Isuzu N-Series. Manual - part 286

HSA (HILL START AID) 5A5-23

DTC 19 Adjust Switch “FAST” or “SLOW” Remain ON

Step

Action

Value

YES

NO

1

Is the battery voltage applied between the
HSA adjust switch connector terminal 3 “B-
106” and the body ground (connector discon-
nected)?

20 V or more

Go to Step2

Go to Step3

2

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

—

Go to Step4

Go to Step5

3

Repair the open circuit between the fuse “F-
17” and 3 “B-106”.

Has the open circuit corrected?

—

Go to Step4

Go to Step3

4

Connect the connector of the HSA adjust
switch.

Measure the voltages between the HSA con-
trol unit connector terminals 15 “B-285”, 21
“B-285” and the body ground. Are the volt-
ages 20V or more with adjust switch operat-
ing, and 0V not operating (with the HSA
control unit connector disconnected)?

20V with 

switch oper-

ated 0V with 

not operated

Go to Step6

Go to Step7

5

Repair or replace the switch.

Is the repair completed?

—

Go to Step6

Go to Step5

6

Replace the HSA control unit.

Is the replacement completed?

—

Go to Step7

Go to Step6

7

Repair the open circuit between the HSA
adjust switch connector terminals and the
HSA control unit connector terminals 2 “B-
106” — 15 “B-285”, 1 “B-106” — 21 “B-285”.

Is the repair completed?

—

Go to Step8

Go to Step7

8

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

Is this step completed?

—

—

Go to Step8

5A5-24 HSA (HILL START AID)

N5A3023E

HSA (HILL START AID) 5A5-25

DTC 25 Vehicle Speed Sensor Output Voltage Fault

Step

Action

Value

YES

NO

1

Is there damage or improper connection in the
HSA control unit and the speed sensor con-
nector?

—

Go to Step2

Go to Step3

2

Measure the resistance between the speed
sensor connector terminal 3 “J-32” and the
control unit connector terminal 17 “B-285”
(with the connector disconnected). Is the mea-
surement completed?

Less than 5

Ω

Go to Step4

Go to Step5

3

Repair the connector.

Is the repair completed?

—

Go to Step4

Go to Step3

4

Measure the resistances between the speed
sensor connector terminal 2 “J-32” and the
body ground (with the connector discon-
nected). Is the measurement completed?

Less than 5

Ω

Go to Step6

Go to Step7

5

Repair the open circuit, connector disconnec-
tion, etc. between 3 “J-32” and 17 “B-285”
(with the connector disconnected).

Is the repair completed?

—

Go to Step6

Go to Step5

6

Check for battery voltage between the speed
sensor connector terminal 1 “J-32” and 2 “J-
32” (with the connector disconnected). Is the
measurement completed?

10V or more

Go to Step8

Go to Step9

7

Repair the open circuit, improper grounding,
etc. between 2 “J-32” and “B-1” (with the con-
nector disconnected).

Is the repair completed?

—

Go to Step8

Go to Step7

8

Measure the sensor output voltage between
the speed sensor connector terminal 3 “J-32”
and 2 “J-32”. Is the measurement completed?

2V

±1V — 

14V+1V — 

2V

Go to Step10

Go to Step11

9

Repair the open circuit, connector disconnec-
tion, etc. between 11 “B-53” (meter) and 1 “J-
32” (with the connector disconnected).

Is the repair completed?

—

Go to Step10

Go to Step9

10

Measure the resistance between the meter
connector terminals 14 “B-52” and 11 “B-53”.
Is the value 390 

Ω± 5% (with the connector

disconnected)?

390

Ω±5%

Go to Step12

Go to Step13

11

Replace the speed sensor.

Is the repair completed?

—

Go to Step14

Go to Step11

12

Replace the HSA control unit.

Is the repair completed?

—

Go to Step14

Go to Step12

13

Replace the flexible substrate (printed circuit
board) of the meter.

Is the repair completed?

—

Go to Step14

Go to Step13

14

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

Is this step completed?

—

—

Go to Step14

5A5-26 HSA (HILL START AID)

N5A3024E