9J1–1
RESTRAINT CONTROL SYSTEM
RESTRAINT CONTROL SYSTEM
CONTENTS
Service Precaution 9J1–1. . . . . . . . . . . . . . . . . . . . . .
Diagnostic Information 9J1–2. . . . . . . . . . . . . . . . . . .
System Schematic 9J1–4. . . . . . . . . . . . . . . . . . . . . .
SRS Diagnostic System Check 9J1–4. . . . . . . . . . . .
Chart A SDM Integrity Check 9J1–6. . . . . . . . . . . . .
Chart B “AIR BAG” Warning Lamp
Comes “ON” Steady 9J1–8. . . . . . . . . . . . . . . . . . . .
Chart C “AIR BAG” Warning Lamp
Does Not Come “ON” Steady 9J1–10. . . . . . . . . . . . .
DTC 15 Passenger Deployment Loop
Resistance High 9J1–13. . . . . . . . . . . . . . . . . . . . . . . .
DTC 16 Passenger Deployment loop
Resistance Low 9J1–15. . . . . . . . . . . . . . . . . . . . . . . .
DTC 17 Passenger Deployment Loop
Open 9J1–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC 18 Passenger Deployment Loop
Short To Ground 9J1–19. . . . . . . . . . . . . . . . . . . . . . . .
DTC 19 Passenger Deployment Loop
Short To B+ 9J1–21. . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC 21 Driver Deployment Loop
Resistance High 9J1–23. . . . . . . . . . . . . . . . . . . . . . . .
DTC 22 Driver Deployment Loop
Resistance Low 9J1–26. . . . . . . . . . . . . . . . . . . . . . . .
DTC 24 Driver Deployment Loop
Short To Ground 9J1–29. . . . . . . . . . . . . . . . . . . . . . . .
DTC 25 Driver Deployment Loop
Short To B+ 9J1–31. . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC 26 Driver Deployment Loop Open 9J1–33. . . . DTC 51 Air Bag Deployment Event
Commanded 9J1–35. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC 53 Deployment Commanded With
Deployment Loop Fault Or Energy
Reserves Out Of Range 9J1–37. . . . . . . . . . . . . . . . .
DTC 61 Warning Lamp Circuit Failure 9J1–39. . . . .
DTC 71 Internal SDM Fault 9J1–41. . . . . . . . . . . . . .
DTC 29 Passenger Pretensioner Loop
Short To Ground 9J1–43. . . . . . . . . . . . . . . . . . . . . . . .
DTC 31 Passenger Pretensioner Loop
Resistance High 9J1–45. . . . . . . . . . . . . . . . . . . . . . . .
DTC 32 Passenger Pretensioner loop
Resistance Low 9J1–47. . . . . . . . . . . . . . . . . . . . . . . .
DTC 33 Passenger Pretensioner Loop
Short To Voltage 9J1–49. . . . . . . . . . . . . . . . . . . . . . . .
DTC 34 Passenger Pretensioner Loop
Open 9J1–51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC 41 Driver Pretensioner Loop
Resistance High 9J1–53. . . . . . . . . . . . . . . . . . . . . . . .
DTC 42 Driver Pretensioner Loop
Resistance Low 9J1–55. . . . . . . . . . . . . . . . . . . . . . . .
DTC 44 Driver Pretensioner Loop
Open 9J1–57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC 45 Driver Pretensioner Loop
Short To Ground 9J1–59. . . . . . . . . . . . . . . . . . . . . . . .
DTC 46 Driver Pretensioner Loop
Short To Voltage 9J1–61. . . . . . . . . . . . . . . . . . . . . . . .
DTC 52 Pretensioner Deployment
Event Commanded 9J1–63. . . . . . . . . . . . . . . . . . . . .
Service Precaution
WARNING: IF SO EQUIPPED WITH A
SUPPLEMENTAL RESTRAINT SYSTEM (SRS),
REFER TO THE SRS COMPONENT AND WIRING
LOCATION VIEW IN ORDER TO DETERMINE
WHETHER YOU ARE PERFORMING SERVICE ON OR
NEAR THE SRS COMPONENTS OR THE SRS
WIRING. WHEN YOU ARE PERFORMING SERVICE
ON OR NEAR THE SRS COMPONENTS OR THE SRS
WIRING, REFER TO THE SRS SERVICE
INFORMATION. FAILURE TO FOLLOW WARNINGS
COULD RESULT IN POSSIBLE AIR BAG
DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (Paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.
RESTRAINT CONTROL SYSTEM 9J1–2
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 proper
“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 Sensing and Diagnostic Module (SDM) maintains a
history record of all diagnostic codes that have beendetected 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
ISUZU 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 memory card 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 SDM “Serial Data” output
(terminal 24) to the DLC connector (terminal 9).
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 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 SDM low and signals the SDM to enter the flash
code diagnostic display mode.
9J1–7
RESTRAINT CONTROL SYSTEM
Chart A SDM Integrity Check
WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR JAR THE SDM. NEVER POWER UP THE SRS WHEN THE
S D M I S N O T R I G I D LY AT TA C H E D T O T H E V E H I C L E . A L L S D M A N D M O U N T ING 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 SDM COULD BE ACTIVATED WHEN POWERED WHILE
NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD CAUSE DEPLOYMENT AND RESULT IN
PERSONAL INJURY.
Step
ActionYe sNo
11. 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
SDM 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 SDM 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 turn on 3.5 seconds 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
2Using 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
31. 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 turn on 3.5 seconds then go “OFF”?SRS is functional
and free of
malfunctions
No further
diagnosis is
required
Go to Step 4
Ignition switch
“OFF”
Replace SDM
Go to Step 4
4Reconnect all SRS components, ensure all components are
properly mounted.
Was this step finished?Repeat the “SRS
Diagnostic
System Check”
Go to Step 4
9J1–11
RESTRAINT CONTROL SYSTEM
Chart C “AIR BAG” Warning Lamp Does Not Come “ON” Steady
StepActionYe sNo
11. 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. Remove and inspect “C–10” fuse (meter) to the “AIR BAG”
warning lamp.
Is fuse good?
Go to Step 2Go to Step 7
21. Ignition switch “OFF.”
2. Disconnect SRS coil and passenger air bag assemblies.
Yellow 2–pin connector located at base of steering column and
behind the glove box assembly.
3. Disconnect SDM.
4. Ignition switch “ON.”
5. Measure voltage on SDM harness connector from terminal “7”
to terminal “6” (ground).
Is system voltage present on terminal “7”?
Go to Step 4Go to Step 3
31. Ignition switch “OFF.”
2. Remove instrument meter cluster.
3. Check for proper connection to instrument cluster at
IB04–WHT/RED terminal.
4. If ok, then remove and inspect “AIR BAG” bulb.
Is bulb good?
Go to Step 5
Replace bulb
Go to Step 6
41. Ignition switch “OFF.”
2. Disconnect instrument meter cluster harness connector.
3. Ignition switch “ON.”
4. Measure voltage on SDM harness connector from terminal “7”
to terminal “6” (GROUND).
Is voltage 1 volt or less?
Go to Chart A
Replace SRS
harness
Go to Step 6
51. Install bulb.
2. Measure resistance from instrument meter cluster harness
connector IB04–WHT/RED terminal to SDM harness
connector terminal “7”.
Is resistance 5.0 ohms or less?Service
instrument meter
cluster
Install instrument
meter cluster
Go to Step 6
Replace SRS
harness
Go to Step 6
6Reconnect all SRS components, ensure all components are
properly mounted.
Was this step finished?Repeat the “SRS
Diagnostic
System Check”
Go to Step 6
7Perform chart C.
Was this step finished?
Go to Step 8Go to Step 1
81. Replace “C–10” fuse.
2. Ignition switch “ON” wait 10 Seconds then ignition switch “Off.”
3. Remove and inspect “C–10” fuse.
Is fuse good?
Install “C–10”
fuse
Go to Step 10
Go to Step 9
RESTRAINT CONTROL SYSTEM 9J1–36
DTC 51 Air Bag Deployment Event Commanded
WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR JAR THE SDM. NEVER POWER UP THE SRS WHEN THE
SDM IS NOT RIGIDLY ATTACHED TO THE VEHICLE. ALL SDM 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 SDM COULD BE ACTIVATED WHEN POWERED WHILE
NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD CAUSE DEPLOYMENT AND RESULT IN
PERSONAL INJURY.
Step
ActionYe sNo
1Was the “SRS Diagnostic System Check” performed?
Go to Step 2
Go to the “SRS
Diagnostic
System Check”
2Ignition switch “OFF.”
Have air bag assemblies deployed?Replace
components and
perform
inspections as
directed in
“repairs and
inspections
required after an
accident” in this
section
Clear diagnostic
trouble codes
Repeat “SRS
Diagnostic
System Check”
Go to Step 3
3Inspect front of vehicle and undercarriage for sings of impact.
Were signs of impact found?Replace
components and
perform
inspections as
directed in
“Repairs and
Inspections
Required After An
Accident” in this
section
Clear diagnostic
trouble codes
Repeat “SRS
Diagnostic
System Check”
Ignition switch
“OFF”
Replace SDM
Reconnect all
SRS system
components,
ensure all
components are
properly mounted
Repeat “SRS
Diagnostic
System Check”
RESTRAINT CONTROL SYSTEM 9J1–38
DTC 53 Deployment Commanded WITH Deployment Loop Fault Or Energy Reserves Out
Of Range
WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR JAR THE SDM. NEVER POWER UP THE SRS WHEN THE
SDM IS NOT RIGIDLY ATTACHED TO THE VEHICLE. ALL SDM 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 SDM COULD BE ACTIVATED WHEN POWERED WHILE
NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD CAUSE DEPLOYMENT AND RESULT IN
PERSONAL INJURY.
Step
ActionYe sNo
1Was the “SRS Diagnostic System Check” performed?
Go to Step 2
Go to the “SRS
Diagnostic
System Check”
2Ignition switch “OFF.”
Have air bag assembles deployed?Replace
components and
perform
inspections as
directed in
“Repairs And
Inspections
Required After An
Accident” in this
section
Clear diagnostic
trouble codes
Repeat the “SRS
Diagnostic
System Check”
Go to Step 3
3Inspect front of vehicle and undercarriage for signs of impact.
Were signs of impact found?Replace
components and
perform
inspections as
directed in
“Repairs And
Inspections
Required After An
Accident” in this
section
Clear diagnostic
trouble codes
Repeat “SRS
Diagnostic
System Check”
Ignition switch
“OFF”
Replace SDM
Reconnect all
SRS system
components,
ensure all
components are
properly mounted
Repeat the “SRS
Diagnostic
System Check”
RESTRAINT CONTROL SYSTEM 9J1–42
DTC 71 Internal SDM Fault
WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR JAR THE SDM. NEVER POWER UP THE SRS WHEN THE
SDM IS NOT RIGIDLY ATTACHED TO THE VEHICLE. ALL SDM 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 SDM COULD BE ACTIVATED WHEN POWERED WHILE
NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD CAUSE DEPLOYMENT AND RESULT IN
PERSONAL INJURY.
CAUTION: When DTC 19 or 25 has been set, it is necessary to replace the SDM. Setting DTC 19 and 25 or 51
or 53 will also cause DTC 71 to set. When a scan tool “CLEAR CODES” command is issued and the
malfunction is no longer present, DTC 51 or 53 and DTC 71 will remain current. Ensure that the short to voltage
condition DTC 19, 25 is repaired prior to installing a replacement SDM to avoid damaging the SDM.
Step
ActionYe sNo
1Was the “SRS Diagnostic System Check” performed?
Go to Step 2
Go to the “SRS
Diagnostic
System Check”
2Note SRS “Diagnostic System Check.”
IS DTC 19 OR 25 OR 51 OR 53 ALSO SET (CURRENT OR
HISTORY)? (REFER TO NOTICE ABOVE.)Go to DTC 19 if
DTC 19 is set
Go to DTC 25 if
DTC 25 is set
Go to DTC 51 if
DTC 51 is set
Go to DTC 53 if
DTC 53 is set
Ignition switch
“OFF”
Replace SDM
Repeat the “SRS
Diagnostic
System Check”
RESTRAINT CONTROL SYSTEM 9J1–64
DTC 52 Deployment Event Commanded
WARNING: DURING SERVICE PROCEDURES. BE VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR JAR THE SDM. NEVER POWER UP THE PRETENSIONER
WHEN THE SDM IS NOT RIGIDLY ATTACHED TO THE VEHICLE. ALL SDM 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 PRETENSIONER. THE SDM COULD BE
ACTIVATED WHEN POWERED WHILE NOT RIGIDLY ATTACHED TO THE VEHICLE WHICH COULD CAUSE
DEPLOYMENT AND RESULT IN PERSONAL INJURY.
Step
ActionYe sNo
1Was the “SRS Diagnostic System Check” performed?
Go to Step 2.
Go to the “SRS
Diagnostic
System Check”
2Ignition switch “OFF.”
Have pretensioner assemblies deployed?Replace
components and
perform
inspections as
directed in
“repairs and
inspections
required after an
accident” in this
section
clear diagnostic
trouble codes
Repeat “SRS
Diagnostic
System Check”
Go to Step 3
3Inspect front of vehicle and undercarriage for sings of impact.
Were signs of impact found?Replace
components and
perform
inspections as
directed in
“Repairs and
Inspections
Required After An
Accident” in this
section
Clear diagnostic
trouble codes
Repeat “SRS
Diagnostic
System Check”
Ignition switch
“OFF”
Replace SDM
Reconnect all
SRS system
components,
ensure all
components are
properly mounted
Repeat “SRS
Diagnostic
System Check”