Section 479 (Supplemental Restraint System - Diagnostics): Pre-Check

1. Check the DLC3.

   HINT:

   The vehicle's ECM uses ISO 9141-2 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

   Fig 1: Identifying DLC3 Connector Terminal

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   DLC3 CONNECTOR TERMINAL CHECK
   
   

   Terminal No.	Connection/Voltage or Resistance	Condition
   7	Bus (+) Line/Pulse generation	During Transmission
   4	Chassis ground <--> Body ground/Below 1 Ω	Always
   16	Battery positive <--> Body ground/10 to 14 V	Always

   HINT:

   If your display shows UNABLE TO CONNECT TO VEHICLE when you have connected the cable of the OBD II scan tool or hand-held tester to the DLC3, turned the ignition switch ON and operated the scan tool, 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, so consult the Service Department listed in the tool's instruction manual.

1. Turn the ignition switch to the ON position, and check that the SRS warning light turns on for approximately 6 seconds (primary check).
2. Check that the SRS warning light turns off approximately 6 seconds after the ignition switch is turned to the ON position (constant check).
   Fig 2: Checking SRS Warning Light

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   HINT:

   When any of the following symptoms occur, refer to the "Problem Symptoms Table" (see PROBLEM SYMPTOMS TABLE  ).

   • The SRS warning light turns on occasionally, after the primary check period has elapsed.
   • The SRS warning light turns on, but DTC is not output.
   • The ignition switch is turned from the LOCK to ON position, but the SRS warning light does not turn on.

1. Check the DTCs.
   1. Connect the hand-held tester to the DLC3.
   Fig 3: Connecting Hand Held Tester To DLC3
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   2. Turn the ignition switch to the DLC3.
   3. Read the DTCs by following the prompts on the tester screen.

      HINT:

      Refer to the hand-held tester operator's manual for further details.

1. Check the DTCs (present trouble code).
   1. Turn the ignition switch to the ON position, and wait for approximately 60 seconds.
   2. Using SST, connect terminals TC and CG of the DLC3.

      SST 09843-18040

      Fig 4: Connecting Terminals TC And CG Of DLC3

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   NOTE: Connect the terminals to the correct positions to avoid a malfunction.
2. Check the DTCs (past trouble code).
   1. Using SST, connect terminals TC and CG of the DLC3.

      SST 09843-18040

      NOTE: Connect the terminals to the correct positions to avoid a malfunction.
   2. Turn the ignition switch to the ON position, and wait for approximately 60 seconds.
3. Read the DTCs.
   1. Read the blinking patterns of the DTCs. As examples, the blinking patterns for trouble codes 11 and 31 are shown in Fig 5.
      • Normal system code indication (without past trouble code)

        The light blinks twice per second.

      • Normal system code indication (with past trouble code)

        When the past trouble code is stored in the airbag sensor assy center, the light blinks only once per second.

      If there are more than 1 code, there will be a 2.5-second pause between each code. After all codes are shown, there will be a 4.0-second pause, and they all will be repeated.

      HINT:

      • If 2 or more malfunctions are found, the indication begins with the smaller numbered code.
      • If DTCs are indicated without connecting the terminals, proceed to the "TC terminal circuit". See TC TERMINAL CIRCUIT  .
        Fig 5: Reading DTC Codes

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Check Mode (Using hand-held tester) 

1. Connect the hand-held tester to the DLC3.
Fig 6: Connecting Hand-Held Tester To DLC3
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2. Turn the ignition switch ON.
3. Select the "TEST MODE", and proceed checking with the hand-held tester screen.

   HINT:

   Hand-held tester only:

   Compared to the normal mode, the check mode has an increased sensitivity to detect malfunctions. Furthermore, the same diagnostic items as ones detected in the normal mode can also be detected in the check mode.

1. Clear the DTCs.
   1. When the ignition switch is turned off, the DTCs are cleared.

      HINT:

      Some DTC may not be cleared by turning off the ignition switch. In this case, proceed to the next procedure.

   2. Using SST, connect terminals TC and CG of the DLC3, and then turn the ignition switch to the ON position.

      SST 09843-18040

   3. Disconnect terminal TC of the DLC3 within 3 to 10 seconds after the DTCs are output, and check if the SRS warning light turns on after 3 seconds.
   4. Within 2 to 4 seconds after the SRS warning light turns on, connect terminals TC and CG of the DLC3.
   5. The SRS warning light should turn off within 2 to 4 seconds after connecting terminals TC and CG of the DLC3. Then, disconnect terminal TC within 2 to 4 seconds after the SRS warning light turns off.
   6. The SRS warning light turns on again within 2 to 4 seconds after disconnecting terminal TC. Then, reconnect terminals TC and CG within 2 to 4 seconds after the SRS warning light turns on.
   7. Check if the SRS warning light turns off 2 to 4 seconds after connecting terminals TC and CG of the DLC3. Also check if the normal system code is output within 1 second after the SRS warning light turns off.

      If DTCs are not cleared, repeat this procedure until the codes are cleared.

Fig 7: DTC Clearing Procedure Chart (Using Service Wire)

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An airbag activation prevention mechanism is built into the connector for the squib circuit of the SRS.

As explained in the troubleshooting later, insert a paper with the same thickness as the male terminal between the terminal and the short spring to release it (refer to Fig 8 and Fig 9).