Isuzu N-Series. Service 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
Turn the starter
switch to OFF.
Replace the SRS
airbag. Go to
8
1. Reconnect all the parts, and check that
those are installed properly.
2. Clear the DTC.
Is this step completed?
—
Check the repair.
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 “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?
—
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)?
—
Replace the SRS
harness.Go to
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
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
Turn the starter
switch to OFF.
Replace the SRS
airbag. Go to
6
1. Reconnect all the parts, and check that
those are installed properly.
2. Clear the DTC.
Is this step completed?
—
Check the repair.
Step
Action
Value
YES
NO
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