DTC B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction: Procedure

1. Turn the power switch ON (IG).
2. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR [09/2012 - ] .
3. Clear the DTCs stored in the center airbag sensor. Refer to DTC CHECK / CLEAR [09/2012 - ] .
4. Turn the power switch OFF.
5. Turn the power switch ON (IG).
6. Check for the DTCs. Refer to DTC CHECK / CLEAR [09/2012 - ] .

   OK

   DTC B1790 is not output.

   HINT: 

   Codes other than DTC B1790 may be output at this time, but they are not related to this check.

NG → See step   2 

OK → See step   13 

1. Turn the power switch OFF.
2. Disconnect the negative (-) terminal cable from the auxiliary battery.
3. Check that the connectors are properly connected to the occupant classification ECU and the center airbag sensor.

   OK

   Connectors are properly connected.

NG → CONNECT CONNECTORS PROPERLY 

OK: Go to next step 

1. Disconnect the connectors from the center airbag sensor and the occupant classification ECU.
2. Check that the connectors (on the center airbag sensor side and occupant classification ECU side) are not damaged.

   OK

   Connectors are not deformed or damaged.

NG → REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Connect the negative (-) terminal cable to the auxiliary battery.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Turn the power switch ON (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   e10-11 (FSR+) - Body ground	Power switch ON (IG)	Below 1 V
   e10-12 (FSR-) - Body ground

4. Turn the power switch OFF.
5. Disconnect the negative (-) terminal cable from the auxiliary battery.
6. Using a service wire, connect terminals 16 (FSR+) and 22 (FSR-) of connector B.
   NOTE:

   Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

7. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   e10-11 (FSR+) - e10-12 (FSR-)	Always	Below 1 Ω

8. Disconnect the service wire from connector B.
9. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   e10-11 (FSR+) - e10-12 (FSR-)	Always	1 MΩ or higher
   e10-11 (FSR+) - Body ground
   e10-12 (FSR-) - Body ground

NG → See step   11 

OK: Go to next step 

1. Connect the connectors to the occupant classification ECU and the center airbag sensor.
2. Connect the Techstream to the DLC3.
3. Connect the negative (-) terminal cable to the auxiliary battery.
4. Turn the power switch ON (IG).
5. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR [09/2012 - ] .
6. Clear the DTCs stored in the center airbag sensor. Refer to DTC CHECK / CLEAR [09/2012 - ] .
7. Turn the power switch OFF.
8. Turn the power switch ON (IG).
9. Using the Techstream, check for the DTCs of the occupant classification ECU. Refer to DTC CHECK / CLEAR [09/2012 - ] .

   OK

   DTC B1790 is not output.

   HINT: 

   Codes other than DTC B1790 may be output at this time, but they are not related to this check.

NG → See step   6 

OK → See step   12 

1. Connect the Techstream to the DLC3.
2. Turn the power switch ON (IG).
3. Using the Techstream, save the ECU data from the ECU which was installed on the vehicle. Refer to REGISTRATION [09/2012 - ] .
4. Turn the power switch OFF.
5. Disconnect the negative (-) terminal cable from the auxiliary battery, and wait for at least 90 seconds.
6. Replace the front seat cushion assembly (occupant classification ECU). Refer to DISASSEMBLY [09/2012 - ] .
7. Connect the negative (-) terminal cable to the auxiliary battery.
8. Turn the power switch ON (IG).
9. Using the Techstream, load the previous ECU data stored in the Techstream into the new ECU. Refer to REGISTRATION [09/2012 - ] .
10. Turn the power switch OFF.
11. Turn the power switch ON (IG).
12. Clear the DTCs stored in the memory. Refer to DTC CHECK / CLEAR [09/2012 - ] .

    HINT: 

    If the DTCs are not cleared at this time, past DTCs will remain.

NEXT: Go to next step 

1. Turn the power switch ON (IG).
2. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR [09/2012 - ] .
3. Clear the DTCs stored in the center airbag sensor. Refer to DTC CHECK / CLEAR [09/2012 - ] .
4. Turn the power switch OFF.
5. Turn the power switch ON (IG).
6. Using the Techstream, check for the DTCs of the occupant classification ECU. Refer to DTC CHECK / CLEAR [09/2012 - ] .

   OK

   DTC B1790 is not output.

   HINT: 

   Codes other than DTC B1790 may be output at this time, but they are not related to this check.

NG → See step   9 

OK: Go to next step 

1. Perform the sensitivity check. Refer to INITIALIZATION [09/2012 - ] .

NEXT → END 

1. Turn the power switch OFF.
2. Disconnect the negative (-) terminal cable from the auxiliary battery, and wait for at least 90 seconds.
3. Replace the center airbag sensor. Refer to REMOVAL [09/2012 - ] .

NEXT: Go to next step 

1. Perform the sensitivity check. Refer to INITIALIZATION [09/2012 - ] .

NEXT → END 

1. Turn the power switch OFF.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Disconnect the negative (-) terminal cable from the auxiliary battery, and wait for at least 90 seconds.
3. Disconnect the front seat wire RH connector from the floor wire.
4. Connect the negative (-) terminal cable to the auxiliary battery, and wait for at least 2 seconds.
5. Turn the power switch ON (IG).
6. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   Re3-2 (FSR+) - Body ground	Power switch ON (IG)	Below 1 V
   Re3-3 (FSR-) - Body ground

7. Disconnect the front seat wire RH connector from the floor wire.
8. Disconnect the negative (-) terminal cable from the auxiliary battery.
9. Using service wire, connect terminals 16 (FSR+) and 22 (FSR-) of connector B.
   NOTE:

   Do not forcibly insert a service wire into the terminals of the connector when connecting the wire.

10. Measure the resistance according to the value(s) in the table below.

    Standard resistance

    Tester Connection	Condition	Specified Condition
    Re3-2 (FSR+) - Re3-3 (FSR-)	Always	Below 1 Ω

11. Disconnect the service wire from connector B.
12. Measure the resistance according to the value(s) in the table below.

    Standard resistance

    Tester Connection	Condition	Specified Condition
    Re3-2 (FSR+) - Re3-3 (FSR-)	Always	1 MΩ or higher
    Re3-2 (FSR+) - Body ground
    Re3-3 (FSR-) - Body ground

NG → REPLACE FLOOR WIRE 

OK → REPLACE FRONT SEAT WIRE RH