Isuzu N-Series. Manual - part 1202

SRS CONTROL SYSTEM 9C-55

DTC: 63  Power Supply Voltage Failure

Outline

Description of Circuit
Turn the starter switch to “ON”. SRS control unit checks
if the ignition voltage is in proper range.

Condition when DTC is Set
When ignition voltage is within or 10V to 18V for 30 sec-
onds continuously.

Action to be Taken
SRS control unit turns the “SRS” warning lamp ON and
set the DTC 63.

Condition when DTC is Cleared
When ignition voltage goes back to more than 18V.

B

ACC

ON

ST

STARTER SWITCH

METER

AIRBAG

SRS CONTROL UNIT

DATA LINK CONNECTOR

16 15 14 13 12 11 10 9

8 7 6 5 4 3 2 1

0.5

B

0.5

GY

0.5

SB

0.5

GY

0.5

SB

16

4

19

15

18

7

8

20

6

5

0.85B

0.85B

0.5

B/R

0.5

B/R

0.5

W/R

0.5

B/R

0.5

B/R

0.5

W/R

0.5

B

1.25

B

2L

3
B/Y

2

14

3W/L

8B

3W/L

40A
KEY SW

10A
SRS

AIRBAG

SRS COIL

ASSEMBLY

1

2

2

1

0.5

Y

0.5

Y/B

3

10A
METER

0.5
B/Y

18

OFF

N9A0086E

Step

Action

Value

YES

NO

1

Has the “SRS system check” been per-
formed?

—

Go to Step2

Go to “SRS sys-

tem check”.

2

Read the ignition voltage using Tech 2.

Is the ignition voltage less than 18V?

—

Go to Step3

Go to Chart A 

SRS control unit 

function check.

9C-56 SRS CONTROL SYSTEM

3

1. Turn the starter switch to OFF.
2. Check the battery voltage, specific gravi-

ty, and power supply system circuit. Cor-
rect if faulty.

Is this step completed?

—

Go to Step4

Go to Step3

4

1. Reconnect all the parts, and check that

those are installed properly.

2. Clear the DTC.

Is this step completed?

—

Check the repair.

Go to Step4

Step

Action

Value

YES

NO

SRS CONTROL SYSTEM 9C-57

DTC: 71  SRS Control Unit Internal Trouble

Outline

Description of Circuit
DTC 71 indicates possibility of function fault inside the
SRS control unit.

Condition when DTC is Set
When the function fault is detected inside the SRS con-
trol unit.

Action to be Taken
SRS control unit turns the “SRS” warning lamp ON and
set the DTC.

Condition when DTC is Cleared
This DTC code cannot be cleared. Replace the SRS
control unit. 

WARNING:

DURING SERVICE WORK, BE CAREFUL NOT TO
TAP OR SHAKE THE SRS CONTROL UNIT. ALSO,
FAILURE TO INSTALL THE SRS CONTROL UNIT TO
VEHICLE PROPERLY MAY LEAD TO MALFUNC-
TION OF THE UNIT WHEN THE STARTER SWITCH IS
TURNED TO ON. THIS MAY RESULT IN INJURY DUE
TO SUDDEN DEPLOYMENT OF SRS AIRBAG.

Caution:

When this DTC is set, all the SRS system parts (SRS
control unit, airbag, etc.) must be replaced. In addition,
This DTC cannot be cleared. Be sure to disconnect the
battery cable before replacement, otherwise it will result
malfunction of replaced SRS system parts or cause bat-
tery short circuit.

B

ACC

ON

ST

STARTER SWITCH

METER

AIRBAG

SRS CONTROL UNIT

DATA LINK CONNECTOR

16 15 14 13 12 11 10 9

8 7 6 5 4 3 2 1

0.5

B

0.5

GY

0.5

SB

0.5

GY

0.5

SB

16

4

19

15

18

7

8

20

6

5

0.85B

0.85B

0.5

B/R

0.5

B/R

0.5

W/R

0.5

B/R

0.5

B/R

0.5

W/R

0.5

B

1.25

B

2L

3
B/Y

2

14

3W/L

8B

3W/L

40A
KEY SW

10A
SRS

AIRBAG

SRS COIL

ASSEMBLY

1

2

2

1

0.5

Y

0.5

Y/B

3

10A
METER

0.5
B/Y

18

OFF

N9A0086E

9C-58 SRS CONTROL SYSTEM

Special Tool

5-8840-0366-0 DMM (digital multi-meter)
5-8840-0366-0 DMM is preferable for use of SRS diag-
nostics and repair. Use of other DMM is not authorized
for SRS diagnostic and repair.
Use of other DMM may lead SRS parts deployment.

Tech 2
Use Tech 2 to read and clear SRS diagnostic trouble
code.

Step

Action

Value

YES

NO

1

Has the “SRS system check” been per-
formed? 

—

Go to Step2

Go to “SRS sys-

tem check”.

2

Are DTCs 25, 51, 53 also set as current code
or history code (See notes mentioned above)?

—

If DTC 25 is set, 

go to DTC 25 

chart.

If DTC 51 is set, 

go to DTC 51 

chart.

If DTC 53 is set, 

go to DTC 53 

chart.

Turn the starter 

switch to OFF. 

Replace the SRS 

control unit. Per-

form “SRS system 

check”.

N9A0077E

N9A0078E