Seat Belt Warning System (Diagnostics): Overview Lexus LX J200

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COMMUNICATION TABLE

SYSTEM DESCRIPTION

1. SEAT BELT WARNING SYSTEM DESCRIPTION If a seat belt is not fastened, this system flashes the seat belt warning light or sounds the seat belt warning buzzer as a reminder. Driver side seat belt warning light: When the driver seat belt is not fastened with the engine switch on (IG), the driver side seat belt warning light on the combination meter comes on to inform the driver. The center airbag sensor detects the driver seat belt status and sends signals to the combination meter using the CAN. Front passenger side seat belt warning light: When the passenger seat belt is not fastened with the engine switch on (IG) and the passenger seat occupied, the passenger side seat belt warning light on the display and navigation module display*1 (multi-display*2) blinks. The occupant classification ECU detects the front passenger side seat belt status. HINT: *1: w/ Navigation System *2: w/o Navigation System Seat belt warning buzzer: When the vehicle is driven at approximately 20 km/h (12.5 mph) or more while the driver or front passenger seat belt is not fastened, the seat belt warning buzzer in the combination meter sounds at an interval of 1.2 seconds for 30 seconds.
2. FUNCTION OF MAIN COMPONENT The following functions are available. Component Function Front seat inner belt LH (driver side buckle switch) Informs center airbag sensor of driver seat belt condition (fastened or unfastened) Front seat inner belt RH (passenger side buckle switch) Informs center airbag sensor of front passenger seat belt condition (fastened or unfastened) Occupant detection sensor Informs center airbag sensor of front passenger seat condition (occupied or unoccupied) Driver side seat belt warning light If driver seat belt is unfastened and engine switch is on (IG), combination meter flashes seat belt warning light of combination meter as reminder Front passenger side seat belt warning light When front passenger seat is occupied and engine switch is on (IG), if passenger seat belt is unfastened, combination meter flashes seat belt warning light of multi-display as reminder Seat belt warning buzzer If driver or passenger seat belt is unfastened and engine switch is on (IG), combination meter sounds buzzer as reminder
3. SYSTEM OPERATION Driver side seat belt warning light When the driver seat belt is not fastened with the engine switch on (IG), the driver side seat belt warning light on the combination meter comes on to inform the driver. The center airbag sensor detects the driver seat belt status and sends signals to the combination meter using CAN. Front passenger side seat belt warning light When the passenger seat belt is not fastened with the engine switch on (IG) and the passenger seat occupied, check that the front passenger side seat belt warning light on the multi-display blinks. The occupant classification ECU detects the front passenger side seat belt status.

OPERATION CHECK

1. INSPECT DRIVER SIDE SEAT BELT WARNING LIGHT Turn the engine switch on (IG). When the driver seat belt is not fastened, check that the driver side seat belt warning light on the combination meter blinks. When the driver seat belt is fastened, check that the driver side seat belt warning light on the combination meter is off.
2. INSPECT FRONT PASSENGER SIDE SEAT BELT WARNING LIGHT Turn the engine switch on (IG). When the front passenger side seat belt is not fastened with the passenger seat occupied, check that the front passenger side seat belt warning light on the multi-display blinks. When the front passenger seat belt is fastened with the passenger seat occupied, check that the front passenger side seat belt warning light on the multi-display is off.
3. INSPECT SEAT BELT WARNING BUZZER HINT: If the buzzer does not sound, the buzzer cancel setting may be set to ON. Refer to «CUSTOMIZE PARAMETERS». Lift up the vehicle using a swing arm type lift. Refer to «VEHICLE LIFT AND SUPPORT LOCATIONS». Turn the engine switch on (IG). Place a weight of 20 kg (44.0 lb) on the front passenger seat. NOTE: Do not allow the weight to come into contact with the seatback when placing it on the seat cushion. Place the weight on the seat cushion. When the vehicle is driven at approximately 20 km/h (12.5 mph) or more while the driver or front passenger seat belt is not fastened, check that the buzzer in the combination meter sounds at an interval of 1.2 seconds for 30 seconds. Check that the buzzer sounds at an interval of 0.4 seconds for 90 seconds. Check that the buzzer stops 2 minutes after the buzzer starts sounding. After the buzzer has stopped, turn the engine switch off and then start the engine again. Drive the vehicle at approximately 20 km/h (12.5 mph) or more while the driver or front passenger seat belt is not fastened, and then check that the buzzer sounds again. After the buzzer has stopped, fasten the driver and front passenger seat belts. Drive the vehicle at approximately 20 km/h (12.5 mph) or more and unfasten the driver or front passenger seat belt, and then check that the buzzer sounds again. After the buzzer has stopped, move the shift lever to R, and then move it to D. Drive the vehicle at approximately 20 km/h (12.5 mph) or more, and then check that the buzzer sounds again.

DESCRIPTION

When the engine switch is on (IG), the center airbag sensor transmits front seat inner belt state signals to the combination meter through the CAN. If the driver seat belt is not fastened, the combination meter blinks the driver side seat belt warning light. If the seat belt is fastened, the warning light turns off.

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The combination meter detects the state of the front seat inner belt RH when the front passenger seat is occupied with the engine switch on (IG). If the front passenger seat belt is not fastened, the front passenger side seat belt warning light on the display and navigation module display*1 (multi-display*2) blinks. If the seat belt is fastened, the warning light turns off.

*1: w/ Navigation System

*2: w/o Navigation System

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1. CHECK FOR DTC Check for DTCs. RESULT Result Proceed to DTC is not output A CAN communication system DTC is output B Airbag system DTC is output C Occupant classification system DTC is output D D --> See step 10 C --> See step 9 B --> See step 8 A: Go to next step
2. PERFORM ACTIVE TEST USING TECHSTREAM Operate the Techstream according to the steps on the display and select "Active Test". COMBINATION METER Item Test Part Control Range Diagnostic Note Front Passenger Side Seat Belt Front passenger side seat belt warning light ON or OFF Confirm that the Vehicle is Stopped and Engine Idling OK Front passenger side seat belt warning light condition can be switched by Active Test NG --> See step 6 OK: Go to next step
3. INSPECT FUSE (ECU-IG No. 1) Disconnect the ECU-IG No. 1 fuse from the cowl side junction block RH. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition ECU-IG No. 1 fuse Always Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (MULTI-DISPLAY - COMBINATION METER, BATTERY AND BODY GROUND) Disconnect the F28 display connector. Disconnect the E77 meter connector. Measure the resistance and voltage according to the value(s) in the tables below. Standard Resistance Tester Connection Condition Specified Condition F28-21 (PBEW) - E77-39 (WRNP) Always Below 1 ohms F28-10 (GND1) - Body ground F28-21 (PBEW) or E77-39 (WRNP) - Body ground Always 10 kohms or higher Standard Voltage Tester Connection Switch Condition Specified Condition F28-3 (IG) - Body ground Engine switch on (IG) 11 to 14 V NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
5. CHECK DISPLAY AND NAVIGATION MODULE DISPLAY*1 (MULTI-DISPLAY*2) Disconnect the F28 display connector. Measure the voltage according to value(s) in the table below. OK Measurement Connection Specified Condition Battery positive (+) --> F28-3 (IG) Battery negative (-) --> F28-21 (PBEW) Battery negative (-) --> F28-10 (GND1) Front passenger side seat belt warning light on RESULT Result Proceed to OK A NG (w/ Navigation System) B NG (w/o Navigation System) C C --> See step 13 B --> REPLACE DISPLAY AND NAVIGATION MODULE DISPLAY A --> See step 11
6. REPLACE FRONT SEAT INNER BELT ASSEMBLY RH Temporarily replace the front seat inner belt RH with a new one. Refer to «REMOVAL». NEXT: Go to next step
7. CHECK FRONT PASSENGER SIDE SEAT BELT WARNING LIGHT Check the front passenger side seat belt warning light function. Refer to «OPERATION CHECK». OK Front passenger side seat belt warning light operates normally. NG --> See step 12 OK --> END (FRONT SEAT INNER BELT RH IS DEFECTIVE)
8. Go to CAN COMMUNICATION SYSTEM. Refer to «DIAGNOSTIC TROUBLE CODE CHART»
9. Go to AIRBAG SYSTEM. Refer to «DIAGNOSTIC TROUBLE CODE CHART»
10. Go to OCCUPANT CLASSIFICATION SYSTEM. Refer to «DIAGNOSTIC TROUBLE CODE CHART»
11. REPLACE COMBINATION METER. Refer to «REMOVAL»
12. REPLACE COMBINATION METER. Refer to «REMOVAL»
13. REPLACE MULTI-DISPLAY. Refer to «REMOVAL»(/lexus/lx/j200-2007-2012/remont/entertainment-systems/#audio-video-multi-display-service-information)

See also:
• REMOVAL