Diagnosis System

HINT: 

The most difficult case in troubleshooting is when no problem symptoms occur. In such a case, a thorough problem analysis must be carried out. A simulation of the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be carried out. No matter how much skill or experience a technician has, troubleshooting without confirming the problem symptoms will lead to important repairs being overlooked and mistakes or delays.

1. Vibration method: When vibration seems to be the major cause.
   Fig 1: Symptom Simulation Vibration Method

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

   Perform the simulation method only during the primary check period (for 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.
      NOTE:

      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.

      HINT: 

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

1. Initial check:
   1. Turn the engine switch on (IG).
   2. The passenger airbag ON/OFF indicator ("ON" and "OFF") 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 show ("ON" or "OFF") depending on the conditions listed below.

      Condition	ON Indicator	OFF Indicator
      Vacant	Off	Off
      Adult is seated	On	Off
      Child is seated	Off	On
      Child restraint system is set	Off	On
      Occupant classification system failure	Off	On

      HINT: 

      • The timing chart below is based on the operation of the passenger airbag ON/OFF indicator. Use the chart 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 for DTCs in the "Airbag System" first.
      Fig 2: Passenger Airbag On/Off Indicator - Timing Chart

      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 the previous step regarding the passenger airbag ON/OFF indicator when the engine switch is turned on (IG) and approximately 6 seconds pass.