Diagnosis System

1. Turn the power switch off. Wait for at least 2 seconds, then turn the power 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 malfunctions are detected during the primary check, the SRS warning light remains on even after the primary check period of approximately 6 seconds.

1. After the primary check, the center airbag sensor assembly constantly monitors the airbag system for malfunctions.

   HINT: 

   If malfunctions are 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 indicates a source voltage drop. The SRS warning light goes off 10 seconds after the source voltage returns to normal.

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 power switch is turned on (IG).

2. When the airbag system is malfunctioning:
   • 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 power 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.

HINT: 

When any of the following symptoms occur, refer to Problem Symptoms Table. 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 power switch is turned from off to on (IG), but the SRS warning light does not come on.

1. Turn the power 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 power switch is turned on (IG), the passenger airbag ON/OFF indicator will indicate ON/OFF depending on the conditions listed below.

   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 illuminates 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 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 2: Identifying Passenger Airbag On/Off Indicator Diagram

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT: 

Refer to the table in step 4 regarding the passenger airbag ON/OFF indicator when the power switch is turned on (IG) and approximately 6 seconds elapse.

Fig 6: Overview Of Terminal Twin-Lock Mechanism

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. This mechanism is designed to increase the ability of the terminal to remain connected and prevent it from accidentally being disconnected.
2. The connector has a two-piece construction consisting of the housing and spacer to securely lock the terminal using both the lance (primary lock) and spacer (secondary lock).

Fig 7: Overview Of Half Connection Prevention Mechanism

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. This mechanism is designed to prevent the connector from being connected only halfway.
2. If the connector is not completely connected, the connector is disconnected due to the spring force so that no continuity exists.

Fig 8: Overview Of Activation Prevention Mechanism

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. The activation prevention mechanism is designed to create a short circuit automatically between the positive and negative terminals of an airbag power source connector when disconnected.
2. The short spring plate contained in the connector creates a closed circuit on the airbag side (no potential difference can occur between both terminals), preventing accidental airbag deployment when servicing.

Fig 9: Identifying Connector Lock Mechanism (1)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. This mechanism is designed to prevent the connector from accidentally being disconnected.
2. Locking the connector lock button engages the locking button claw to the groove on the other side connector to connect the connector securely.

Fig 10: Identifying Connector Position Assurance (CPA) Mechanism

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. This mechanism is designed to detect when the connector is connected only halfway.
2. The CPA and female connector slide to the male connector side at the same time and the primary lock is completed when the female connector is engaged with the male connector. From this point, only the CPA slides to the male connector side and secondary lock is completed when the CPA retainer is engaged with the female connector. When the CPA and female connector ends are aligned, they are completely engaged.

Fig 11: Identifying Connector Lock Mechanism (2)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. This mechanism is designed to prevent the connector from accidentally being disconnected.
2. Sliding the connector all the way into the holder and locking the lance completes the primary lock.
3. Engaging the retainer to the holder as shown in the illustration completes the secondary lock, preventing the connector from accidentally being disconnected.

Fig 12: Identifying Improper Connection Prevention Lock Mechanism

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. This mechanism is designed to prevent the connector from being connected only halfway.
2. When the holder is connected to the center airbag sensor assembly, the unlock rib unlocks the temporarily hold lock, allowing the lever to be pushed in by rotating around the A axis.
3. Locking the lever to the holder locks the holder securely.

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.

1. To release the activation prevention mechanism, insert a piece of paper with the same thickness as the male terminal (approximately 0.5 mm (0.0197 in.)) between the terminals and short spring to break the connection.
2. Refer to the following illustrations concerning connectors utilizing the activation prevention mechanism and its release method.
   WARNING:

   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 short spring from being damaged, always use a piece of paper with the same thickness as the male terminal.
   Fig 13: Identifying Releasing Of Activation Prevention Mechanism

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002