Isuzu N-Series. Manual - part 1197

SRS CONTROL SYSTEM 9C-35

7

1. Turn the starter switch to OFF.
2. Remove the 5-8840-2421-0 SRS substi-

tute load from SRS coil assembly har-
ness connector.

3. Connect the 5-8840-2421-0 SRS substi-

tute load to the upper portion of steering
column.

4. Reconnect the SRS coil assembly har-

ness connector to the lower portion of
steering column.

5. Turn the starter switch to ON.

Is DTC 22 detected as current trouble?

—

Turn the starter 

switch to OFF. 

Replace the SRS 

coil assembly by 

referring to “SRS 

Coil Assembly” in 

SRS section. Go 

to Step8

Turn the starter 

switch to OFF. 

Replace the SRS 

airbag. Go to 

Step8

8

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 Step8

Step

Action

Value

YES

NO

9C-36 SRS CONTROL SYSTEM

DTC: 24  SRS Airbag Deployment Circuit is Shorted to Ground

Outline

Description of Circuit
Turn the starter switch to “ON”. SRS control unit per-
forms the tests to diagnose critical function fault in the
SRS control unit. Upon completion of the tests, when the
results are pass, “Ignition” voltage and deployment cir-
cuit voltage will be measured to check they are within
the normal range. SRS control unit detects ground short
circuit in the SRS airbag circuit by monitoring the voltage
of “Airbag low” terminal “8”.

Condition when DTC is Set
When “Ignition” is within the normal operational voltage.
If the voltage of “Airbag low” is less than the specified
value, the DTC 24 is set.

Action to be Taken
SRS control unit turns the “SRS” warning lamp ON and
set the DTC 24.

Condition when DTC is Cleared
When the voltage of “Airbag low” terminal goes back to
more than the specified value.

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

SRS CONTROL SYSTEM 9C-37

Description of DTC Chart Test
Numbers below indicate step numbers in the diagnostic
chart.
2. This test is to check if the location of function fault is
up to the 2-pole connector (yellow) located in the lower
portion of steering column.
3. This test is to check if the location of function fault is
in the SRS airbag deployment circuit.
4. This test is to check if the location of function fault is
in the SRS airbag deployment circuit.
5. This test is to check if the location of function fault is
in the SRS coil assembly or SRS airbag.

Point of Diagnosis
In the situations that the trouble appears intermittently, it
may be caused by ground short circuit in the SRS airbag
circuit.
Carefully check the SRS airbag deployment circuit for
wire breakage or exposed wire.

Step

Action

Value

YES

NO

1

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

—

Go to Step2

Go to “SRS sys-

tem check”.

2

1. When measurement is required in this

chart, use 5-8840-0366-0 DMM and ap-
propriate terminal adapter in 5-8840-
0385-0 Connector test adapter kit.

2. Turn the starter switch to OFF.
3. Remove the 2-pole connector (yellow) of

SRS coil assembly located in the lower
portion of steering column.

4. Connect the 5-8840-2421-0 SRS substi-

tute load to SRS harness side connector
which connects to SRS coil assembly.

5. Turn the starter switch to ON.

Is DTC 24 detected as current trouble?

—

Go to Step3

Go to Step5

3

1. Turn the starter switch to OFF.
2. Remove the SRS control unit.
3. Remove the 5-8840-2421-0 SRS substi-

tute load.

4. Measure the resistance between the

SRS control unit harness connector ter-
minals “7” and “5” (ground).

Does the 5-8840-0366-0 DMM indicate “OL”
(infinity)?

—

Go to Step4

Replace the SRS 

harness.Go to 

Step6

4

Measure the resistance between the SRS
control unit harness connector terminals “8”
and “5” (ground).

Does the 5-8840-0366-0 DMM indicate “OL”
(infinity)?

—

Go to Chart A 

SRS control unit 

function check.

Replace the SRS 

harness.Go to 

Step6

9C-38 SRS CONTROL SYSTEM

5

1. Turn the starter switch to OFF.
2. Remove the 5-8840-2421-0 SRS substi-

tute load from SRS coil assembly har-
ness connector.

3. Connect the 5-8840-2421-0 SRS substi-

tute load and an appropriate terminal
adapter in the 5-8840-0385-0 Connector
test adapter kit to the SRS airbag harness
connector located in the upper portion of
steering column.

4. Reconnect the SRS coil assembly har-

ness connector to the lower portion of
steering column.

5. Turn the starter switch to ON.

Is DTC 24 detected as current trouble?

—

Turn the starter 

switch to OFF. 

Replace the SRS 

coil assembly by 

referring to “SRS 

Coil Assembly” in 

SRS section. Go 

to Step6

Turn the starter 

switch to OFF. 

Replace the SRS 

airbag. Go to 

Step6

6

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 Step6

Step

Action

Value

YES

NO