B1773
SUPPLEMENTAL RESTRAINT SYSTEM: OCCUPANT CLASSIFICATION SYSTEM: B1773,B1776: Belt Tension Sensor Circuit Malfunction
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 DTCs.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
* w/ Navigation System (for HDD):
After the power switch is turned off, the display and navigation module display (HDD navigation system) records various types of memory and settings. As a result, after turning the power switch off, be sure to wait for the time specified in the following table before disconnecting the cable from the negative (-) battery terminal.
Waiting Time before Disconnecting Cable from Negative (-) Battery Terminal:
* When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.
HINT
* If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger 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.
PROCEDURE
1. CHECK FOR DTC
(a) Turn the power switch ON (IG).
(b) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(c) Clear the DTCs stored in the center airbag sensor DTC Check / Clear.
(d) Turn the power switch OFF.
(e) Turn the power switch ON (IG).
(f) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTCs B1773 and B1776 are not output.
HINT
Codes other than DTCs B1773 and B1776 may be output at this time, but they are not related to this check.
NG -- CHECK CONNECTION OF CONNECTOR
OK -- USE SIMULATION METHOD TO CHECK Diagnosis System
2. CHECK CONNECTION OF CONNECTOR
(a) Turn the power switch OFF.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Check that the connectors are properly connected to the occupant classification ECU and the seat belt tension sensor.
OK:
Connectors are properly connected.
NG -- CONNECT CONNECTORS PROPERLY
OK -- Continue to next step.
3. CHECK CONNECTOR
(a) Disconnect the connectors from the occupant classification ECU and the belt tension sensor.
(b) Check that the connectors (on the center airbag sensor side and seat belt tension sensor side) are not damaged.
OK:
Connectors are not deformed or damaged.
HINT
If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.
NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
4. CHECK FRONT SEAT WIRE RH (SEAT BELT TENSION SENSOR - OCCUPANT CLASSIFICATION ECU)
(a) Connect the negative (-) terminal cable to the battery.
(b) Turn the power switch ON (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
(d) Turn the power switch OFF.
(e) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(f) Using 2 service wires, connect terminals 1 (GBT) and 3 (BT), and connect terminals 1 (GBT) and 2 (VBT) of connector C.
NOTICE:
Do not forcibly insert the service wires into the terminals of the connector when connecting the wire.
(g) Measure the resistance according to the value(s) in the table below.
Standard resistance:
(h) Disconnect the service wires from connector C.
(i) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
5. CHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and the seat belt tension sensor.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the power 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 DTC Check / Clear.
(f) Turn the power switch OFF.
(g) Turn the power switch ON (IG).
(h) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTCs B1773 and B1776 are not output.
HINT
Codes other than DTCs B1773 and B1776 may be output at this time, but they are not related to this check.
NG -- REPLACE FRONT SEAT OUTER BELT ASSEMBLY RH (SEAT BELT TENSION SENSOR)
OK -- USE SIMULATION METHOD TO CHECK Diagnosis System
6. REPLACE FRONT SEAT OUTER BELT ASSEMBLY RH (SEAT BELT TENSION SENSOR)
(a) Turn the power switch OFF.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the front seat outer belt Removal.
HINT
Perform the inspection using parts from a normal vehicle if possible.
(d) Connect the negative (-) terminal cable to the battery.
(e) Turn the power switch ON (IG).
(f) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(g) Clear the DTCs stored in the center airbag sensor DTC Check / Clear.
(h) Turn the power switch OFF.
(i) Turn the power switch ON (IG).
(j) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTCs B1773 and B1776 are not output.
HINT
Codes other than DTCs B1773 and B1776 may be output at this time, but they are not related to this check.
NG -- REPLACE FRONT SEAT SET (OCCUPANT CLASSIFICATION ECU)
OK -- END
7. REPLACE FRONT SEAT SET (OCCUPANT CLASSIFICATION ECU)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch ON (IG).
(c) Using the Techstream, save the ECU data from the ECU which was installed on the vehicle Registration.
(d) Turn the power switch OFF.
(e) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(f) Replace the front seat set (occupant classification ECU) Disassembly.
(g) Connect the negative (-) terminal cable to the battery.
(h) Turn the power switch ON (IG).
(i) Using the Techstream, load the previous ECU data stored in the Techstream into the new ECU Registration.
(j) Turn the power switch OFF.
(k) Turn the power switch ON (IG).
(l) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT
If DTCs are not cleared at this time, past DTCs will remain.
NEXT -- Continue to next step.
8. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END