DTC B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction [08/2015 - 08/2017]: Procedure

1. Turn the ignition switch to ON, and wait for at least 60 seconds.
2. Clear any DTCs stored in the memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   HINT: 

   • First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
3. Turn the ignition switch off.
4. Turn the ignition switch to ON, and wait for at least 60 seconds.
5. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   OK

   DTC B1790 is not output.

   HINT: 

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

Result: 

OK 

USE SIMULATION METHOD TO CHECK 

(Refer to DIAGNOSIS SYSTEM [08/2015 - 08/2017] )

Result: 

NG 

See step  2

1. Turn the ignition switch off.
2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. Check that the connectors are properly connected to the occupant classification ECU and the center airbag sensor.

   OK

   Connectors are properly connected.

Result: 

NG 

CONNECT CONNECTORS PROPERLY 

Result: 

OK 

See step  3

1. Check that the connectors (on the center airbag sensor side and occupant classification ECU side) are not damaged (Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [08/2015 - 08/2019] ).

   OK

   Connectors are not deformed or damaged.

   RESULT
   
   

   Result	Proceed to
   Connectors are not deformed or damaged (for Power seat)	A
   Connectors are not deformed or damaged (for Manual seat)	B
   Connectors are deformed or damaged	C

Result: 

B 

See step  11

Result: 

C 

REPLACE HARNESS OR CONNECTOR 

Result: 

A 

See step  4

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
2. Turn the ignition switch to ON, and wait for at least 60 seconds.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   W6-8 (FSR+) - Body ground	Ignition switch ON	Below 1 V
   W6-4 (FSR-) - Body ground

4. Turn the ignition switch off.
5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
6. Using a service wire, connect terminals 12 (FSP+) and 13 (FSP-) of connector B.
   NOTE:

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

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   W6-8 (FSR+) - W6-4 (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
   W6-8 (FSR+) - W6-4 (FSR-)	Always	1 MΩ or higher
   W6-8 (FSR+) - Body ground
   W6-4 (FSR-) - Body ground

Result: 

NG 

See step  10

Result: 

OK 

See step  5

1. Connect the connectors to the occupant classification ECU and the center airbag sensor.
2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Clear any DTCs stored in the memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   HINT: 

   • First clear any DTCs stored in the occupant classification ECU and then in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
5. Turn the ignition switch off.
6. Turn the ignition switch to ON, and wait for at least 60 seconds.
7. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   OK

   DTC B1790 is not output.

   HINT: 

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

Result: 

OK 

USE SIMULATION METHOD TO CHECK 

(Refer to DIAGNOSIS SYSTEM [08/2015 - 08/2017] )

Result: 

NG 

See step  6

1. Turn the ignition switch off.
2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. Replace the occupant classification ECU (Refer to REMOVAL [08/2015 - 08/2019] ).

   HINT: 

   Perform the inspection using parts from a normal vehicle when possible.

Result: 

NEXT 

See step  7

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Using the Techstream, perform the zero point calibration (Refer to INITIALIZATION [08/2015 - 08/2019] ).

Result: 

NEXT 

See step  8

1. Using the Techstream, perform the sensitivity check (Refer to INITIALIZATION [08/2015 - 08/2019] ).

   Standard range

   27 to 33 kg (59.5 to 72.8 lb)

Result: 

NEXT 

See step  9

1. Connect the connector to the occupant classification ECU.
2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Clear any DTCs stored in the memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   HINT: 

   • First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
5. Turn the ignition switch off.
6. Turn the ignition switch to ON, and wait for at least 60 seconds.
7. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   OK

   DTC B1790 is not output.

   HINT: 

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

Result: 

OK 

END 

Result: 

NG 

REPLACE CENTER AIRBAG SENSOR ASSEMBLY 

(Refer to REMOVAL [08/2015 - 08/2017] )

1. Disconnect the front seat wire RH connector from the No. 2 floor wire.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   PW1-8 (FSP+) - Body ground	Ignition switch ON	Below 1 V
   PW1-9 (FSP-) - Body ground

5. Turn the ignition switch off.
6. Disconnect the connector from the occupant classification ECU.
7. Using a service wire, connect terminals 8 (FSR+) and 4 (FSR-) of connector E.
   NOTE:

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

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   PW1-8 (FSP+) - PW1-9 (FSP-)	Always	Below 1 Ω

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

    Standard Resistance

    Tester Connection	Condition	Specified Condition
    PW1-8 (FSP+) - PW1-9 (FSP-)	Always	1 MΩ or higher
    PW1-8 (FSP+) - Body ground
    PW1-9 (FSP-) - Body ground

Result: 

OK 

REPLACE NO. 2 FLOOR WIRE 

Result: 

NG 

REPLACE FRONT SEAT WIRE RH 

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
2. Turn the ignition switch to ON, and wait for at least 60 seconds.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   P14-8 (FSR+) - Body ground	Ignition switch ON	Below 1 V
   P14-4 (FSR-) - Body ground

4. Turn the ignition switch off.
5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
6. Using a service wire, connect terminals 12 (FSP+) and 13 (FSP-) of connector B.
   NOTE:

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

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   P14-8 (FSR+) - P14-4 (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
   P14-8 (FSR+) - P14-4 (FSR-)	Always	1 MΩ or higher
   P14-8 (FSR+) - Body ground
   P14-4 (FSR-) - Body ground

Result: 

NG 

REPLACE NO. 2 FLOOR WIRE 

Result: 

OK 

See step  12

1. Connect the connectors to the occupant classification ECU and the center airbag sensor.
2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Clear any DTCs stored in the memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   HINT: 

   • First clear any DTCs stored in the occupant classification ECU and then in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
5. Turn the ignition switch off.
6. Turn the ignition switch to ON, and wait for at least 60 seconds.
7. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   OK

   DTC B1790 is not output.

   HINT: 

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

Result: 

OK 

USE SIMULATION METHOD TO CHECK 

(Refer to DIAGNOSIS SYSTEM [08/2015 - 08/2017] )

Result: 

NG 

See step  13

1. Turn the ignition switch off.
2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
3. Replace the occupant classification ECU (Refer to REMOVAL [08/2015 - 08/2019] ).

   HINT: 

   Perform the inspection using parts from a normal vehicle when possible.

Result: 

NEXT 

See step  14

1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Using the Techstream, perform the zero point calibration (Refer to INITIALIZATION [08/2015 - 08/2019] ).

Result: 

NEXT 

See step  15

1. Using the Techstream, perform the sensitivity check (Refer to INITIALIZATION [08/2015 - 08/2019] ).

   Standard range

   27 to 33 kg (59.5 to 72.8 lb)

Result: 

NEXT 

See step  16

1. Connect the connector to the occupant classification ECU.
2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
3. Turn the ignition switch to ON, and wait for at least 60 seconds.
4. Clear any DTCs stored in the memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   HINT: 

   • First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.
   • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
5. Turn the ignition switch off.
6. Turn the ignition switch to ON, and wait for at least 60 seconds.
7. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

   OK

   DTC B1790 is not output.

   HINT: 

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

Result: 

OK 

END 

Result: 

NG 

REPLACE CENTER AIRBAG SENSOR ASSEMBLY 

(Refer to REMOVAL [08/2015 - 08/2017] )