- Occupant classification ECU receives line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to +B signal in center airbag sensor assembly communication circuit for 2 seconds
- Center airbag sensor assembly malfunction
- Occupant classification ECU malfunction
| Last Modified: 04-05-2023 | 6.11:8.1.0 | Doc ID: RM100000000VJS0 |
| Model Year Start: 2016 | Model: Sienna | Prod Date Range: [12/2015 - ] |
| Title: SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1790; Center Airbag Sensor Assembly Communication Circuit Malfunction; 2016 - 2020 MY Sienna [12/2015 - ] | ||
|
DTC |
B1790 |
Center Airbag Sensor Assembly Communication Circuit Malfunction |
DESCRIPTION
The center airbag sensor assembly communication circuit consists of the occupant classification ECU and the center airbag sensor assembly.
DTC B1790 is stored when a malfunction is detected in the center airbag sensor assembly communication circuit.
|
DTC Code |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
B1790 |
One of following conditions is met: |
|
HINT:
- When DTC B1650/32 is detected as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1790 of the occupant classification system.
- Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTCs cannot be read.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front RH seat installation bolts to see the undersurface of the seat cushion.
- In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may cause problems, such as seat rail deformation. Hold the seat up only for as long as necessary.
PROCEDURE
|
1. |
CHECK FOR DTC |
(a) Turn the ignition switch to ON, and wait for at least 60 seconds.
(b) Clear any DTCs stored in the memory (See page
![2016 - 2020 MY Sienna [12/2015 - ]; SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: DTC CHECK / CLEAR](/t3Portal/stylegraphics/info.gif)
).
HINT:
- First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
- Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
(c) Turn the ignition switch off.
(d) Turn the ignition switch to ON, and wait for at least 60 seconds.
(e) Using the Techstream, check for DTCs of the occupant classification ECU (See page
).
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.
| OK |
|
|
|
2. |
CHECK CONNECTION OF CONNECTOR |
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Check that the connectors are properly connected to the occupant classification ECU and center airbag sensor assembly. Also check that the connectors that link the front seat wire RH and No. 2 floor wire are properly connected.
OK:
Connectors are properly connected.
| NG |
|
CONNECT CONNECTORS PROPERLY |
|
|
3. |
CHECK CONNECTOR |
(a) Check that the connectors (on the center airbag sensor assembly side, occupant classification ECU side, front seat wire RH side and No. 2 floor wire side) are not damaged.
OK:
Connectors are not deformed or damaged.
| NG |
|
REPLACE HARNESS OR CONNECTOR |
|
|
4. |
CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT |
Text in Illustration
|
*1 |
Occupant Classification ECU |
*2 |
Center Airbag Sensor Assembly |
|
*3 |
Front view of wire harness connector (to Occupant Classification ECU) |
*4 |
Front view of wire harness connector (to Center Airbag Sensor Assembly) |
|
*5 |
Connector E |
*6 |
Connector B |
|
*7 |
Service Wire |
- |
- |
(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
(b) Turn the ignition switch to ON, and wait for at least 60 seconds.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
X6-8 (FSR+) - Body ground |
Ignition switch ON |
Below 1 V |
|
X6-4 (FSR-) - Body ground |
(d) Turn the ignition switch off.
(e) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(f) Using a service wire, connect terminals 12 (FSR+) and 13 (FSR-) of connector B.
NOTICE:
Do not forcibly insert the service wire into the terminals of the connector.
(g) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
X6-8 (FSR+) - X6-4 (FSR-) |
Always |
Below 1 Ω |
(h) Disconnect the service wire from connector B.
(i) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
X6-8 (FSR+) - X6-4 (FSR-) |
Always |
1 MΩ or higher |
|
X6-8 (FSR+) - Body ground |
||
|
X6-4 (FSR-) - Body ground |
| NG |
|
|
|
5. |
CHECK FOR DTC |
(a) Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.
(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
(c) Turn the ignition switch to ON, and wait for at least 60 seconds.
(d) Clear any DTCs stored in the memory (See page
).
HINT:
- First clear any DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
- Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
(e) Turn the ignition switch off.
(f) Turn the ignition switch to ON, and wait for at least 60 seconds.
(g) Using the Techstream, check for DTCs of the occupant classification ECU (See page
).
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.
| OK |
|
|
|
6. |
REPLACE OCCUPANT CLASSIFICATION ECU |
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Replace the occupant classification ECU (See page
).
HINT:
Perform the inspection using parts from a normal vehicle when possible.
|
|
7. |
REPLACE CENTER AIRBAG SENSOR ASSEMBLY |
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Replace the center airbag sensor assembly (See page
).
HINT:
Perform the inspection using parts from a normal vehicle when possible.
|
|
8. |
PERFORM ZERO POINT CALIBRATION |
(a) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to ON, and wait for at least 60 seconds.
(d) Using the Techstream, perform the zero point calibration (See page
).
|
|
9. |
PERFORM SENSITIVITY CHECK |
(a) Using the Techstream, perform the sensitivity check (See page
).
Standard range:
27 to 33 kg (59.5 to 72.8 lb)
| NEXT |
|
END |
|
10. |
CHECK FRONT SEAT WIRE RH |
Text in Illustration
|
*1 |
Occupant Classification ECU |
*2 |
Center Airbag Sensor Assembly |
|
*3 |
Front Seat Wire RH |
*4 |
No. 2 Floor Wire |
|
*5 |
Front view of wire harness connector (to Occupant Classification ECU) |
*6 |
Front view of wire harness connector (to Front Seat Wire RH) |
|
*7 |
Connector E |
*8 |
Connector D |
|
*9 |
Service Wire |
- |
- |
(a) Disconnect the front seat wire RH connector from the No. 2 floor wire.
(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
(c) Turn the ignition switch to ON, and wait for at least 60 seconds.
(d) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
LX1-1 (FSR+) - Body ground |
Ignition switch ON |
Below 1 V |
|
LX1-4 (FSR-) - Body ground |
(e) Turn the ignition switch off.
(f) Disconnect the connector from the occupant classification ECU.
(g) Using a service wire, connect terminals 8 (FSR+) and 4 (FSR-) of connector E.
NOTICE:
Do not forcibly insert the service wire into the terminals of connector.
(h) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
LX1-1 (FSR+) - LX1-4 (FSR-) |
Always |
Below 1 Ω |
(i) Disconnect the service wire from connector E.
(j) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
LX1-1 (FSR+) - LX1-4 (FSR-) |
Always |
1 MΩ or higher |
|
LX1-1 (FSR+) - Body ground |
||
|
LX1-4 (FSR-) - Body ground |
| OK |
|
REPLACE NO. 2 FLOOR WIRE |
| NG |
|
REPLACE FRONT SEAT WIRE RH |
|
|