Diagnosis System

1. Check the DLC3.
   1. The vehicle's ECM conforms to ISO 9141-2 for communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and meets the ISO 9141-2 format.
      Fig 1: View Of DLC3 Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      DLC3 TERMINALS VOLTAGE OR RESISTANCE SPECIFICATIONS
      
      

      Terminal No.	Connection/Voltage or Resistance	Condition
      7	Bus + Line/Pulse generation	During Transmission
      4	Chassis Ground <==> Body Ground/1 Ω or less	Always
      16	Battery Positive <==> Body Ground/11 - 14 V	Always

   HINT:

   If the display shows UNABLE TO CONNECT TO VEHICLE when you connect the cable of the hand-held tester to the DLC3, turn the ignition switch to the ON position and operate the hand-held tester, there is a problem on the vehicle side or tool side.

   • If communication is normal when the tool is connected to another vehicle, inspect the DLC3 on the original vehicle.
   • If communication is still not possible when the tool is connected to another vehicle, the problem is probably in the tool itself. Consult the Service Department listed in the tool's instruction manual.
2. Function of the SRS warning light.
   1. Primary check.

      Turn the ignition switch to the LOCK position. Wait at least 2 seconds, then turn the ignition switch to the ON position. The SRS warning light comes on for approximately 6 seconds and the diagnosis of the SRS airbag system (including the seat belt) is performed.

      HINT:

      If trouble is detected during the primary check, the SRS warning light remains on or blinks even after the primary check period (for approximately 6 seconds) has elapsed.

   2. Constant check.

      After the primary check, the airbag sensor assy center activates the SRS airbag system and monitors it for trouble constantly.

      HINT:

      If trouble is detected during the constant check, the airbag sensor assy center functions as follows:

      • The SRS warning light comes on or blinks.
      • The SRS warning light comes on, and then goes off. This blinking pattern indicates the 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 (for approximately 6 seconds after the ignition switch is turned to the ON position).
      2. When the airbag system has trouble;
         • The SRS warning light remains on or blinks even after the primary check period has elapsed.
         • The SRS warning light goes off after the primary check, but comes on or blinks again during the constant check.
         • The SRS warning light does not come on when turning the ignition switch from the LOCK to ON position.

HINT:

The airbag sensor assy center keeps the SRS warning light ON if the airbag has been deployed.

1. Turn the ignition switch to the ON position, 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 ignition switch is turned to the ON position (constant check).
   Fig 2: View Of SRS Warning Light

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

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

• When the SRS warning light comes on occasionally even after the primary check period has elapsed, an open or short in the SRS warning light circuit is suspected.
• When the SRS warning light comes on even when the ignition switch is in the LOCK position, trouble in the power source or combination meter assy is suspected.
• When the ignition switch is turned from the LOCK to ON position, the SRS warning light does not come on.