B1773
SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1773: Belt Tension Sensor Circuit Malfunction
DTC B1773 - Belt Tension Sensor Circuit Malfunction
DTC B1776 - Seat Belt Tension Sensor Power Source Circuit Malfunction
DESCRIPTION
The seat belt tension sensor circuit consists of the occupant classification ECU and the seat belt tension sensor.
The seat belt tension sensor sends the seat belt tension signal to the occupant classification ECU.
DTC B1773 and B1776 are recorded when a malfunction is detected in the seat belt tension sensor circuit.
HINT: When DTC B1650/32 is detected as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant classification ECU. When DTC B1773 and B1776 are output, perform troubleshooting for the DTC.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the passenger seat installation bolts to access 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 damage the seat or deform the seat rails. Hold the seat only as necessary.
PROCEDURE
1. CHECK CONNECTORS
(a) Turn the engine switch off.
(b) Disconnect the cable from the negative (-) battery terminal.
(c) Check that the connectors are properly connected to the occupant classification ECU and the seat belt tension sensor.
OK:
The connectors are properly connected.
HINT: If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.
(d) Disconnect the connectors from the occupant classification ECU and the seat belt tension sensor.
(e) Check that the terminals of the connectors are not damaged.
OK:
The terminals are not deformed or damaged.
NG -- REPLACE WIRE HARNESS
OK -- Continue to next step.
2. CHECK SEAT BELT TENSION SENSOR CIRCUIT (SHORT TO B+)
(a) Connect the cable to the negative (-) battery terminal.
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
NG -- CHECK FRONT SEAT WIRE RH (SHORT TO B+)
OK -- Continue to next step.
3. CHECK SEAT BELT TENSION SENSOR CIRCUIT (OPEN)
(a) Turn the engine switch off.
(b) Disconnect the cable from the negative (-) battery terminal.
(c) Using SST, connect terminals 1 (GBT) and 3 (BT), and connect terminals 1 (GBT) and 2 (VBT) of connector E.
NOTICE: Do not forcibly insert SST into the terminals of the connector when connecting the wire.
SST: 09843-18040
(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK FRONT SEAT WIRE RH (OPEN)
OK -- Continue to next step.
4. CHECK SEAT BELT TENSION SENSOR CIRCUIT (SHORT TO GROUND)
(a) Disconnect SST from connector E.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)
OK -- Continue to next step.
5. CHECK SEAT BELT TENSION SENSOR CIRCUIT (SHORT)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK FRONT SEAT WIRE RH (SHORT)
OK -- Continue to next step.
6. CHECK DTC
(a) Connect the connectors to the occupant classification ECU and the seat belt tension sensor.
(b) Connect the cable to the negative (-) battery terminal.
(c) Turn the engine switch on (IG).
(d) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(e) Clear the DTCs stored in the center airbag sensor assembly DTC Check / Clear.
(f) Turn the engine switch off.
(g) Turn the engine switch on (IG).
(h) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1773 and B1776 are not output.
HINT: Codes other than B1773 and B1776 may be output at this time, but they are not related to this check.
NG -- INSPECT FRONT SEAT OUTER BELT ASSEMBLY RH
OK -- USE SIMULATION METHOD TO CHECK
7. INSPECT FRONT SEAT OUTER BELT ASSEMBLY RH
(a) Turn the engine switch off.
(b) Disconnect the cable from the negative (-) battery terminal.
(c) Replace the front seat outer belt assembly RH with a known good part Reading and Clearing Diagnostic Trouble Codes.
HINT: Perform an inspection using known good parts from another vehicle if possible.
(d) Connect the cable from the negative (-) battery terminal.
(e) Turn the engine switch on (IG).
(f) Clear the DTCs stored in the occupant classification ECU Removal.
(g) Clear the DTCs stored in the center airbag sensor assembly Reading and Clearing Diagnostic Trouble Codes.
(h) Turn the engine switch off.
(i) Turn the engine switch on (IG).
(j) Check for DTCs DTC Check / Clear.
OK:
DTC B1773 and B1776 are not output.
HINT: Codes other than B1773 and B1776 may be output at this time, but they are not related to this check.
NG -- REPLACE OCCUPANT CLASSIFICATION ECU
OK -- END
8. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Using the Techstream, save the ECU data from the ECU which has been installed on the vehicle Registration.
(d) Turn the engine switch off.
(e) Disconnect the cable from the negative (-) battery terminal.
(f) Replace the occupant classification ECU Removal.
(g) Connect the cable to the negative (-) battery terminal.
(h) Turn the engine switch on (IG).
(i) Using the Techstream, load the previous ECU data stored into the new ECU Registration.
(j) Turn the engine switch off.
(k) Turn the engine switch on (IG).
(l) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT: If the DTCs are not cleared at this time, past DTC will remain.
NEXT -- Continue to next step.
9. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END
10. CHECK FRONT SEAT WIRE RH (SHORT TO B+)
(a) Turn the engine switch off.
(b) Disconnect the cable from the negative (-) battery terminal.
(c) Disconnect the floor wire connector from the front seat wire RH.
(d) Connect the cable to the negative (-) battery terminal.
(e) Turn the engine switch on (IG).
(f) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
NG -- REPLACE FRONT SEAT WIRE RH
OK -- REPLACE FLOOR WIRE
11. CHECK FRONT SEAT WIRE RH (OPEN)
(a) Disconnect the floor wire connector from the front seat wire RH.
(b) Using SST, connect terminals 5 (BT) and 7 (GBT), and connect terminals 6 (VBT) and 7 (GBT) of connector C.
NOTICE: Do not forcibly insert SST into the terminals of the connector when connecting the wire.
SST: 09843-18040
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPLACE FRONT SEAT WIRE RH
OK -- REPLACE FLOOR WIRE
12. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)
(a) Disconnect the floor wire connector from the front seat wire RH.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPLACE FRONT SEAT WIRE RH
OK -- REPLACE FLOOR WIRE
13. CHECK FRONT SEAT WIRE RH (SHORT)
(a) Disconnect the floor wire connector from the front seat wire RH.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPLACE FRONT SEAT WIRE RH
OK -- REPLACE FLOOR WIRE