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 detection sensor.
The occupant detection 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 DTCs.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
* w/ Navigation System (for HDD):
After the engine 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 engine 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 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 FOR 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 Reading and Clearing Diagnostic Trouble Codes.
(d) Turn the engine switch off.
(e) Turn the engine switch on (IG).
(f) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTCs B1774 and B1775 are not output.
HINT
Codes other than DTCs B1774 and B1775 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 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 detection 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 occupant detection sensor.
(b) Check that the connectors (on the center airbag sensor and occupant detection sensor side) are not damaged.
OK:
Connectors are not deformed or damaged.
NG -- REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
4. CHECK FRONT SEAT WIRE RH
(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:
(d) Turn the engine 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 3 (VPS) and 1 (GPS), and connect terminals 2 (PS) and 1 (GPS) 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 occupant detection 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 Reading and Clearing Diagnostic Trouble Codes.
(f) Turn the engine switch off.
(g) Turn the engine switch on (IG).
(h) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTCs B1774 and B1775 are not output.
HINT
Codes other than DTCs B1774 and B1775 may be output at this time, but they are not related to this check.
NG -- REPLACE FRONT SEAT SET (OCCUPANT DETECTION SENSOR)
OK -- USE SIMULATION METHOD TO CHECK Diagnosis System
6. REPLACE FRONT SEAT SET (OCCUPANT DETECTION SENSOR)
(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 set (with occupant classification ECU and occupant detection sensor) Disassembly.
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 Data List / Active Test
(h) Turn the engine switch off.
(i) Turn the engine switch on (IG).
(j) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTCs B1774 and B1775 are not output.
HINT
Codes other than DTCs B1774 and B1775 may be output at this time, but they are not related to this check.
NEXT -- Continue to next step.
7. PERFORM ZERO POINT CALIBRATION
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Using the Techstream, perform 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 DTCs are not cleared at this time, past DTCs will remain.
NEXT -- Continue to next step.
8. CHECK FOR DTC
HINT
Check that the zero point calibration is completed normally. If one 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 Reading and Clearing Diagnostic Trouble Codes.
(d) Turn the engine switch off.
(e) Turn the engine switch on (IG).
(f) Check for 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.
9. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END