SUPPLEMENTAL RESTRAINT SYSTEM
9J–7
Deploy
To inflate the air bag.
Deployment Loops
The circuits which supply current to the air bag
assemblies to deploy the air bag.
Diagnostic Trouble Code (DTC)
Formerly “Code”, a numerical designator used by the
SDM to indicate specific SRS malfunctions.
Driver Current Source
An output of the SDM which applies current into the driver
air bag assembly circuit during the “Initiator Assembly
Resistance Test”.
Driver Air Bag Assembly
An assembly located in the steering wheel hub consisting
of an inflatable bag, an inflator and an initiator.
EEPROM
Electronically Erasable Programmable Read Only
Memory. Memory which retains its contents when power
is removed from the SDM.
Ignition Cycle
The voltage at the SDM “Ignition 1” inputs, with ignition
switch “ON”, is within the normal operating voltage range
for at least ten seconds before turning ignition switch
“OFF”.
Ignition 1
A battery voltage (B+) circuit which is only powered with
the ignition switch in the ON, or START positions.
Initiator
The electrical component inside the air bag assembly
which, when sufficient current flows, sets off the chemical
reaction that inflates the air bag.
“Initiator Assembly Resistance Test”
Tests performed once each ignition cycle when no
malfunctions are detected during “Turn–ON” or
“Continuous Monitoring.” This test checks for the correct
SDM configuration for the vehicle, shorts to “Ignition 1” in
the deployment loops, high resistance or opens in the
“Driver Side High”, “Driver Side Low”, “Passenger Side
High” and “Passenger Side Low” circuits and measures
the resistance of the inflator assembly consisting of: 1)
Initiators, 2) SRS coil assembly (driver side only), 3)
Connectors and associated wiring.
Normal Operating Voltage Range
The voltage measured between the SDM “Ignition 1”
terminals and “Ground” terminals is between 9 and 16
volts.
Passenger Current Source
An output of the SDM which applies current into the
passenger air bag assembly circuit during the “Initiator
Assembly Resistance Test”.
Passenger Air Bag Assembly
An assembly located in the right side of the instrument
panel consisting of an inflatable bag, an inflator and an
initiator.
Scan Tool
An external computer used to read diagnostic information
from onboard computers via the data link connector.
SDM
Sensing and Diagnostic Module which provides reserve
energy to the deployment loops, deploys the air bags
when required and performs diagnostic monitoring of all
SRS components.
Serial Data
Information representing the status of the SRS.
SRS
Supplemental Restraint System.
SRS Coil Assembly
An assembly of two current–carrying coils in the driver
deployment loop that allows the rotation of the steering
wheel while maintaining the continuous contact of the
driver deployment loop to the driver air bag assembly.
SRS Wiring Harness
The wires and connectors that electrically connect the
components in the SRS.
“Turn–ON”
Test which the SDM performs on the SRS once during
each ignition cycle immediately after “Ignition 1” voltage
is applied to the SDM and before “Continuous
Monitoring”.
Diagnosis
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 PROVE–TYPE TESTER.
INSTRUCTIONS IN THIS MANUAL MUST BE
FOLLOWED CAREFULLY, OTHERWISE PERSONAL
INJURY MAY RESULT.
Diagnostic Trouble Codes
The “SRS Diagnostic System Check” must always be the
starting point of any SRS diagnosis. The “SRS
Diagnostic System Check” checks for proper “AIR BAG”
warning lamp operation and checks for SRS diagnostic
trouble codes using the scan tool.
1. Current diagnostic trouble codes – Malfunctions that
are presently being detected. Current diagnostic
trouble codes are stored in RAM (Random Access
Memory).
2. History diagnostic trouble codes – All malfunctions
detected since the last time the history memory was
cleared. History diagnostic trouble codes are stored
in EEPROM.
Scan Tool Diagnostics
A scan tool is used to read current and history diagnostic
trouble codes and to clear all diagnostic trouble codes
after a repair is completed. The scan tool must be
updated to communicate with the SRS through a
replaceable cartridge before it can be used for SRS
diagnostics. To use the scan tool, connect it to the data
link connector and turn the ignition switch “ON”. The scan