Adjust wheel bearing preload.

Is action complete?

—

Go to Step 21

—

13

Repair or replace speed sensor/sensor rotor.

Is action complete?

—

Go to Step 21

—

14

Repair speed sensor/sensor rotor.

Is action complete?

—

Go to Step 21

—

15

Replace sensor rotor.

Is action complete?

—

Go to Step 21

—

ANTI-LOCK BRAKE SYSTEM (ABS) 5A4-51

Chart 14 (DTC62/C0262) Abnormal FR Speed Sensor Signal

16

Replace FL speed sensor.

Is action complete?

—

Go to Step 21

—

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?

—

Go to Step 21

—

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?

—

Go to Step 21

Go to Step 21

20

Replace EHCU.

Is action complete?

—

Go to Step 21

—

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.

Go to Step 2

2

Are tire pressures, sizes and wear normal?

—

Go to Step 3

Repair tires.

Go to Step 2

3

Is there play in the FR wheel bearing?

—

Go to Step 12

Go to Step 4

4

Is there play in the FR speed sensor/sensor
rotor?

—

Go to Step 13

Go to Step 5

5

Is there powdered iron sticking to FR speed
sensor/sensor rotor?

—

Go to Step 14

Go to Step 6

6

Check the FR speed sensor. (Refer to Chart
C-1-2 or TC-1)

Is the FR sensor output normal?

—

Go to Step 7

Go to Step 10

7

Is there a broken tooth or indentation in the
sensor rotor?

—

Go to Step 15

Go to Step 8

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

Go to Step 9

Go to Step 11

9

1. Clear diagnostic trouble code.
2. Test drive and perform system self-check.

Does the DTC repeat?

—

Go to Step 20

Go to Step 18

10

Is there damage or indentation in the speed
sensor?

—

Go to Step 16

Go to Step 17

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

Go to Step 19

Go to Step 16

12

Adjust wheel bearing preload.

Is action complete?

—

Go to Step 21

—

13

Repair or replace speed sensor/sensor rotor.

Is action complete?

—

Go to Step 21

—

14

Repair speed sensor/sensor rotor.

Is action complete?

—

Go to Step 21

—

15

Replace sensor rotor.

Is action complete?

—

Go to Step 21

—

16

Replace FR speed sensor.

Is action complete?

—

Go to Step 21

—

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?

—

Go to Step 21

—

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?

—

Go to Step 21

Go to Step 21

20

Replace EHCU.

Is action complete?

—

Go to Step 21

—

Step

Action

Value(s)

YES

NO