Toyota Tundra. Manual — part 2639

Fig. 219: Identifying Center Airbag Sensor Assembly Communication Circuit Malfunction Wiring
Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

INSPECTION PROCEDURE

HINT:



If troubleshooting (wire harness inspection) is difficult to perform, remove the front RH 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 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:

NOTE:

After the ignition switch is turned OFF, the navigation system requires
approximately 90 seconds to record various types of memory and settings. As a
result, after turning the ignition switch OFF, wait 90 seconds or more before
disconnecting the cable from the negative (-) battery terminal.

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra



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 B1790 is not output.

HINT:

DTCs other than DTC B1790 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 center

airbag sensor.

OK: Connectors are properly connected.

NG: CONNECT CONNECTOR

OK: Go to next step

3. CHECK CONNECTOR

a. Check that the connectors (on the center airbag sensor side and occupant classification ECU side)

are not damaged (see ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).

OK: Connectors are not deformed or damaged.

Result

RESULT TABLE

Result

Proceed to

Connectors are not deformed or damaged
(for Power seat)

A

Connectors are not deformed or damaged

B

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

B: Go to step 11

C: REPLACE HARNESS OR CONNECTOR

A: Go to next step

4. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT

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

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

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

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION TABLE

d. Turn the ignition switch OFF.

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

f. Using a service wire, connect terminals 12 (FSP+) and 13 (FSP-) of connector B.

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

(for Manual seat)
Connectors are deformed or damaged

C

Tester Connection

Switch Condition Specified Condition

Y2-8 (FSR+) - Body ground

Ignition switch ON

Below 1 V

Y2-4 (FSR-) - Body ground

NOTE:

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

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

Fig. 220: Checking Occupant Classification System Circuit
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION TABLE

h. Disconnect the service wire from connector B.

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

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION TABLE

Tester Connection

Condition Specified Condition

Y2-8 (FSR+) - Y2-4 (FSR-) Always

Below 1 ohms

Tester Connection

Condition Specified Condition

Y2-8 (FSR+) - Y2-4 (FSR-)

Always

1 Mohms or higher

Y2-8 (FSR+) - Body ground

Y2-4 (FSR-) - Body ground

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra