Diagnosis System

1. Check the DLC3 (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS ).

HINT

The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough customer problem analysis must be carried out. Then the same or similar conditions and the environment in which the problem occurred in the customer's vehicle should be reproduced. No matter how experienced or skilled a technician may be, if he/she proceeds to troubleshooting without confirming the problem symptoms, he/she will likely overlook something important and make a wrong guess at some points in the repair operation. This leads to a standstill in troubleshooting.

1. Vibration method: When vibration seems to be the major cause

   HINT:

   Perform the simulation method only during the primary check period of approximately 6 seconds after the engine switch is turned on (IG).

   1. Slightly vibrate the part of the sensor considered to be the problem cause with your fingers and check whether the malfunction occurs

      HINT.

      Shaking the relays too strongly may result in open relays

   2. Slightly shake the connector vertically and horizontally
   3. Slightly shake the wire harness vertically and horizontally

      The connector joint and fulcrum of the vibration are the major areas to be checked thoroughly

      Fig 1: Shaking Connector Vertically And Horizontally

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Primary check
   1. Turn the engine switch off Wait for at least 2 seconds, then turn the engine switch on (IG) The SRS warning light comes on for approximately 6 seconds and the diagnosis of the airbag system (including the seat belt pretensioners) is performed

      HINT:

      If trouble is detected during the primary check, the SRS warning light remains on even after the primary check period of approximately 6 seconds

2. Constant check
   1. After the primary check, the center airbag sensor assembly constantly monitors the airbag system for trouble

      HINT.

      If trouble is detected during the constant check, the center airbag sensor assembly functions as follows.

      • The SRS warning light comes on
      • The SRS warning light goes off, and then comes on This blinking pattern indicates a source voltage drop. The SRS warning light goes off 10 seconds after the source voltage returns to normal
3. Review
   1. When the airbag system is normal:

      The SRS warning light comes on only during the primary check period of approximately 6 seconds after the engine switch is turned on (IG)

   2. When the airbag system has trouble.
      • The SRS warning light remains on even after the primary check period.
      • The SRS warning light goes off after the primary check, but comes on again during the constant check.
      • The SRS warning light does not come on when turning the engine switch from off to on (IG).

      HINT.

      The center airbag sensor assembly functions to keep the SRS warning light on if the airbag has been deployed.

1. Turn the engine switch on (IG), and check that the SRS warning light comes on for approximately 6 seconds (primary check)
2. Check that the SRS warning light goes off approximately 6 seconds after the engine switch is turned on (IG) (constant check)
   Fig 2: Identifying SRS Warning Light

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT.

   When any of the following symptoms occur, refer to PROBLEM SYMPTOMS TABLE  .

   • The SRS warning light comes on occasionally after the primary check period.
   • The SRS warning light comes on, but a DTC is not output.
   • The engine switch is turned from off to on (IG), but the SRS warning light does not come on.

1. Initial check
   1. Turn the engine switch on (IG).
   2. The passenger airbag ON/OFF indicator comes on for approximately 4 seconds, then goes off for approximately 2 seconds.
   3. Approximately 6 seconds after the engine switch is turned on (IG), the passenger airbag ON/OFF indicator will be ON/OFF depending on the conditions listed below.
      FUNCTION OF PASSENGER AIRBAG ON/OFF INDICATOR
      
      

      Front Passenger Seat Condition	Passenger Airbag ON/OFF Indicator		SRS Warning Light
      	ON Indicator	OFF Indicator
      Vacant	OFF	OFF	OFF
      Adult is seated	ON	OFF	OFF
      Child is seated	OFF	ON	OFF
      Child restraint system is set	OFF	ON	OFF
      Front passenger occupant classification failure	OFF	ON	ON

      HINT:

      • The passenger airbag ON/OFF indicator is based on the timing chart below in order to check the indicator light circuit.
      • When the occupant classification system has trouble, both the SRS warning light and the passenger airbag ON/OFF indicator ("OFF") come on In this case, check the DTCs in the airbag system first. Then troubleshoot the occupant classification system if DTC B1650/ 32 is detected, and troubleshoot the passenger airbag ON/OFF indicator if DTC B1660/43 is detected.
        Fig 3: Identifying Passenger Airbag ON/OFF Indicator Position

        Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Turn the engine switch on (IG)
2. Check that the passenger airbag ON/OFF indicator ("ON" and "OFF") comes on for approximately 4 seconds, then goes off for approximately 2 seconds

   HINT

   Refer to the table in step  5 regarding the passenger airbag ON/OFF indicator when the engine switch is turned on (IG) and approximately 6 seconds pass

   Fig 4: Identifying Passenger Airbag ON/OFF Indicator

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. FUNCTION OF ACTIVATION PREVENTION MECHANISM
   1. An activation prevention mechanism is built into the connector (on the center airbag sensor assembly side) of the airbag system squib circuit to prevent accidental airbag activation
   2. This mechanism closes the circuit when the connector is disconnected by bringing the short spring into contact with the terminals and insulating the circuit from external power sources to prevent accidental airbag activation
2. RELEASING OF ACTIVATION PREVENTION MECHANISM
   1. To release the activation prevention mechanism, insert a piece of paper with the same thickness as the male terminal (approximately 0.5 mm (0.020 in.)) between the terminals and the short spring to break the connection.
   2. Refer to the following illustrations concerning connectors utilizing the activation prevention mechanism and its release method.
      CAUTION: Never release the activation prevention mechanism on the squib connector even when inspecting with the squib disconnected.
      NOTE:

      • Do not release the activation prevention mechanism unless specially directed by the troubleshooting procedure.
      • To prevent the terminal and the short spring from being damaged, always use a piece of paper with the same thickness as the male terminal.
        Fig 5: Supplemental Restraint Systems - System Diagram (1 Of 2)

        Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
        Fig 6: Supplemental Restraint Systems - System Diagram (2 Of 2)

        Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
        Fig 7: Identifying Center Airbag Sensor Assembly Connectors Chart

        Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002