RESTRAINT CONTROL SYSTEM 9J1±2
Diagnostic Information
Diagnostic Procedures
WARNING: W H E N FA S T E N E R S A R E R E M O V E D ,
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: T O AV O I D D E P L O Y M E N T W H E N
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 ªSRS Diagnostic System Check.º
The ªSRS Diagnostic System Checkº should always be
the starting point of any SRS diagnostics. The ªSRS
Diagnostic System Checkº checks for proper ªAIR BAGº
warning lamp operation and checks for SRS trouble
codes using both ªFlash Codeº and ªScan Toolº Methods.
2.Refer To The Proper Diagnostic Chart As Directed
By The ªSRS Diagnostic System Check.º
The ªSRS Diagnostic System Checkº 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 ªSRS Diagnostic System Checkº After
Any Repair Or Diagnostic Procedures Have Been
Performed.
Performing the ªSRS Diagnostic System Checkº 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 CodesÐFaults that are presently detected this
ignition cycle. Active codes are stored in RAM
(Random Access Memory).
2. History CodesÐAll 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 ªONº. Then follow the
manufacturer's directions for communication with the
SRS. The scan tool reads serial data from the SDM
ªSerial Dataº 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.
