Dtc B1793 Occupant Classification Sensor Power Supply Circuit Malfunction
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
CHECK FOR DTC
CHECK CONNECTION OF CONNECTOR
CHECK CONNECTOR
CHECK FRONT SEAT WIRE RH
CHECK FOR DTC
REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY
PERFORM ZERO POINT CALIBRATION AND SENSITIVITY CHECK
DTC B1793 Occupant Classification Sensor Power Supply Circuit Malfunction |
DESCRIPTION
The occupant classification sensor power supply circuit consists of the occupant classification ECU and the occupant classification sensors.DTC B1793 is stored when a malfunction is detected in the occupant classification sensor power supply circuit.DTC Code
| DTC Detection Condition
| Trouble Area
|
B1793
| One of following conditions is met:
- Occupant classification ECU receives line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in occupant classification sensor power supply circuit for 2 seconds
- Open circuit in occupant classification sensor wire harness
- Occupant classification ECU malfunction
| - Separate type front seat cushion spring assembly (Rear occupant classification sensors)
- Front seat wire RH
|
- HINT:
- When DTC B1650/32 is detected as a result of troubleshooting the airbag system, perform troubleshooting for DTC B1793 of the occupant classification system.
- Use the Techstream to check for DTCs of the occupant classification ECU, otherwise the DTCs cannot be read.
WIRING DIAGRAM
INSPECTION PROCEDURE
- HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front seat assembly RH 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 problems, such as seat rail deformation. Hold the seat up only for as long as necessary.
Turn the ignition switch to ON, and wait for at least 60 seconds.
Clear any DTCs stored in the memory (YARIS_NCP93 RM0000010VK072X.html).
- HINT:
- First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assembly.
- Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
Turn the ignition switch off.
Turn the ignition switch to ON, and wait for at least 60 seconds.
Using the Techstream, check for DTCs of the occupant classification ECU (YARIS_NCP93 RM0000010VK072X.html).
- OK:
- DTC B1793 is not output.
- HINT:
- DTCs other than DTC B1793 may be output at this time, but they are not related to this check.
| 2.CHECK CONNECTION OF CONNECTOR |
Turn the ignition switch off.
Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
Check that the connectors are properly connected to the occupant classification ECU and the occupant classification sensors.
- OK:
- Connectors are properly connected.
| | CONNECT CONNECTORS PROPERLY |
|
|
Check that the connectors (on the occupant classification ECU side and the occupant classification sensors side) are not damaged.
- OK:
- Connectors are not deformed or damaged.
| 4.CHECK FRONT SEAT WIRE RH |
Disconnect the connectors from the occupant classification ECU and the 2 occupant classification sensors.
Text in Illustration*1
| Occupant Classification Sensor
| *2
| Occupant Classification ECU
|
*3
| Front Seat Wire RH
| -
| -
|
*a
| Front view of wire harness connector
(to Occupant Classification ECU)
| *b
| Front view of wire harness connector
(to Rear Occupant Classification Sensor LH)
|
*c
| Front view of wire harness connector
(to Rear Occupant Classification Sensor RH)
| *d
| Connector B
|
*e
| Connector C
| -
| -
|
Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
Turn the ignition switch to ON, and wait for at least 60 seconds.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
Tester Connection
| Switch Condition
| Specified Condition
|
X3-1 - Body ground
| Ignition switch ON
| Below 1 V
|
X3-2 - Body ground
|
Turn the ignition switch off.
Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
Tester Connection
| Condition
| Specified Condition
|
X3-1 - X2-1
| Always
| Below 1 Ω
|
X3-2 - X1-1
|
X3-1 - Body ground
| Always
| 1 MΩ or higher
|
X3-2 - Body ground
|
X3-1 - X3-2
|
Connect the connectors to the occupant classification ECU and the 2 occupant classification sensors.
Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
Turn the ignition switch to ON, and wait for at least 60 seconds.
Clear any DTCs stored in the memory (YARIS_NCP93 RM0000010VK072X.html).
- HINT:
- First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assembly.
- Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
Turn the ignition switch off.
Turn the ignition switch to ON, and wait for at least 60 seconds.
Using the Techstream, check for DTCs of the occupant classification ECU (YARIS_NCP93 RM0000010VK072X.html).
- OK:
- DTC B1793 is not output.
- HINT:
- DTCs other than DTC B1793 may be output at this time, but they are not related to this check.
| 6.REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY |
Turn the ignition switch off.
Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
Replace the separate type front seat cushion spring assembly (YARIS_NCP93 RM000001WB001FX.html).
- HINT:
- Perform the inspection using parts from a normal vehicle when possible.
| 7.PERFORM ZERO POINT CALIBRATION AND SENSITIVITY CHECK |
Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Using the Techstream, perform Zero Point Calibration and Sensitivity Check (YARIS_NCP93 RM0000010VN073X.html).
