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RESTRAINT CONTROL 9A1-3
Diagnostic Information
CAUTION: When fasteners are removed, always
reinstall them at the same location from which they
were removed. if a fastener needs to be replaced,
use the correct part number fastener for that
application. if the correct part number fastener is
not available, a fastener of equal size and strength
(or stronger) may be used. fasteners that are not
reused, and those requiring thread locking
compound will be called out. the correct torque
value must be used when installing fasteners that
require it. if the above conditions are not followed,
parts or system damage could result.
Diagnostic Procedures
WARNING: TO AVOID DEPLOYMENT WHEN
TROUBLESHOOTING THE SRS, DO NOT USE
ELECTRICAL TEST EQUIPMENT SUCH AS A
BATTERY-POWERED OR AC-POWERED
VOLTMETER, OHMMETER, ETC., OR ANY TYPE OF
ELECTRICAL EQUIPMENT OTHER THAN THAT
SPECIFIED IN THIS MANUAL. DO NOT USE A NON
POWERED, PROBE-TYPE TESTER.
INSTRUCTIONS IN THIS MANUAL MUST BE
FOLLOWED CAREFULLY, OTHERWISE PERSONAL
INJURY MAY RESULT.
The diagnostic procedures used in this section are
designed to aid in finding and repairing SRS problems.
Outlined below are the steps to find and repair SRS
problems quickly and effectively. Failure to carefully
follow these procedures may result in extended
diagnostic time, incorrect diagnosis and incorrect parts
replacement.
1. Perform The “SRS Diagnostic System Check”.
The “SRS Diagnostic System Check” should always
be the starting point of any SRS diagnostics. The
“SRS Diagnostic System Check” checks for prope
r
“AIR BAG” warning lamp operation and checks for
SRS trouble codes using both “Flash Code” and
“Scan Tool” Methods.
2. 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 problems.
Bypassing these procedures may result in extended
diagnostic time, incorrect diagnosis and incorrect
parts replacement.
3. Repeat The “SRS Diagnostic System Check”
After Any Repair Or Diagnostic Procedures Have
Been Performed.
Preforming the “SRS Diagnostic System Check”
after all repair or diagnostic procedures will assure
that the repair has been made correctly and that no
other conditions exist.
Diagnostic Codes
The SRS control unit maintains a history record of all
diagnostic codes that have been detected since the
SRS codes were last cleared during service.
1. Active Codes - Faults that are presently detected this
ignition cycle. Active codes are stored in RAM
(Random Access Memory).
2. History Codes - All faults detected since the last time
the history fault memory was cleared. History codes
are stored in EEPROM. (Electronically Erasable
Programmable Read only Memory)
How To Read Trouble Codes
All codes (Active and history) can be read (or cleared)
by using a scan tool or equivalent.
If a PDT is not available, have the vehicle serviced by
HOLDEN dealer.
How To Clear Trouble Codes
Trouble codes can only be cleared by using a Scan
Tool. If a “scan tool” is not available then inform the
owner of the stored codes and suggest that the codes
are cleared upon the next visit to an Isuzu dealership.
Scan Tool Diagnostics
A scan tool can be used to read current and history
codes and to clear all history codes after a repair is
complete. The scan tool must be updated to
communicate with the SRS through a replaceable
cartridge or a manufacturer's update before it can be
used for SRS diagnostics. To use the scan tool,
connect it to the DLC connector and turn the ignition
switch “ON”. Then follow the manufacturer's directions
for communication with the SRS. The scan tool reads
serial data from the SRS control unitSRS control unit
“Serial Data” output (terminal 21) to the DLC connector
(terminal 2).
Basic Knowledge Required
Before using this section of the Service Manual, there is
some basic knowledge which will be required. Without
this knowledge, you will have trouble using the
diagnostic procedures in this section. Use care to
prevent harm or unwanted deployment. Read all
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9A1-4 RESTRAINT CONTROL SYSTEM
cautions in the service manual and on warning labels
attached to SRS components.
Basic Electrical Circuits
You should understand the basic theory of electricity
including series and parallel circuits, and understand
the voltage drops across series resistors. You should
know the meaning of voltage (volts), current (amps),
and resistance (ohms). You should understand what
happens in a circuit with an open or a shorted wire. You
should be able to read and understand a wiring
diagram.
“Flash Code” Diagnostics
Flash code diagnostics can be used to read active
codes and to determine if history codes are present but
cannot be used to clear codes or read history codes.
Flash code diagnostics is enabled by grounding by
terminal 4 shorting to terminal 13 of the DLC connector
with the ignition switch “ON”. Grounding terminal 4 of
the DLC connector pulls the “Diagnostics Request”
input (Terminal 1) of the SRS control unit low and
signals the SRS control unit to enter the flash code
diagnostic display mode.
060R300052
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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
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9A1-6 RESTRAINT CONTROL SYSTEM
Diagnostic Trouble Codes
Choose and trace an appropriate flowchart by the numbers listed below to find fault and repair.
DTC
(Flash
Code) Description
—
(12) Diagnostic Display Mode (Flash Code only)
—
(13) Diagnostic Display Mode (Flash Code only)
B0016
(16) Passenger Airbag Squib Circuit Low Resistance
B0017
(17) Passenger Airbag Squib Circuit High Resistance
B0018
(18) Passenger Airbag Squib Circuit Voltage Range / Performance
B0022
(22) Driver Airbag Squib Circuit Low Resistance
B0024
(24) Driver Airbag Squib Circuit Voltage Range / Performance Resistance
B0026
(26) Driver Airbag Squib Circuit High Resistance
B0033
(33) ECU Connector Poor Connection
B0051
(51) Squib Circuit Activated (Clash)
B0053
(53) Deployment Command Despite Present Trouble Code
B0057
(57) Passenger Pretensioner Squib Circuit Low Resistance
B0058
(58) Passenger Pretensioner Squib Circuit High Resistance
B0059
(59) Passenger Pretensioner Squib Circuit Voltage Range / Performance
B0064
(64) Driver Pretensioner Squib Circuit Low Resistance
B0065
(65) Driver Pretensioner Squib Circuit High Resistance
B0066
(66) Driver Pretensioner Squib Circuit Voltage Range / Performance Resistance
B0670
(63) Airbag Telltale Circuit Malfunction
B1000
(72) SDM Internal Fault (SDM= SRS control unit)
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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
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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.
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RESTRAINT CONTROL 9A1-9
Step Action Yes No
5
1. Ignition switch “OFF.”
2. Connect a scan tool to data link connector.
3. Follow directions as given in the scan tool instruction
manual.
4. Ignition switch “ON.”
5. Request the SRS diagnostic trouble code display, Recode
all diagnostic trouble code(s), specifying as current or history
on repair order.
Is (are) diagnostic trouble code (s) displayed? Ignition switch
“OFF”.
When DTC B0053 is
set, go to DTC
B0053 chart.
When DTC B0051 is
set, go to DTC
B0051 chart.
When DTC B0018
is set, go to DTC
B0018 chart.
When DTC B0024
is set, go to DTC
B0024 chart.
Diagnose remaining
current DTCs from
lowest to highest.
When only history
DTCs exist, refer to
“Diagnostics Aids”
for that specific
DTC.
A history DTC
indicates the
malfunction has
been repaired or is
intermittent. If scan tool indicates
“No Data Received,”
refer to chassis
electrical section 8.
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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.