B1774
SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1774,B1775: Pressure Sensor 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 those DTCs.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT
- If troubleshooting (wire harness inspection) is difficult to perform, remove the passenger seat installation bolts to access the underside 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 and deform the seat rails. 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 CONNECTORS
(a) Turn the ignition 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 occupant classification 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 occupant classification sensor.
(e) 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 -- Continue to next step.
2. CHECK FRONT SEAT WIRE RH (SHORT TO B+)
(a) Connect the cable to the negative (-) battery terminal.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
3. CHECK FRONT SEAT WIRE RH (OPEN)
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal.
(c) Using SST, connect terminals 1 (GPS) and 3 (VPS), and connect terminals 2 (PS) and 3 (VPS) of connector C.
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 -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
4. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND)
(a) Disconnect SST from connector C.
(b) 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 FRONT SEAT WIRE RH (SHORT)
(a) 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.
6. CHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and the occupant classification sensor.
(b) Connect the cable to the negative (-) battery terminal.
(c) Turn the ignition switch to ON.
(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 ignition switch off.
(g) Turn the ignition switch to ON.
(h) Check for 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.
NG -- REPLACE OCCUPANT CLASSIFICATION SENSOR (FRONT SEAT CUSHION ASSEMBLY)
OK -- USE SIMULATION METHOD TO CHECK Diagnosis System
7. REPLACE OCCUPANT CLASSIFICATION SENSOR (FRONT SEAT CUSHION ASSEMBLY)
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal.
(c) Replace the front seat cushion assembly (with occupant classification ECU and occupant classification sensor) with a known good part Removal.
HINT
Perform an inspection using known good parts from another vehicle if possible.
(d) Connect the cable to the negative (-) battery terminal.
(e) Turn the ignition switch to ON.
(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 DTC Check / Clear.
(h) Turn the ignition switch off.
(i) Turn the ignition switch to ON.
(j) Check for 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.
8. PERFORM ZERO POINT CALIBRATION
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Using the Techstream, perform the zero point calibration Initialization.
(d) Turn the ignition switch off.
(e) Turn the ignition switch to ON.
(f) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT
If the DTCs are not cleared at this time, past DTCs will remain.
NEXT -- Continue to next step.
9. CHECK FOR DTC
HINT
Check that the zero point calibration is completed normally. If either 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 ignition switch to ON.
(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 DTC Check / Clear.
(d) Turn the ignition switch off.
(e) Turn the ignition switch to ON.
(f) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1797 is not output.
NG -- GO TO DTC B1797 B1797
OK -- Continue to next step.
10. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END