SUPPLEMENTAL RESTRAINT SYSTEM 9A-17
“Continuous Monitoring”
Tests are performed by the SRS control unit on the
SRS every 100 milliseconds while “Ignition 1” voltage
is in the normal operating voltage range at the SRS
control unit.
Data Link Connector (DLC)
Formerly “DLC”, a connector which allows
communication with an external computer, such as a
scan tool.
Datum Line
A base line parallel to the plane of the underbody or
frame from which all vertical measurements originate.
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
SRS control unit to indicate specific SRS malfunctions.
Driver Current Source
An output of the SRS control unit 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
Electrically Erasable Programmable Read Only
Memory. Memory which retains its contents when
power is removed from the SRS control unit.
Ignition Cycle
The voltage at the SRS control unit “Ignition 1” input,
with ignition switch “ON”, is within the normal operating
voltage range for at least ten seconds before turning
the ignition switch “OFF”.
Ignition 1
A battery voltage (B+) circuit which is only powered
when the ignition switch is in the ON, or START
position.
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 are performed once for each ignition cycle when
no malfunctions are detected during “Turn–ON” or
“Continuous Monitoring”. This test checks for the
correct SRS control unit configuration for the vehicle,
shorts to “Ignition 1” in the deployment loops, high
resistance or opens in the “Driver Side” and
“Passenger Side” 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 SRS control unit
“Ignition 1” terminals and “Ground” terminals is
between 9 and 16 volts.
Passenger Current Source
An output of the SRS control unit 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 front of the passenger 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 on–board computers via the data link
connector.
SRS control unit
SRS control unit 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 SRS control unit performs on the SRS
once during each ignition cycle immediately after
“Ignition 1” voltage is applied to the SRS control unit
and before “Continuous Monitoring”.