Toyota Tundra. Manual — part 2629

HINT:



If troubleshooting (wire harness inspection) is difficult to perform, remove the front seat 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.

1. CHECK FOR DTC

a. Turn the ignition switch ON, and wait for at least 60 seconds.

b. Clear any DTCs stored in the memory (see DTC CHECK/CLEAR ).

HINT:



First clear DTCs stored in the occupant classification ECU and then in the center airbag
sensor.



Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the
DTCs cannot be cleared.

c. Turn the ignition switch OFF.

d. Turn the ignition switch ON, and wait for at least 60 seconds.

e. Using the Techstream, check for DTCs of the occupant classification ECU (see DTC

CHECK/CLEAR ).

OK: DTC B1781 is not output.

HINT:

DTCs other than DTC B1781 may be output at this time, but they are not related to this check.

NG: Go to step 2

OK: USE SIMULATION METHOD TO CHECK (See DIAGNOSIS SYSTEM )

2. CHECK CONNECTION OF CONNECTOR

a. Turn the ignition 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 front

occupant detection sensor RH.

OK: Connectors are properly connected.

NG: CONNECT CONNECTOR

disconnecting the cable from the negative (-) battery terminal.

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

OK: Go to next step

3. CHECK CONNECTOR

a. Check that the connectors (on the occupant classification ECU side and front occupant detection

sensor RH side) are not damaged (see ELECTRONIC CIRCUIT INSPECTION
PROCEDURE ).

OK: Connectors are not deformed or damaged.

NG: REPLACE FRONT SEAT WIRE RH

OK: Go to next step

4. CHECK FRONT SEAT WIRE RH

a. Disconnect the connectors from the occupant classification ECU and the front occupant detection

sensor RH.

b. Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.

c. Turn the ignition switch ON, and wait for at least 60 seconds.

d. Measure the voltage according to the value(s) in the table below.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION TABLE

e. Turn the ignition switch OFF.

f. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.

g. Using service wires, connect terminals 1 (SVC2) and 3 (SGD2), and connect terminals 2 (SIG2)

and 3 (SGD2) of connector C.

h. Measure the resistance according to the value(s) in the table below.

Tester Connection

Switch Condition Specified Condition

Y1-2 (SGD2) - Body ground

Ignition switch ON

Below 1 V

Y1-8 (SIG2) - Body ground

Y1-12 (SVC2) - Body ground

NOTE:

Do not forcibly insert the service wires into the terminals of the
connector.

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

Fig. 210: Identifying Front Seat Wire RH
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION TABLE

i. Disconnect the service wires from connector C.

j. Measure the resistance according to the value(s) in the table below.

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION TABLE

Tester Connection

Condition Specified Condition

Y1-8 (SIG2) - Y1-2 (SGD2)

Always

Below 1 ohms

Y1-12 (SVC2) - Y1-2 (SGD2)

Tester Connection

Condition Specified Condition

Y1-8 (SIG2) - Y1-2 (SGD2)

Always

1 Mohms or higher

Y1-12 (SVC2) - Y1-2 (SGD2)

Y1-8 (SIG2) - Y1-12 (SVC2)

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

NG: REPLACE FRONT SEAT WIRE RH

OK: Go to next step

5. CHECK FOR DTC

a. Connect the connectors to the occupant classification ECU and the front occupant detection sensor

RH.

b. Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.

c. Turn the ignition switch ON, and wait for at least 60 seconds.

d. Clear any DTCs stored in the memory (see DTC CHECK/CLEAR ).

HINT:



First clear DTCs stored in the occupant classification ECU and then in the center airbag
sensor.



Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the
DTCs cannot be cleared.

e. Turn the ignition switch OFF.

f. Turn the ignition switch ON, and wait for at least 60 seconds.

g. Using the Techstream, check for DTCs of the occupant classification ECU (see DTC

CHECK/CLEAR ).

OK: DTC B1781 is not output.

HINT:

DTCs other than DTC B1781 may be output at this time, but they are not related to this check.

NG: Go to step 6

OK: USE SIMULATION METHOD TO CHECK (See DIAGNOSIS SYSTEM )

6. REPLACE OCCUPANT CLASSIFICATION ECU

a. Turn the ignition switch OFF.

b. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.

c. Replace the occupant classification ECU.



for Manual Seat (see FRONT SEAT ASSEMBLY (FOR FOLD DOWN SEAT TYPE) )



for Power Seat (see FRONT SEAT ASSEMBLY (FOR POWER SEAT) )

Y1-2 (SGD2) - Body ground

Y1-8 (SIG2) - Body ground

Y1-12 (SVC2) - Body ground

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra