DTC B1783: Rear Occupant Classification Sensor RH Circuit Malfunction: Procedure

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal.
3. Check that the connectors are properly connected to the occupant detection ECU and rear occupant classification sensor RH.

   OK

   The connectors are properly connected.

   HINT: 

   If the connectors are not properly connected, reconnect the connectors and proceed to the next inspection.

4. Disconnect the connectors from the occupant detection ECU and rear occupant classification sensor RH.
5. Check that the terminals of the connectors are not damaged.

   OK

   The terminals are not deformed or damaged.

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the cable to the negative (-) battery terminal.
   Fig 1: Measuring Voltage Of Front Seat Wire RH Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the engine switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   R2-2 (SVC4) - Body ground	Engine switch on (IG)	Below 1 V
   R2-4 (SIG4) - Body ground	Engine switch on (IG)	Below 1 V
   R2-6 (SGD4) - Body ground	Engine switch on (IG)	Below 1 V

4. Turn the engine switch off.
5. Disconnect the cable from the negative (-) battery terminal.
   TEXT IN ILLUSTRATION
   
   

   *1	Rear Occupant Classification Sensor RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *a	Front view of wire harness connector (to Occupant Detection ECU)

NG → See step   12 

OK: Go to next step 

1. Using a service wire, connect terminals 1 (SVC4) and 3 (SGD4), and connect terminals 2 (SIG4) and 3 (SGD4) of connector C.
   Fig 2: Measuring Resistance Of Front Seat Wire RH Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   NOTE:

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

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   R2-2 (SVC4) - R2-6 (SGD4)	Always	Below 1 Ω
   R2-4 (SIG4) - R2-6 (SGD4)	Always	Below 1 Ω

3. Disconnect the service wire from connector C.
   TEXT IN ILLUSTRATION
   
   

   *1	Rear Occupant Classification Sensor RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *4	Service Wire
   *a	Front view of wire harness connector (to Occupant Detection ECU)
   *b	Front view of wire harness connector (to Rear Occupant Classification Sensor RH)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 3: Measuring Resistance Of Front Seat Wire RH Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   R2-2 (SVC4) - R2-6 (SGD4)	Always	1 MΩ or higher
   R2-4 (SIG4) - R2-6 (SGD4)	Always	1 MΩ or higher
   R2-2 (SVC4) - R2-4 (SIG4)	Always	1 MΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Rear Occupant Classification Sensor RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *a	Front view of wire harness connector (to Occupant Detection ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 4: Measuring Resistance Of Front Seat Wire RH Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   R2-2 (SVC4) - Body ground	Always	1 MΩ or higher
   R2-4 (SIG4) - Body ground	Always	1 MΩ or higher
   R2-6 (SGD4) - Body ground	Always	1 MΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Rear Occupant Classification Sensor RH
   *2	Occupant Detection ECU
   *3	Front Seat Wire RH
   *a	Front view of wire harness connector (to Occupant Detection ECU)

NG → REPLACE FRONT SEAT WIRE RH 

OK: Go to next step 

1. Connect the connectors to the occupant detection ECU and rear occupant classification sensor RH.
2. Connect the cable to the negative (-) battery terminal.
3. Clear the DTCs stored in the occupant detection ECU. Refer to DTC CHECK / CLEAR .
4. Clear the DTCs stored in the airbag ECU assembly. Refer to DTC CHECK / CLEAR .
5. Turn the engine switch off.
6. Turn the engine switch on (IG).
7. Check for DTCs. Refer to DTC CHECK / CLEAR .

   OK

   DTC B1783 is not output.

   HINT: 

   Codes other than DTC B1783 may be output at this time, but they are not related to this check.

8. Turn the engine switch off.

NG → See step   7 

OK → See step   14 

1. Disconnect the cable from the negative (-) battery terminal.
2. Replace the occupant detection ECU with a known good one. Refer to REMOVAL .

   HINT: 

   Perform the following inspection using known good parts from another vehicle if possible.

3. Connect the cable to the negative (-) battery terminal.
4. Clear the DTCs stored in the occupant detection ECU. Refer to DTC CHECK / CLEAR .
5. Clear the DTCs stored in the airbag ECU assembly. Refer to DTC CHECK / CLEAR .
6. Turn the engine switch off.
7. Turn the engine switch on (IG).
8. Check for DTCs. Refer to DTC CHECK / CLEAR .

   OK

   DTC B1783 is not output.

   HINT: 

   Codes other than DTC B1783 may be output at this time, but they are not related to this check.

9. Turn the engine switch off.
10. Disconnect the cable from the negative (-) battery terminal.
11. Restore the occupant detection ECU that was installed for testing to its original location. Refer to REMOVAL .

NG → See step   10 

OK: Go to next step 

1. Disconnect the cable from the negative (-) battery terminal.
2. Replace the occupant detection ECU with a new one. Refer to REMOVAL .
3. Connect the cable to the negative (-) battery terminal.

NEXT: Go to next step 

1. Using the Techstream, perform Zero Point Calibration and Sensitivity Check. Refer to INITIALIZATION .

NEXT → END 

1. Disconnect the cable from the negative (-) battery terminal.
2. Replace the front seat frame with adjuster assembly RH. Refer to REMOVAL .
3. Connect the cable to the negative (-) battery terminal.

NEXT: Go to next step 

1. Using the Techstream, perform Zero Point Calibration and Sensitivity Check. Refer to INITIALIZATION .

NEXT → END 

1. Disconnect the cable from the negative (-) battery terminal.
2. Replace the front seat frame with adjuster assembly RH. Refer to REMOVAL .
   NOTE:

   Replace the front seat wire RH at the same time.

   HINT: 

   When the front seat wire RH has a short to B+, the rear occupant classification sensor RH will be damaged. Therefore, replace the front seat wire RH and the front seat frame with adjuster assembly RH, which includes the rear occupant classification sensor RH.

3. Connect the cable to the negative (-) battery terminal.

NEXT: Go to next step 

1. Using the Techstream, perform Zero Point Calibration and Sensitivity Check. Refer to INITIALIZATION .

NEXT → END