2004 ISUZU TF SERIES warning

RESTRAINT CONTROL 9A1-5

The SRS control unit displays the trouble codes by
flashing the warning lamp. Each code that is displayed
will consist of a number of flashes which represents the
tens digit, a 1.2 second pause, following by a number of
flashes which represents the ones digit of the code.
Each code is displayed one time before moving on to
the next code. After all of the codes have been
displayed, the entire code sequence will continually by
repeated until ground is removed from terminal 4 of the
DLC connector.


Two special codes exist when reading in the flash code
mode (Flash Code 12 and Flash Code 13). “Flash
Code 12” will always be the first code displayed when
the flash code mode is enable Code 12 is not an
indication of a SRS problem but an indication that the
flash code mode has been enabled. If there are no
active or history codes present, the SRS control unit will
display code 12 until ground is removed from the DLC
connector at terminal 4. “flash Code 13” will be
displayed if history codes are present. To read the
history codes a scan tool must be used.


060R300051
DATA LIST (Tech 2)









DISPLAY on Tech 2 UNIT VALUE
Driver Airbag Loop
Enabled/Disabled
Passenger Airbag Loop
Enabled/Disabled
System Voltage V 12.0
Driver Seat Belt Status
Not Backled/Backled

RESTRAINT CONTROL 9A1-7

System Schematic


RTW49JLF000101

SRS Diagnostic System Check
The diagnostic procedures used in this section are
designed to find and repair SRS malfunctions. To get
the best results, it is important to use the diagnostic
charts and follow the sequence listed below:
A
Perform the “SRS Diagnostic System Check.”

The “SRS Diagnostic System Check” must be the
starting point of any SRS diagnostics. The “SRS
Diagnostic System Check” checks for proper “AIR
BAG” warning lamp operation, the ability of the SRS
control unit to communicate through the “Serial
Data” line and whether SRS diagnostic trouble codes
exist.

B
Refer to the proper diagnostic chart as directed by
the “SRS Diagnostic System Check.”

The “SRS Diagnostic System Check” will lead you to
the correct chart to diagnose any SRS malfunctions.
Bypassing these procedures may result in extended
diagnostic time, incorrect diagnosis and incorrect
parts replacement.
C
Repeat the “SRS Diagnostic System Check” after
any repair or diagnostic procedures have been
preformed.

Performing the “SRS Diagnostic System Check”
after all repair or diagnostic procedures will ensure
that the repair has been made correctly and that no
other malfunctions exist

9A1-8 RESTRAINT CONTROL SYSTEM

Circuit Description
When the ignition switch is first turned “ON”, “Ignition 1”
voltage is applied from the “SRS” fuse to the SRS
control unit at the “Ignition 1” input terminals “35”. The
SRS control unit responds by flashing the “AIR BAG”
warning lamp seven times, while performing tests on
the SRS.

Notes On System Check Chart
1.
The “AIR BAG” warning lamp should flash seven
times after ignition is first turned “ON”.
2.
After the “AIR BAG” warning lamp flashes seven
times, it should turn “OFF”
3.
This test checks for the proper operation of the
“Serial Data” line. This test will also determine
whether history diagnostic trouble codes are stored
and, if so, identify them.
4.
Improper operation of the “AIR BAG” warning lamp
is indicated. This test differentiates a warning lamp
stays “ON” condition from a warning lamp does not
come “ON” condition.
5.
This test checks for proper operation of the “Serial
Data” line. This test will also identify the stored
diagnostic trouble codes and whether they are
current or history.
Diagnostic Aids
The order in which diagnostic trouble codes are
diagnosed is very important. Failure to diagnose the
diagnostic trouble codes in the order specified may
result in extended diagnostic time, incorrect diagnosis
and incorrect parts replacement.


SRS Diagnostic System Check
Step Action Yes No
1 Note the “Air Bag” warning lamp as ignition switch is turned “ON.”
Does the “AIR BAG” warning lamp flash seven 7 times? Go to Step 2 Go to Step 3
2 Note the “AIR BAG” warning lamp after it flashed 7 times.
Does the “AIR BAG” warning lamp go “OFF”? Go to Step 4 Go to Step 5
3 Note the “AIR BAG” warning lamp as ignition switch is turned
“ON”.
Does the “AIR BAG” warning lamp come “ON” steady? Go to Chart B. Go to Chart C.
4
1.
Note the “AIR BAG” warning lamp as that ignition switch is
turned “ON.”

Ignition switch “OFF.”

2.
Connect a scan tool to data link connector.

3.
Follow direction given in the scan tool instruction manual.

Ignition switch “ON.”

4.
Request the SRS diagnostic trouble code display, recode all
history diagnostic trouble code(s). specify as such, on repair
order
Is (are) diagnostic trouble code(s) displayed? Ignition switch
“OFF.”
When DTC B1000 is
set, go to DTC
B1000 Chart.
For all other history
codes refer to
“Diagnostic Aids”
For that specific
DTC.
A history DTC
indicates the
malfunction has
been repaired or is
intermittent. SRS is functional
and free of
malfuncitons, no
further diagnosis is
required.
If scan tool indicated
“NO DATA
RECEIVED,” refer to
chassis electrical
section 8.

9A1-10 RESTRAINT CONTROL SYSTEM

Chart A SRS control unit Integrity Check


RTW49JLF000101

Circuit Description
When the SRS control unit recognizes “Ignition 1”
voltage, applied to terminals “35”, is greater than 9
volts, the “AIR BAG” warning lamp is flashed 7 times to
verify operation. At this time the SRS control unit
performs “Turn–ON” tests followed by “Continuous
Monitoring” tests. When a malfunction is detected, the
SRS control unit sets a current diagnostic trouble code
and illuminates the “AIR BAG” warning lamp. The SRS
control unit will clear current diagnostic trouble codes
and move them to a history file when the malfunction is
no longer detected and/or the ignition switch is cycled,
except for DTCs B0051 and B0053.

Chart Test Description
Number(s) below refer to step number(s) on the
diagnostic chart:
1.
This test confirms a current malfunction. If no
current malfunction is occurring (history DTC set)
the “Diagnostic Aids” for the appropriate diagnostic
trouble code should be referenced. The SRS control
unit should not be replaced for a history diagnostic
trouble code.
2.
This test checks for a malfunction introduced into the
SRS during the diagnostic process. It is extremely
unlikely that a malfunctioning SRS control unit would
cause a new malfunction to occur during the
diagnostic process.

RESTRAINT CONTROL 9A1-11

3.
When all circuitry outside the SRS control unit has
been found to operate properly, as indicated by the
appropriate diagnostic chart, then and only then
should the SRS control unit be replaced.


Chart A SRS control unit Integrity Check
WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SRS CONTROL
UNIT. NEVER STRIKE OR JAR THE SRS CONTROL UNIT. NEVER POWER UP THE SRS WHEN THE SRS
CONTROL UNIT IS NOT RIGIDLY ATTACHED TO THE VEHICLE. ALL SRS CONTROL UNIT AND MOUNTING
BRACKET FASTENERS MUST BE CAREFULLY TORQUED AND THE ARROW MUST BE POINTING TOWARD
THE FRONT OF THE VEHICLE TO ENSURE PROPER OPERATION OF THE SRS. THE SRS CONTROL UNIT
COULD BE ACTIVATED WHEN POWERED WHILE NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD
CAUSE DEPLOYMENT AND RESULT IN PERSONAL INJURY

Step Action Yes No
1

1. This chart assumes that the “SRS Diagnostic System
Check” and either a symptom chart or a diagnostic trouble
code chart diagnosis have been performed. When all
circuitry outside the SRS control unit has been found to
operate properly, as indicated by the appropriate diagnostic
chart, and the symptom or DTC remains current, the
following

2. Diagnostic procedures must be performed to verify the need
for SRS control unit replacement.

3. Ignition switch “OFF”.
4. Reconnect all SRS components, ensure all components are
properly mounted.

5. Ensure the ignition switch has been “OFF” for at least 15
seconds.

6. Note “AIR BAG” warning lamp as ignition switch is turned
“ON.”
Does warning lamp flash 7 times then go “OFF”? The symptom or
DTC is no longer
occurring.
Clear SRS
diagnostic trouble
codes.
Repeat “SRS
Diagnostic System
Check” Go to Step 2
2 Using a scan tool request diagnostic trouble code display.
Is the same symptom or DTC occurring as was when the “SRS
Diagnostic System Check” was first performed? Go to Step 3 Ignition switch
“OFF”.
Go to the
appropriate chart for
the indicated
malfunction.
3
1. Clear “SRS Diagnostic Trouble Codes”.

2. Ignition switch “OFF” for at least two minutes.

3. Note “AIR BAG” warning lamp as ignition switch is turned
“ON.”
Does warning lamp flash 7 times then go “OFF”? SRS is functional
and free of
malfunctions.
No further diagnosis
is required.
Go to Step 4 Ignition switch
“OFF”.
Replace SRS control
unit.
Go to Step 4
4 Reconnect all SRS components, ensure all components are
properly mounted.
Was this step finished? Repeat the “SRS
Diagnostic System
Check” Go to Step 4

9A1-12 RESTRAINT CONTROL SYSTEM

Chart B “AIR BAG” Warning Lamp Comes “ON” Steady


RTW49JLF000101

Circuit Description
When the ignition switch is first turned “ON”, “Ignition 1”
voltage is applied from the “METER” fuse to “AIR
BAG”, warning lamp which is connected to “SRS
Warning Lamp”, terminal “39”. The “SRS” fuses appl
y
system voltage to the “Ignition 1” inputs, terminals “35”.
The SRS control unit responds by flashing the “AIR
BAG” warning lamp 7 times. If “Ignition 1” is less than
9 volts, the “AIR BAG” warning lamp will come “ON”
solid with no DTCs set.
Chart Test Description
Number(s) below refer to step number(s) on the
diagnostic chart:
2.
This test checks for an open in the “Ignition 1” circuit
to the SRS control unit.
3.
This test checks for the voltage of “Ignition 1”.
4.
This test determines whether the malfunction is a
short to ground in SRS waring lamp circuit.

RESTRAINT CONTROL 9A1-13

Chart B “AIR BAG” warning lamp comes “ON” Steady

Step Action Yes No
1

1. When measurements are requested in this chart use 5-8840-
0285-0 DVM with correct terminal adapter from 5-8840-
0385-0.

2. Ignition switch “OFF.”

3. Connect scan tool to data link connector, follow directions as
given in the scan tool instruction MANUAL.

4. Ignition switch “ON.”

5. Request SRS diagnostic trouble code display.
Dose scan tool indicate “No Data Received”? Go to Step 2 Go to Step 3
2

1. Ignition switch “OFF”.

2. Inspect SRS control unit harness connector connection to
SRS control unit.
Is it securely connected to the SRS control unit? Ignition switch
“OFF.”
Replace SRS
control unit.
Go to Step 5 Connect SRS
control unit
securely to de–
activate shorting
clip in SRS control
unit harness
connector.
Go to Step 5
3 Using scan tool, request SRS data list.
Is “ignition” more than 9 volts? Go to Step 4 Ignition switch
“OFF.”
Replace SRS
control unit.
Go to Step 5
4

1. Ignition switch “OFF.”

2. Disconnect SRS coil and passenger air bag assemblies.
yellow connector located at base of steering column and
behind the glove box assembly.
Disconnect SRS control unit.

3. Disconnect the connector of “SRS Warning Lamp” of
instrument cluster.

4. Measure resistance from SRS control unit harness connector
terminal “40” to ground.
Does 5-8840-0285-0 DVM display “OL” (Infinite)? Go to Chart A Replace SRS
harness.
Go to Step 5
5 Reconnect all SRS components, ensure all components are
properly mounted.
Was this step finished? Repeat the “SRS
Diagnostic System
Check” Go to Step 5

9A1-14 RESTRAINT CONTROL SYSTEM

Chart C “AIR BAG” Warning Lamp Does Not Come “ON” Steady


RTW49JLF000101

Circuit Description
When the ignition switch is first turned “ON”, “Ignition 1”
voltage is applied from the “METER” fuse to the “AIR
BAG” warning lamp which is connected to “SRS
Warning Lamp”, terminal “39”. The “SRS” fuse appl
y
system voltage to the “Ignition 1” inputs, terminals “35”.
The SRS control unit responds by flashing the “AIR
BAG” warning lamp seven times. If “Ignition 1” is more
than 16 volts, the “AIR BAG” warning lamp will be still
“OFF” solid with no DTCs set.

Chart Test Description
Number(s) below refer to step number(s) on the
diagnostic chart:
1.
This test decides whether power is available to SRS
control unit warning lamp power feed circuit.
2.
This test determines whether the voltage is present
in the warning lamp circuit.
3.
This test determines if the malfunction is in the
instrument cluster.
4.
This test checks for open in the warning lamp
circuitry.
5.
This test isolates the SRS warning lamp circuit and
checks for a short in the SRS warning lamp circuit to
B+.
8.
This test checks for a short from the SRS control
unit warning lamp power feed circuit to ground.
9.
This test determines whether the short to ground is
due to a short in the wiring.