Isuzu Rodeo UE. Manual - part 641

9J1–1

RESTRAINT CONTROL SYSTEM

RODEO

RESTRAINTS

SRS CONTROL SYSTEM

CONTENTS

Service Precaution

9J1–1

. . . . . . . . . . . . . . . . . . . . . . 

Diagnostic Information

9J1–2

. . . . . . . . . . . . . . . . . . . 

Diagnostic Procedures

9J1–2

. . . . . . . . . . . . . . . . . 

Diagnostic Codes

9J1–2

. . . . . . . . . . . . . . . . . . . . . . 

How To Read Trouble Codes

9J1–2

. . . . . . . . . . . . 

How To Clear Trouble Codes

9J1–2

. . . . . . . . . . . . 

Scan Tool Diagnostics

9J1–2

. . . . . . . . . . . . . . . . . . 

Basic Knowledge Required

9J1–2

. . . . . . . . . . . . . 

Basic Electrical Circuits

9J1–2

. . . . . . . . . . . . . . . . . 

“Flash Code” Diagnostics

9J1–2

. . . . . . . . . . . . . . . 

System Schematic

9J1–3

. . . . . . . . . . . . . . . . . . . . . . 

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 Comes “ON” Steady

9J1–10

. . . . . . . . . . . . . . . . . 

DTC 15  Passenger Deployment Loop
 Resistance High

9J1–13

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 16  Passenger Deployment Loop
 Resistance Low

9J1–16

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 17  Passenger Deployment Loop Open

9J1–19

DTC 18  Passenger Deployment Loop
 Short To Ground

9J1–21

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 19  Passenger Deployment Loop
 Short To Voltage

9J1–23

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 21  Driver Deployment Loop
 Resistance High

9J1–25

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 22  Driver Deployment Loop
 Resistance Low

9J1–28

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 24  Driver Deployment Loop
 Short To Ground

9J1–31

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 25  Driver Deployment Loop
 Short To Voltage

9J1–33

. . . . . . . . . . . . . . . . . . . . . . . . 

DTC 26  Driver Deployment Loop Open

9J1–36

. . . . 

DTC 51  Deployment Event Commanded

9J1–39

. . . 

DTC 53  Deployment Commanded
 With Deployment Loop Fault Or Energy
 Reserves Out Of Range

9J1–41

. . . . . . . . . . . . . . . . . 

DTC 61  Warning Lamp Circuit Failure

9J1–43

. . . . . 

DTC 71  Internal SDM Fault

9J1–45

. . . . . . . . . . . . . . 

Service Precaution

WARNING: THIS VEHICLE HAS 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

Diagnostic Procedures

WARNING: WHEN FASTENERS ARE REMOVED,
ALWAYS REINSTALL THEN 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.

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
NONPOWERED, 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.

Performing 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 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 DTC is not available, have the vehicle serviced by
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 a 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 for SRS
diagnostics.  To use the scan tool, connect it to the DLC
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.

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 current 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 13
shorting to terminal 4 of the DLC with the ignition switch
“ON”. Grounding terminal 13 of the DLC pulls the
“Diagnostics Request” input (Terminal 1) of the SDM low
and signals the SDM to enter the flash code diagnostic
display mode.

9J1–3

RESTRAINT CONTROL SYSTEM

The SDM 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 13 of the DLC.
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 enabled 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 current or history codes
present, the SDM will display code 12 until ground is
removed from the DLC at terminal 13.  “Flash Code 13”
will be displayed if there are history codes.  To read the
history codes, a scan tool must be used.

System Schematic

D09RW002

RESTRAINT CONTROL SYSTEM

9J1–4

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
performed.
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 “SRS–1” fuse to the SDM at
the “ignition 1” input terminals “12”.  The SDM responds
by flashing the “AIR BAG” warning lamp seven times
while performing tests on the SRS.

Notes On System Check Chart:

Number(s) below refer to step number(s) on the “SRS
Diagnostic 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. 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. 

4. 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.

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.