B1774
SUPPLEMENTAL RESTRAINT SYSTEM: OCCUPANT CLASSIFICATION SYSTEM: B1774,B1775: Pressure Sensor Circuit Malfunction
B1775 - Pressure Sensor Power Source Circuit Malfunction
DESCRIPTION
The pressure sensor circuit consists of the occupant classification ECU and the occupant classification sensor.
The occupant classification sensor sends the pressure signal to the occupant classification ECU.
DTC B1774 and B1775 are recorded when a malfunction is detected in the pressure 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 B1774 and B1775 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 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 a problem, such as seat rail deformation. Hold the seat only as necessary.
* After performing the zero point calibration, check for DTCs to confirm that the calibration is completed normally. (If it fails, DTC B1797 will be output.)
PROCEDURE
1. CHECK DTC
(a) Turn the engine 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 assembly Reading and Clearing Diagnostic Trouble Codes.
(d) Turn the engine switch off.
(e) Turn the engine switch on (IG).
(f) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1774 and B1775 are not output.
HINT
Codes other than B1774 and B1775 may be output at this time, but they are not related to this check.
OK -- USE SIMULATION METHOD TO CHECK Diagnosis System
NG -- Continue to next step.
2. CHECK CONNECTION OF CONNECTORS
(a) Turn the engine 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 occupant classification sensor.
OK:
The connectors are properly connected.
NG -- CONNECT CONNECTORS PROPERLY, THEN GO TO STEP 1
OK -- Continue to next step.
3. CHECK CONNECTORS
(a) Disconnect the connectors from the occupant classification ECU and the occupant classification sensor.
(b) Check that the connectors (on the occupant classification ECU side and occupant classification sensor side) are not damaged.
OK:
The connectors are not deformed or damaged.
NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
4. CHECK FRONT SEAT WIRE RH (SHORT TO B+)
(a) Connect the negative (-) terminal cable to the battery.
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
5. CHECK FRONT SEAT WIRE RH (OPEN)
(a) Turn the engine switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Using a service wire, connect terminals 1 (GPS) and 3 (VPS), and connect terminals 2 (PS) and 3 (VPS) of connector C.
NOTICE:
Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.
(d) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
6. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)
(a) Disconnect the service wire from connector C.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
7. CHECK FRONT SEAT WIRE RH (SHORT)
(a) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
8. CHECK DTC
(a) Connect the connectors to the occupant classification ECU and the occupant classification sensor.
(b) Connect the negative (-) terminal cable to the battery.
(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 Reading and Clearing Diagnostic Trouble Codes.
(f) Turn the engine switch off.
(g) Turn the engine switch on (IG).
(h) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTCs B1774 and B1775 are not output.
HINT
Codes other than B1774 and B1775 may be output at this time, but they are not related to this check.
OK -- USE SIMULATION METHOD TO CHECK Diagnosis System
NG -- Continue to next step.
9. REPLACE OCCUPANT CLASSIFICATION SENSOR (FRONT SEAT CUSHION ASSEMBLY)
(a) Turn the engine switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the front seat cushion assembly (with occupant classification ECU and occupant classification sensor) 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 engine 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 assembly Reading and Clearing Diagnostic Trouble Codes.
(h) Turn the engine switch off.
(i) Turn the engine switch on (IG).
(j) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1774 and B1775 are not output.
HINT
Codes other than B1774 and B1775 may be output at this time, but they are not related to this check.
NEXT -- Continue to next step.
10. PERFORM ZERO POINT CALIBRATION
(a) Connect Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Using Techstream, perform the zero point calibration Initialization.
(d) Turn the engine switch off.
(e) Turn the engine switch on (IG).
(f) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT
If DTC is not cleared at this time, past DTC will remain.
NEXT -- Continue to next step.
11. CHECK DTC
HINT
Check that the zero point calibration is completed normally. If any of the following conditions is met, DTC B1797 will be output (Refer to INITIALIZATION: Initialization):
* Zero point calibration is performed when the conditions for the calibration are not satisfied.
* Zero point calibration has failed.
(a) Turn the engine 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 assembly Reading and Clearing Diagnostic Trouble Codes.
(d) Turn the engine switch off.
(e) Turn the engine switch on (IG).
(f) Check the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1797 is not output.
NG -- GO TO DTC B1797 B1797
OK -- Continue to next step.
12. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END