SUPPLEMENTAL RESTRAINT SYSTEM (From August, 2004): Precaution

WARNING: This page is about a different car, the 2006 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION:

The vehicle is equipped with SRS, which consists of a driver airbag, front passenger airbag, side airbag and curtain shield airbag. Failure to carry out service operations in the correct sequence could cause the SRS to unexpectedly deploy during servicing, possibly leading to a serious accident. Further, if a mistake is made in servicing the SRS, it is possible that the SRS may fail to operate when required. Before performing servicing (including removal or installation of parts, inspection or replacement), be sure to read the following items carefully, then follow the correct procedures indicated in the article.
Wait at least 90 seconds after the ignition switch is turned to the "LOCK" position and the negative (-) terminal cable is disconnected from the battery before starting the operation. (The SRS is equipped with a back-up power source, so that if work is started within 90 seconds after disconnecting the negative (-) terminal cable of the battery, the SRS may be deployed.)
Do not expose the horn button assy, instrument panel pass l/door airbag assy, airbag sensor assy center, airbag sensor front, front seat airbag assy, side airbag sensor assy, curtain shield airbag assy, airbag sensor rear, seat position airbag sensor or occupant classification ECU directly to hot air or flames.
Be sure to perform the initialization of the occupant classification ECU if any of the following conditions occur (see INITIALIZATION ). If the initialization is not performed, the SRS may not operate properly.
- The occupant classification ECU is replaced.
- Accessories (seatback tray, seat cover, etc.) are installed to the vehicle.
- The passenger seat is removed from the vehicle, and then reinstalled or replaced.
- The passenger airbag ON/OFF indicator light ("OFF") comes on when the passenger seat is not occupied.
- The vehicle is brought to the workshop for repair due to an accident or collision.

NOTE:

Malfunction symptoms of the SRS are difficult to confirm, so DTCs are the most important source of information when troubleshooting. When troubleshooting the SRS, always inspect DTCs before disconnecting the battery.
Even in the case of a minor collision when the SRS does not deploy, the horn button assy, instrument panel pass l/door airbag assy, airbag sensor assy center, airbag sensor front, front seat airbag assy, side airbag sensor assy, curtain shield airbag assy, airbag sensor rear, seat position airbag sensor and occupant classification ECU should be inspected (see ON-VEHICLE INSPECTION ).
Before repair work, remove the airbag sensor if any kind of shock is likely to occur to the airbag sensor during the operation.
Never use SRS parts from another vehicle. When replacing the parts, replace them with new ones.
Never disassemble or repair the horn button assy, instrument panel pass l/door airbag assy, airbag sensor assy center, airbag sensor front, front seat airbag assy, side airbag sensor assy, curtain shield airbag assy, airbag sensor rear, seat position airbag sensor or occupant classification ECU in order to reuse it.
If the horn button assy, instrument panel pass l/door airbag assy, airbag sensor assy center, airbag sensor front, front seat airbag assy, side airbag sensor assy, curtain shield airbag assy, airbag sensor rear, seat position airbag sensor or occupant classification ECU has been dropped, or if there are any cracks, dents or other defects in the case, bracket or connector, replace it with a new one.
Use a volt/ohmmeter with high impedance (10 kW/V minimum) for troubleshooting the electrical circuits.
Information labels are attached to the periphery of the SRS components. Follow the instructions in the caution.
After work on the SRS is completed, perform the SRS warning light check (see DIAGNOSIS SYSTEM ).
When the negative (-) terminal cable is disconnected from the battery, the memory will be cleared. Because of this, be sure to make a record of the contents memorized in each system before starting work. When work is finished, adjust each system as it was before. Never use a back-up power supply from outside the vehicle to avoid erasing the memory in any system.
If the vehicle is equipped with a mobile communication system, see HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS .

DEPLOYMENT CONDITION
1. When the vehicle collides and the shock is greater than the specified value, the SRS is activated automatically. The airbag sensor assy center includes the safing sensor and deceleration sensor. The safing sensor was designed to be turned on at a smaller deceleration rate than the deceleration sensor. The deceleration sensor determines whether or not ignition is necessary based on signals from the airbag sensor front. Current flows to the squibs to deploy the SRS when the conditions as shown below are met.
  
  Fig 1: Communication Flow Diagram Deployment Condition (1 Of 4)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 2: Communication Flow Diagram Deployment Condition (2 Of 4)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 3: Communication Flow Diagram Deployment Condition (3 Of 4)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. The vehicle is equipped with the function to activate the SRS in case of vehicle rollover. A circuit to detect vehicle rollover is built into the airbag sensor assy center. When the conditions for vehicle rollover are met, the SRS activates as shown below.
  
  Fig 4: Communication Flow Diagram Deployment Condition (4 Of 4)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SRS CONNECTORS

HINT:

SRS connectors are located as shown.

Fig 5: Communication Diagram SRS Connectors

CONNECTOR NO/TYPE AND APPLICATION

No.	Connector Type	Application
(1)	Terminal Twin-Lock Mechanism	Connectors 2, 4, 6, 8, 10, 12, 15, 16, 17, 18, 19, 20, 21, 27, 28, 35
(2)	Airbag Activation Prevention Mechanism	Connectors 2, 4, 22, 24, 26, 28, 30, 32
(3)	Electrical Connection Check Mechanism	Connectors 1, 2, 3, 4
(4)	Half Connection Prevention Mechanism	Connectors 6, 8, 10, 20, 25, 27
(5)	Connector Lock Mechanism	Connectors 23, 29, 31

All connectors in the SRS, except the seat position airbag sensor connector and the occupant classification ECU connectors, are colored yellow to distinguish them from other connectors. These connectors have special functions, and are specially designed for the SRS. All SRS connectors use durable gold-plated terminals, and are placed in the locations shown previously above to ensure high reliability.

Fig 6: Identifying Terminal Twin-Lock Mechanism
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Terminal twin-lock mechanism:
  Each connector has a two-piece component consisting of a housing and a spacer. This design enables the terminal to be locked securely by two locking devices (the retainer and the lance) to prevent terminals from coming out.
2. Activation prevention mechanism:
  Each connector contains a short spring plate. When the connector is disconnected, the short spring plate automatically connects the positive (+) terminal and the negative (-) terminal of the squib.
  
  Fig 7: Identifying Activation Prevention Mechanism
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Electrical connection check mechanism:
  This mechanism electrically checks that the connectors are connected correctly and completely. The electrical connection check mechanism is designed so that the disconnection detection pin connects with the diagnosis terminals when the connector housing lock is locked.
  
  Fig 8: Identifying Electrical Connection Check Mechanism
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 9: Identifying Half & Complete Connection
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Half connection prevention mechanism:
  If the connector is not completely connected, the connector is disconnected due to the spring operation so that no continuity exists.
  
  Fig 10: Identifying Half Connection Prevention Mechanism
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. Connector lock mechanism:
  Locking the connector lock button connects the connector securely.
  
  Fig 11: Identifying Connector Lock Mechanism:
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DISCONNECTION OF CONNECTORS FOR HORN BUTTON ASSY AND CURTAIN SHIELD AIRBAG ASSY
1. Release the lock button (yellow part) of the connector using a screwdriver.
2. Insert the screwdriver tip between the connector and the base, and then raise the connector.
  
  Fig 12: Inserting Screwdriver Tip Between Connector & Base
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
CONNECTION OF CONNECTORS FOR HORN BUTTON ASSY AND CURTAIN SHIELD AIRBAG ASSY
1. Connect the connector.
2. Push down securely on the lock button (yellow part) of the connector. (When locking, a click sound can be heard.)
  
  Fig 13: Pushing Down Securely On Lock Button Of Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DISCONNECTION OF CONNECTOR FOR INSTR PNL PASS L/DOOR AIRBAG ASSY
1. Place a finger on the slider, slide the slider to release the lock, and then disconnect the connector.
  
  Fig 14: Placing Finger On Slider
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
CONNECTION OF CONNECTOR FOR INSTR PNL PASS L/DOOR AIRBAG ASSY
1. Connect the connector as shown. (When locking, make sure that the slider returns to its original position and a click sound can be heard.)
  HINT:
  
  When connecting, the slider will slide. Be sure not to touch the slider while connecting, as it may result in an insecure fit.
  
  Fig 15: Connecting Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DISCONNECTION OF CONNECTOR FOR FRONT SEAT AIRBAG ASSY
1. Place a finger on the slider, slide the slider to release the lock, and then disconnect the connector.
  
  Fig 16: Placing Finger On Slider
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
CONNECTION OF CONNECTOR FOR FRONT SEAT AIRBAG ASSY
1. Connect the connector as shown. (When locking, make sure that the slider returns to its original position and a click sound can be heard.)
  HINT:
  
  When connecting, the slider will slide. Be sure not to touch the slider while connecting, as it may result in an insecure fit.
  
  Fig 17: Connecting Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DISCONNECTION OF CONNECTORS FOR AIRBAG SENSOR FRONT, SIDE AIRBAG SENSOR ASSY AND AIRBAG SENSOR REAR
1. While holding both outer flank sides, slide the outer in the direction shown by the arrow.
2. When the connector lock is released, the connectors are disconnected.
  HINT:
  
  Be sure to hold both outer flank sides. Holding the top and bottom will make disconnection difficult.
  
  Fig 18: Sliding Outer While Holding Both Outer Flank Sides
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 19: Identifying Connector Lock Released
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
CONNECTION OF CONNECTORS FOR AIRBAG SENSOR FRONT, SIDE AIRBAG SENSOR ASSY AND AIRBAG SENSOR REAR
1. Connect the connector as shown. (When locking, make sure that the outer returns to its original position and a click sound can be heard.)
  HINT:
  
  When connecting, the outer will slide. Be sure not to hold the outer while connecting, as it may result in an insecure fit.
  
  Fig 20: Connecting Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002