Isuzu N-Series. Service manual - part 288

Replace the HSA valve.

Is the repair completed?

—

Is the battery voltage applied between the
HSA valve connector terminals 2 “J-155”, 4 “J-
155” and the body ground (with connector dis-
connected)?

20 V or more

Repair the open circuit of the circuit that has
resistance of 5

Ω or more.

Is the repair completed?

—

Replace the HSA control unit.

Is the repair completed?

—

Repair the open circuit of the circuit that has
resistance of less than 20V.

Is the repair completed?

—

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

Is this step completed?

—

5A5-32 HSA (HILL START AID)

N5A3027E

HSA (HILL START AID) 5A5-33

List of Trouble Phenomenon

For the troubles which are not appeared as trouble
code, interview the customer and the test run the vehicle

to check for trouble symptom, and perform the diagnosis
according the symptom.

Possible cause

Trouble
symptom

Door

switch

Park-

ing

brake

switch

Clutch

fluid

pres-

sure

switch

HSA

reset

switch

HSA

valve,

pipe

ACG

HSA

lamp

(includ

ing

meter)

HSA

off

switch

HSA

adjust
switch

Speed

sensor

Neu-

tral

switch

Stop

lamp

switch

Clutch

sensor

Back-

lamp

switch

Diode

box

Action to
be taken

HSA does not
operate.

❍

Refer to
the trouble
symptom.

HSA does not
release though
the HSA off
switch is
depressed.

❍

Refer to
the trouble
symptom.

HSA does not
release though
the vehicle is
operated to
start. (HSA indi-
cator lamp
remains ON.)

❍

Refer to
the trouble
symptom.

HSA does not
release though
the parking
brake is
applied.

❍

Refer to
the trouble
symptom.

HSA indicator
lamp does not
come on. (HSA
does not oper-
ate.)

❍

Refer to
the trouble
symptom.

HSA indicator
lamp does not
come on. (HSA
does operate.)

❍

Refer to
the trouble
symptom.

HSA indicator
lamp does not
go off. (HSA
released.)

❍

Refer to
the trouble
symptom.

Buzzer does
not sound
though the door
is opened while
HSA operating.

❍

Refer to
the trouble
symptom.

HSA indicator
lamp blinks
abnormally and
does not out-
put the trouble
cord during
self-diagnosis.

❍

Refer to
the trouble
symptom.

Buzzer beeps
continuously
during self-
diagnosis (trou-
ble code out-
put impossible)

❍

Refer to
the trouble
symptom.

5A5-34 HSA (HILL START AID)

Symptom: HSA Does not Operate

Step

Action

Value

YES

Does the HSA indicator lamp not illuminate?

—

Go to Step2

Go to Step3

Is the fuse “F-17” normal?

—

Go to Step4

Check the HSA valve and the pipe, and repair
or replace.

Is the repair completed?

—

Go to Step3

Measure the battery voltage between the HSA
control unit connector terminal 14 “B-285” and
the body ground (with connector discon-
nected). Is the measurement completed?

20 V or more

Repair the short circuit in the circuit and the
parts (clutch fluid pressure switch, HSA valve,
etc.) connected to the fuse “F-17”, and then
replace the fuse.

Is the repair completed?

—

Measure the resistance between the HSA
control unit connector terminal 30 “B-285” and
the body ground (with connector discon-
nected). Is the measurement completed?

Less than 5

Ω

Repair the open circuit between the fuse “F-
17” and 14 “B-285”.

Is the repair completed?

—

Measure the battery voltage between the HSA
control unit connector terminal 2 “B-285” and
the body ground (with connector discon-
nected) with the parking brake not applied. Is
the measurement completed?

20 V or more

Go to Step11

Repair the open circuit or improper grounding
between 30 “B-285” and the ground terminal
“B-7” (in front of the frame LH) (with the con-
nector disconnected).

Is the repair completed?

—