Isuzu N-Series. Service manual - part 289

HSA (HILL START AID) 5A5-35

15

Repair or replace the stop lamp switch.

Is the repair completed?

—

Go to Step15

Go to Step15

16

Connect the connector of the stop lamp
switch. Measure the battery voltage between
the HSA control unit connector terminal 19 “B-
285” and the body ground (with connector dis-
connected) with the brake pedal depressed. Is
the measurement completed?

20V or more

Go to Step18

Go to Step19

17

Repair the open circuit between the fuse “F-5”
and 1 “B-66” (stop lamp switch).

Is the repair completed?

—

Go to Step18

Go to Step17

18

Is the continuity (resistance) of neutral switch
normal?

—

Go to Step20

Go to Step21

19

Repair the open circuit between 2 “B-66” and
19 “B-285”.

Is the repair completed?

—

Go to Step20

Go to Step19

20

Measure the battery voltage between the neu-
tral switch connector terminal 2 “J-50” and the
body ground (with the connector discon-
nected). Is the measurement completed?

20V or more

Go to Step22

Go to Step23

21

Repair or replace the neutral switch.

Is the repair completed?

—

Go to Step22

Go to Step21

22

Connect the connector “J-50” of the neutral
switch.

Measure the battery voltage between the HSA
control unit connector terminal 18 “B-285” and
the body ground (with connector discon-
nected) with the gear in neutral. Is the mea-
surement completed?

20V or more 

with gear in 

neutral, 0V 

with gear 
except in 

neutral

Go to Step24

Go to Step25

23

Repair the open circuit between the fuse “F-
28” and 2 “J-50”.

Is the repair completed?

—

Go to Step24

Go to Step23

24

Measure the voltage between the HSA control
unit connector terminal 10 “B-285” and the
body ground (connector disconnected) with
engine running. Is the measurement com-
pleted?

Approx. 24 V

Go to Step26

Go to Step27

25

Repair the open circuit between 1 “J-50” and
18 “B-285”.

Is the repair completed?

—

Go to Step26

Go to Step25

26

Replace the HSA control unit.

Is the repair completed?

—

Go to Step28

Go to Step29

27

Repair the open circuit between the AC gen-
erator “L” terminal and 10 “B-285”.

Is the repair completed?

—

Go to Step30

Go to Step27

28

Replace the HSA control unit.

Is the repair completed?

—

Go to Step30

Go to Step28

Step

Action

Value

YES

NO

5A5-36 HSA (HILL START AID)

29

Repair or replace the parking brake switch.

Is the repair completed?

—

Go to Step30

Go to Step29

30

After HSA repair, make sure no trouble is
found during self-diagnosis.

Is this step completed?

—

—

Go to Step30

Step

Action

Value

YES

NO

HSA (HILL START AID) 5A5-37

0.5BR

0.3BR/W

0.3W/B

0.5B

30

12

PARKING

BRAKE

HSA

HSA CONTROL UNIT

B-51

18

5

B-52

2

B-285

B-51

B-7

B-285

HEADLIGHT BRACKET (LH)

J-9

FRAME

PARKING
BRAKE
SWITCH

12

2

0.3W/V

0.3W/V

3

4

10

3

0.5W/B

0.3W/B

0.5W/B

0.5W/R

0.5B

0.5W/B

WITH
HBB

W/O
HBB

0.3W/R

B-285

8

H-5

H-5

RELAY ;
BUZZER

SHORT CONNECTOR

X-33

9

7

X-33

8

X-33

H-12

J-128

J-128

4

3

2

J-128

1

J-128

N-6

1

HBB
LEVEL
SWITCH

DIODE
BOX

18

B-285

0.3B/L

0.5B/Y

NEUTRAL SWITCH

0.5B/L

37

F-28

ECM

J-50

H-5

J-50

2

1

FUSE

2B

14

B-285

0.5B/O

19

B-285

0.5G

0.5G/Y

STOP LAMP SWITCH

B-66

B-66

1

2

F-5

10A

F-17 10A

3B

METER

N5A3028E

5A5-38 HSA (HILL START AID)

Symptom: HSA Does not Release Though the HSA Off Switch Is Depressed

Step

Action

Value

YES

NO

1

Is the continuity (resistance) of the HSA off
switch normal?

—

Go to Step2

Go to Step3

2

Replace the HSA valve.

Is the repair completed?

—

Go to Step4

Go to Step2

3

Replace the HSA off switch.

Is the repair completed?

—

Go to Step4

Go to Step3

4

After HSA repair, make sure no trouble is
found during self-diagnosis.

Is this step completed?

—

—

Go to Step4