Component Definitions
SUPPLEMENTAL RESTRAINT SYSTEM (SRS) COMPONENT'SYSTEM DEFINITIONSAIR BAG
The air bag is an inflatable cloth cushion that is designed to deploy in certain frontal crashes. It supplements the seatbelt protection by distributing the impact load more evenly over the vehicle occupant's head and torso.
BE+
Be+ is a battery voltage. This represents the battery voltage at the time of the indicated measurement. With the ignition switch ON and the engine not running, the system voltage will likely be between 11.5 and 12.5 volts. At engine idle, the voltage may be 14 to 16 volts. The voltage could be as low as 10 volts during engine cranking.
BULB CHECK
Under normal operation this occurs when the ignition switch transitions from the OFF position to the RUN position. The supplemental restraint Diagnostic Energy Reserve Module (DERM) causes the AIR BAG warning lamp to flash seven times if no malfunctions are detected. The bulb test will also occur if IGNITION 1 voltage exceeds 17.1 volts and returns to the normal operating voltage range. The presents of a malfunction could prevent the DERM from flashing the warning lamp.
CKT
Circuit.
CONTINUOUS MONITORING
Test preformed by the supplemental restraint Diagnostic Energy Reserve Module (DERM) on the Supplemental Restraint System (SRS) during each 100 millisecond interval. The IGNITION 1 voltage at the DERM must be within the normal operating voltage range for continuous monitoring to occur. These tests follow the POWER-ON tests.
DATUM LINE
A base line parallel to the plane of the underbody or frame of the vehicle. All vertical measurements originate from this base line.
DEPLOY
To inflate the air bag.
DEPLOYMENT LOOP
The circuit that supply current to the inflatable restraint steering wheel inflator module to deploy the air bag.
DIAGNOSTIC TROUBLE CODE (DTC)
A DTC is a 5 digit alpha numerical designator that is used by the supplemental restraint Diagnostic Energy Reserve Module (DERM) in order to indicate specific Supplemental Restraint System malfunctions. And DTC can be displayed and cleared on a scan tool.
DRIVER CURRENT SOURCE
An output of the supplemental restraint Diagnostic Energy Reserve Module (DERM) that supplies a low resistance path to ground for the supplemental restraint steering wheel inflator module circuit during the Initiator Assembly Resistance Test.
DVM OR DVOM
Digital Volt Multimeter or Digital Volt Ohm Multimeter; J 39200.
HIGHER PRIORITY FAULT
Each diagnostic trouble code is assigned a priority. This priority is based on the detectability with other DTCs present. The priority only corresponds to the detectability of the malfunction. The priority does not relate to the critically of the malfunction with respect to deployment or non-deployment under any particular condition.
IGNITION 1
A battery voltage (B+) circuit which is only powered with the ignition switch in the RUN or START positions.
IGNITION CYCLE
With the ignition switch ON, the voltage at the supplemental restraint Diagnostic Energy Reserve Module (DERM) Ignition 1 inputs is within the normal operating voltage range for at least ten seconds before turning the ignition switch OFF.
INITIATOR
An electrical component that is inside the supplemental restraint steering wheel inflator module. When sufficient current flows, the supplemental restraint steering wheel inflator module sets off the chemical reaction which inflates the air bag.
INITIATOR ASSEMBLY RESISTANCE TEST
This test checks for the following items:
1. The correct supplemental restraint Diagnostic Energy Reserve Module (DERM) configuration for the vehicle
2. Shorts for Ignition 1 in the deployment loop
3. High resistance or opens in the Driver Side High and the Driver Side Low circuits
4. Measures the resistance of the inflator assembly.
The inflator assembly consists of the following items:
^ The initiator
^ The supplemental restraint steering wheel module coil
^ Connectors
^ Associated wiring
Each test is performed once per ignition cycle in which no malfunctions are detected during Turn-ON or Continuous Monitoring.
LH FORWARD SUPPLEMENTAL RESTRAINT
DISCRIMINATING SENSOR
A sensor on the low side (ground side) of the deployment loop. The sensor is calibrated to supply ground to the supplemental restraint steering wheel inflator module when the vehicle velocity changes are severe enough to warrant the deployment of the air bag.
NORMAL OPERATING VOLTAGE RANGE
The voltage that is measured between the supplemental restraint Diagnostic Energy Reserve Module (DERM) Ignition 1 terminal and the ground terminals. The voltage should be between 7.25 and 16 volts.
RH FORWARD SUPPLEMENTAL RESTRAINT
DISCRIMINATING SENSOR
A sensor on the low side (ground side) of the deployment loop. The sensor is calibrated to supply ground to the supplemental restraint steering wheel inflator module when the vehicle velocity changes are severe enough to warrant the deployment of the air bag.
SCAN TOOL
The scan tool is an off-board computer that is used in order to read diagnostic information from an on-board computer. This is done via the data link connector.
SERIAL DATA
Serial data is information that represents the status of the Supplemental Restraint System (SRS).
SRS
The SRS is the Supplemental Restraint System.
SRS WIRING HARNESS
The Supplemental Restraint System (SRS) Wiring Harness is made up of the wires and the connectors which electrically connect the components in the SRS.
SUPPLEMENTAL RESTRAINT ARMING SENSOR
The supplemental restraint arming sensor is on the high side (power side) of the deployment loop. The supplemental restraint arming sensor is calibrated to supply voltage to the supplemental restraint steering wheel inflator module when the velocity of the vehicle changes quickly enough to warrant arming the air bag. This is done in preparation for deployment.
SUPPLEMENTAL RESTRAINT ARMING SENSOR JUMPER HARNESS CONNECTOR
A 4-way connector that is located on the top of the LH side wheelhouse. It connects the front of the dash wiring harness to the supplemental restraint arming sensor jumper harness.
SUPPLEMENTAL RESTRAINT DIAGNOSTIC ENERGY RESERVE MODULE (DERM)
The module which provides reserve energy to the deployment loop. The DERM also performs diagnostic monitoring on all of the Supplemental Restraint System (SRS) components.
SUPPLEMENTAL RESTRAINT DISCRIMINATING SENSOR INTERMEDIATE HARNESS CONNECTOR
A 4-way connector which is located on the top of the LH side wheelhouse. It connects the front of the dash wiring harness to the forward sensor harness.
SUPPLEMENTAL RESTRAINT STEERING WHEEL INFLATOR MODULE
The supplemental restraint steering wheel inflator module is located in the steering wheel hub. The supplemental restraint steering wheel inflator module consists of the following components:
^ An inflatable bag
^ An inflator
^ An initiator
SUPPLEMENTAL RESTRAINT STEERING WHEEL MODULE COIL
The supplemental restraint steering wheel module coil consists of two coils which carry currents. These coils are attached to the steering column. The coils allow rotation of the steering wheel. They also maintain continuous contact between the deployment loop and the supplemental restraint steering wheel inflator module.
SYSTEM VOLTAGE
The voltage that is available at the battery at the time of the indicated measurement. with the ignition switch ON and the engine not running, the system voltage will likely be between 11.5 and 12.5 volts. At idle, the voltage may be 14 to 16 volts. During engine cranking, the voltage could be as low as 10 volts.
TURN ON
The supplemental restraint Diagnostic Energy Reserve Module (DERM) performs this test on the SIR system once during each ignition cycle. This is done immediately after Ignition 1 voltage is applied to the DERM and before Continuous Monitoring.
10 MINUTE LOOP TEST
The portions of the Initiator Assembly Resistance Rest that are repeated every ten minutes during an ignition cycle. This is the test that checks for shorts to Ignition 1 in the deployment loop.
36 VOLT LOOP RESERVE (36 VLR)
This is the energy supply from the supplemental restraint Diagnostic Energy Reserve Module (DERM) which provides deployment power when the vehicle voltage is low or lost in a frontal crash.
36 VLR DELAY
Charging of the 36 VLR power supply is inhibited briefly during Turn-ON. This allows the detection of certain malfunctions related to Ignition 1 voltage. These malfunctions cannot be tested with 36 volts present.
CAUTION: In order to avoid deploying the air bag when troubleshooting the Supplemental Restraint System (SRS), use only the equipment specified In this manual and the instructions given in this manual Failure to use the specified equipment as instructed could cause air bag deployment, personal injury to you or someone else, or unnecessary SRS repairs.
J 38715-A SRS DRIVER/PASSENGER LOAD TOOL
Only use J 38715-A SRS Driver/Passenger Load Tool when called for in this section. This tool is a diagnostic aid, and a safety device. The driver/passenger load tool prevents inadvertent supplemental restraint steering wheel inflator module deployment. Do not attempt to use the J 37808 SRS Column Load Tool. The connectors are incompatible.
The driver/passenger load tool has four yellow connectors attached to the load tool case. The three small connectors serve as resistive load substitutions. The large dummy connector does not serve as a load substitute. The large connector merely takes the place of the supplemental restraint Diagnostic Energy Reserve Module (DERM) connector when needed. Only use one connector at a time. Use one of the small connectors to substitute the load of the driver supplemental restraint steering wheel inflator module when you connect the driver inflator module to the supplemental restraint steering wheel module coil at the top of the column. Use another small connector to substitute the load of the supplemental restraint steering wheel inflator module and the supplemental restraint steering wheel module coil when connected to the SRS wiring harness at the base of the steering column. Use the third small connector to substitute for the load of the passenger inflator module. This vehicle is not equipped with a passenger inflator module, so you should not use the Passenger Inflator connector. The large dummy connector separates the shorting bar in the DERM harness connector when you connect the large connector in place of the DERM.
You can determine whether an inflator circuit component causes a system malfunction when you substitute the resistance of the load tool. You can also determine which component causes the malfunction. Only use the load tool when specifically called for in the diagnostic procedures.
J 39200 DIGITAL MULTIMETER
The J 39200 Digital Multimeter is the preferred digital Multimeter for use in Supplemental Restraint System (SRS) diagnosis and repair. If you do not have access to a J 39200 digital Multimeter, you may use J 34029-A. Do not use any other digital inclinometer for SRS diagnosis or repair.
SCAN TOOL
The Tech 2 scan tool reads and clears Supplemental Restraint System (SRS) diagnostic trouble codes (DTCs). The Tech 2 also provides SRS circuit values using the Data List function. Refer to the Tech 2 Operator's Manual for specific information on how to use the Tech 2. You may use a scan tool from another manufacturer. Refer to the manufacturer's instruction manual for specific instructions.
J 35616-A CONNECTOR TEST ADAPTER KIT
Use the J 35616A Connector Test Adapter kit whenever a diagnostic procedure requests that you check a terminal. Also use the adapter kit for probing a terminal. Use the appropriate adapter in order to ensure that no damage occurs to the terminal from the digital Multimeter probe. The adapter also gives an idea whether sufficient contact exists. This helps to find an open or intermittent due to poor terminal contact.