SUPPLEMENTAL RESTRAINT SYSTEM 9J–40
3. Disconnect the yellow 2–pin connector located
behind the air bag assembly and remove air bag
assembly.Refer to “SRS Connectors” in this section
for removal and installation.
4. Disconnect horn lead connector.
827RT009
5. Remove the steering wheel attachment nut.
6. Apply a setting mark across the steering wheel and
shaft so parts can be reassembled in their original
position.
430RS004
7. Move the tires to the straight ahead position before
removing the steering wheel and remove wheel with
5–8521–0016–0.
430RT009
8. Feed wiring though the wheel and remove wheel.
9. Remove the steering lower cover and engine hood
opening lever.
10. Remove the driver knee bolster assembly.
11. Remove the steering column cover.
12. Remove air conditioning lower duct.
13. Disconnect the 12–pin wiring harness connectors
located at the base of steering column.
CAUTION: Never apply force to the steering wheel
in the direction of the shaft by using a hammer or
other impact tools in an attempt to remove the
steering wheel. The steering shaft is designed as an
energy absorbing unit.
14. Remove the combination switch assembly with SRS
coil.
SUPPLEMENTAL RESTRAINT SYSTEM9J–41
Installation
1. Install the combination switch assembly with SRS
coil.
2. Turn the SRS coil counterclockwise to full, return
about 3 turns and align the neutral mark (1).
CAUTION: W h e n t u r n i n g t h e S R S c o i l
counterclockwise to full, stop turning if resistance is
felt. Forced further turning may damage the cable in
the SRS coil.
826RW014
3. Connect the wiring harness connectors located at the
base of steering column.
4. Install the air conditioning lower duct.
5. Install the steering column cover.
CAUTION: When installing the steering column
cover, be sure to wire (through each harness) as
illustrated so that the harness starter switch,
combination switch and SRS coil may not catch
wiring.
825RS048
6. Install the driver knee bolster assembly.
7. Install the steering lower cover and engine hood
opening lever.
8. Install the steering wheel and align the setting marks.
430RS004
9. Tighten the steering wheel fixing nut to the specified
torque.
Torque: 34 Nꞏm (3.5 Kgꞏm/25 Ib ft)
10. Connect horn lead.
11. Connect air bag to wiring harness connector.
NOTE: Pass the lead wire through the tabs on the plastic
cover (wire protector) of air to prevent lead wire from
being pinches.
827RT009
12. Install air bag into steering wheel and tighten bolts to
specified sequence as shown in figure.
Torque: 8.8 Nꞏm (0.9 Kgꞏm/78 Ib in)
SUPPLEMENTAL RESTRAINT SYSTEM9J–45
3. Disconnect the yellow 2–pin connector located
behind the air bag assembly and remove air bag
assembly.Refer to “SRS Connectors” in this section
for removal and installation.
827RT009
4. Disconnect horn lead connector.
5. Remove the steering wheel attachment nut.
6. Apply a setting mark across the steering wheel and
shaft so parts can be reassembled in their original
position.
430RS004
7. Move the tires to the straight ahead position before
removing the steering wheel and removing wheel with
5–8521–0016–0.
430RT009
8. Feed wiring though the wheel and remove wheel.
9. Remove the steering lower cover and engine hood
opening lever.
10. Remove the driver knee bolster assembly.
740RT015
11. Remove the steering column cover.
12. Remove air conditioning lower duct.
13. Disconnect the wiring harness connectors located at
the base of steering column.
CAUTION: Never apply force to the steering wheel
in direction of the shaft by using a hammer or other
impact tools in an attempt to remove the steering
wheel. The steering shaft is designed as an energy
absorbing unit.
14. Remove the combination switch assembly with SRS
coil.
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.
RESTRAINT CONTROL SYSTEM 9J1–4
System Schematic
D09RW014
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 SDM
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
Circuit Description
When the ignition switch is first turned “ON”, “Ignition 1”
voltage is applied from the “C–21” fuse to the SDM at the
“Ignition 1” input terminals “12”. The SDM responds by
flashing the “AIR BAG” warning lamp turn on 3.5 seconds,
while performing tests on the SRS.
Notes On System Check Chart:
1. The “AIR BAG” warning lamp should turn on 3.5
seconds after ignition is first turned “ON”.
2. After the “AIR BAG” warning lamp turn on 3.5
seconds, 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
9J1–13
RESTRAINT CONTROL SYSTEM
DTC 15 Passenger Deployment Loop Resistance High
D09RW014
Circuit Description:
When the ignition switch is turned “ON”, the SDM will
perform tests to diagnose critical malfunctions within
itself. Upon passing these tests “Ignition 1”, and
deployment loop voltages are measured to ensure they
are within their respective normal voltage ranges. The
SDM then proceeds with the “Resistance Measurement
Test”. “Passenger Bag Low” terminal “16” is grounded
through a resister and the passenger current source
connected to “Passenger Bag High” terminal “15” allows a
known amount of current to flow. By monitoring the
voltage difference between “Passenger Bag High” and
“Passenger Bag Low” the SDM calculates the combined
resistance of the passenger air bag assembly, harness
wiring IB07–YEL/GRN and IB08–YEL/RED connector
terminal contact.
DTC Will Set When:
The combined resistance of the passenger air bag
assembly, harness wiring IB07–YEL/GRN and
IB08–YEL/RED, and connector terminal contact is above
a specified value. This test is run once each ignition cycle
during the “Resistance Measurement Test” when:
1. No “higher priority faults” are detected during
“Turn–ON”,
2. “Ignition 1” voltage is in the specified value.
Action Taken:
SDM turns “ON” the “AIR BAG” warning lamp and sets a
diagnostic trouble code.
DTC Will Clear When:
The ignition switch is turned “OFF.”
DTC Chart Test Description:
Number(s) below refer to step number(s) on the
diagnostic chart:
2. This test determines whether the malfunction is in
the SDM.
3. This test verifies proper connection of the yellow
2–pin connector.
4. This test checks for proper contact and/or corrosion
of the yellow 2–pin connector terminals.
5. The test checks for a malfunctioning passenger air
bag assembly.
6. This test determines whether the malfunction is due
to high resistance in the wiring.
Diagnostic Aids:
An intermittent condition is likely to be caused by a poor
connection at the passenger air bag assembly harness
connector terminals “1” and “2”, SDM terminal “15” and
“16”, or a poor wire to terminal connection in
IB07–YEL/GRN and IB08–YEL/RED. This test for this
diagnostic trouble code is only run while the “AIR BAG”
9J1–15
RESTRAINT CONTROL SYSTEM
DTC 16 Passenger Deployment loop Resistance Low
D09RW014
Circuit Description:
When the ignition switch is turned “ON”, the SDM will
perform tests to diagnose critical malfunctions within
itself. Upon passing these tests “Ignition 1”, and
deployment loop voltages are measured to ensure they
are within their respective normal voltage ranges. The
SDM then proceeds with the “Resistance Measurement
Test”. “Passenger Bag Low” terminal “16” is grounded
through a resistor and the passenger current source
connected to “Passenger Bag High” terminal “15” allows a
known amount of current to flow. By monitoring the
voltage difference between “Passenger Bag High” and
“Passenger Bag Low”, the SDM calculates the combined
resistance of the passenger air bag assembly, harness
wiring IB07–YEL/GRN and IB08–YEL/RED connector
terminal contact.
DTC Will Set When:
The combined resistance of the passenger air bag
assembly, harness wiring IB07–YEL/GRN and
IB08–YEL/RED, and connector terminal contact is above
a specified value. This test is run once each ignition cycle
during the “Resistance Measurement Test” when:
1. No “higher priority faults” are detected during
“Turn–ON”,
2. “Ignition 1” voltage is in the specified value.
Action Taken:
SDM turns “ON” the “AIR BAG” warning lamp and sets a
diagnostic trouble code.
DTC Will Clear When:
The ignition switch is turned “OFF.”
DTC Chart Test Description:
Number(s) below refer to step number(s) on the
diagnostic chart:
2. This test determines whether the malfunction is in
the SDM.
3. This test verifies connection of the yellow 2–pin
connector.
4. This test cheeks for proper operation of the shorting
clip in the yellow 2–pin connector.
5. The test checks for a malfunction passenger air bag
assembly.
6. This test determines whether the malfunctioning is
due to shortening in the wiring.
Diagnostic Aids:
An intermittent condition is likely to be caused by a short
between IB07–YEL/GRN and IB08–YEL/RED, or a
malfunctioning shorting clip on the passenger air bag
assembly which would require replacement of the air bag
assembly. The test for this diagnostic trouble code is only
run while “AIR BAG” warning lamp is performing the bulb
9J1–17
RESTRAINT CONTROL SYSTEM
DTC 17 Passenger Deployment Loop Open
D09RW014
Circuit Description:
When the ignition switch is turned “ON”, the SDM will
perform tests to diagnose critical malfunctions within
itself. Upon passing these tests, “Ignition 1”, and
deployment loop voltages are measured to ensure they
are within their respective normal voltage ranges. During
“Continuous Monitoring” diagnostics, a fixed amount of
current is flowing in the deployment loop. This produces
proportional voltage drops in the loop. By monitoring the
voltage difference between “Passenger Bag High” and
“Passenger Bag Low”, the SDM calculates the combined
resistance of the passenger air bag assembly, harness
wiring IB07–YEL/GRN AND IB08–YEL/RED, and
connector terminal contact.
DTC Will Set When:
The voltage difference between “Passenger Bag High”
terminal “15” and “Passenger Bag Low” terminal “16” is
above or equal to a specified value for 500 milliseconds
during “Continuous Monitoring”.
Action Taken:
SDM turns “ON” the “AIR BAG” warning lamp and sets a
diagnostic trouble code.
DTC Will Clear When:
The voltage difference between “Passenger Bag High”
terminal “15” and “Passenger Bag Low” terminal “16” is
below a specified value for 500 milliseconds during
“Continuous Monitoring”.
DTC Chart Test Description:
Number(s) below refer to step number(s) on the
diagnostic chart:
2. This test determines whether the malfunction is in
the SDM.
3. This test verifies proper connection of the yellow
2–pin connector.
4. This test cheeks for proper contact and/or corrosion
of the shorting clip in the yellow 2–pin connector
terminals.
5. The test checks for a malfunctioning passenger air
bag assembly.
6. This test determines whether the open in the wiring.
Diagnostic Aids:
An intermittent condition is likely to be caused by a poor
connection at the passenger air bag assembly harness
connector terminals“2” and “3”, SDM terminals “15” and
“16”, or an open in IB07–YEL/GRN and IB08–YEL/RED.