Toyota Tundra. Manual — part 2638

DTCs other than DTC B1788 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. PERFORM ZERO POINT CALIBRATION

a. Connect the Techstream to the DLC3.

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

c. Using the Techstream, perform the zero point calibration (see INITIALIZATION ).

NG: Go to step 5

OK: Go to next step

3. PERFORM SENSITIVITY CHECK

a. Using the Techstream, perform the sensitivity check (see INITIALIZATION ).

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

NG: Go to step 5

OK: Go to next step

4. CHECK FOR DTC

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

b. Clear the DTCs stored in the center airbag sensor (see DTC CHECK/CLEAR ).

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 B1788 is not output.

HINT:

DTCs other than DTC B1788 may be output at this time, but they are not related to this check.

NG: Go to step 5

OK: END

5. REPLACE FRONT SEAT FRAME WITH ADJUSTER ASSEMBLY RH

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

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 front seat frame with adjuster RH (see FRONT POWER SEAT MOTOR

ASSEMBLY (FOR POWER SEAT) ).

HINT:

Perform the inspection using parts from a normal vehicle when possible.

6. PERFORM ZERO POINT CALIBRATION

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

b. Connect the Techstream to the DLC3.

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

d. Using the Techstream, perform the zero point calibration (see INITIALIZATION ).

NG: Go to step 9

OK: Go to next step

7. PERFORM SENSITIVITY CHECK

a. Using the Techstream, perform the sensitivity check (see INITIALIZATION ).

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

NG: Go to step 9

OK: Go to next step

8. CHECK FOR DTC

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

RH.

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

c. 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.

d. Turn the ignition switch OFF.

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

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

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

CHECK/CLEAR ).

OK: DTC B1788 is not output.

HINT:

DTCs other than DTC B1788 may be output at this time, but they are not related to this check.

NG: Go to step 9

OK: END

9. 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) )

HINT:

Perform the inspection using parts from a normal vehicle when possible.

10. PERFORM ZERO POINT CALIBRATION

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

b. Connect the Techstream to the DLC3.

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

d. Using the Techstream, perform the zero point calibration (see INITIALIZATION ).

11. PERFORM SENSITIVITY CHECK

a. Using the Techstream, perform the sensitivity check (see INITIALIZATION ).

Standard range:

27 to 33 kg (59.5 to 72.8 lb)

NEXT: END

DTC B1790: CENTER AIRBAG SENSOR ASSEMBLY COMMUNICATION CIRCUIT
MALFUNCTION

DESCRIPTION

The center airbag sensor communication circuit consists of the occupant classification ECU and the center

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra

airbag sensor.

DTC B1790 is set when a malfunction is detected in the center airbag sensor communication circuit.

DTC TROUBLE DETECTION CONDITION TABLE

HINT:



When DTC B1630/32 is detected as a result of troubleshooting the airbag system, perform
troubleshooting for DTC B1790 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

DTC

Code

DTC Detection Condition

Trouble Area

B1790

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 center airbag sensor communication circuit for 2
seconds



Center airbag sensor malfunction



Occupant classification ECU malfunction



No. 2 floor wire



Front seat wire
RH



Occupant
classification
ECU



Center airbag
sensor

2009 Toyota Tundra

2009 RESTRAINTS Supplemental Restraint System - Tundra