2001 TOYOTA SEQUOIA Page 18

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1315
1509 Author: Date:
2005 SEQUOIA (RM1146U)
DTC B1788 Occupant Classification Sensor Rear RH
Collision Detection
CIRCUIT DESCRIPTION
DTC B1788 is output when the occupant classification ECU receives a collision detection signal sent by the
occupant classification sensor rear RH if an accident occurs.
DTC B1788 is also output when the front seat assembly RH is subjected to a strong impact, even if an actual
accident does not occur.
However, when the occupant classification ECU outputs a collision detection signal, even if the vehicle is
not in a collision, DTC B1788 can be cleared by ºZero point calibrationº and ºSensitivity checkº.
Therefore, if DTC B1788 is output, first perform ºZero point calibrationº and ºSensitivity checkº.
DTC No.DTC Detecting ConditionTrouble Area
B1788

Front seat assembly RH malfunction

Occupant classification ECU malfunction

Occupant classification sensor rear RH detects heavy
load.
Front seat assembly RH
(Occupant classification sensor rear RH)

Occupant classification ECU
HINT:
When DTC B1650/32 is detected as a result of troubleshooting for the supplemental restraint system, check
the DTCs stored in the occupant classification ECU. When DTC B1788 is output, perform troubleshooting
for the DTC.
WIRING DIAGRAM
See page DI±1290.
INSPECTION PROCEDURE
1 Perform zero point calibration.
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Using the hand±held tester, perform ºZero point calibrationº (see page DI±1128).
OK:
The ºCOMPLETEDº is displayed.
NG Go to step 4.
OK
DIDHC±01

DI±1316
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1510 Author: Date:
2005 SEQUOIA (RM1146U)
2 Perform sensitivity check.
Using the hand±held tester, perform ºSensitivity checkº (see page DI±1128).
OK:
Standard value: 27 to 33 kg (59.52 to 72.75 lb)
NG Go to step 4.
OK
3 Check DTC.
CHECK:
(a) Turn the ignition switch to the ON position.
(b) Clear the DTCs stored in memory (see page DI±1147).
HINT:
First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assembly.
(c) Turn the ignition switch to the LOCK position.
(d) Turn the ignition switch to the ON position.
(e) Using the hand±held tester, check the DTCs of the occupant classification ECU (see page DI±1147).
OK:
DTC B1788 is not output.
HINT:
Codes other than DTC B1788 may be output at this time, but they are not related to this check.
NG Go to step 4.
OK
END

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1317
1511 Author: Date:
2005 SEQUOIA (RM1146U)
4 Replace front seat assembly RH.
(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (±) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the front seat assembly RH (see page BO±112, BO±126).
HINT:
Perform the inspection using parts from a normal vehicle if possible.
NEXT
5 Perform zero point calibration.
(a) Connect the negative (±) terminal cable to the battery.
(b) Connect the hand±held tester to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the hand±held tester, perform ºZero point calibrationº (see page DI±1128).
OK:
The ºCOMPLETEDº is displayed.
NG Go to step 8.
OK
6 Perform sensitivity check.
Using the hand±held tester, perform ºSensitivity checkº (see page DI±1128).
OK:
Standard value: 27 to 33 kg (59.52 to 72.75 lb)
NG Go to step 8.
OK

DI±1318
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1512 Author: Date:
2005 SEQUOIA (RM1146U)
7 Check DTC.
CHECK:
(a) Turn the ignition switch to the ON position.
(b) Clear the DTCs stored in memory (see page DI±1147).
HINT:
First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assembly.
(c) Turn the ignition switch to the LOCK position.
(d) Turn the ignition switch to the ON position.
(e) Using the hand±held tester, check the DTCs of the occupant classification ECU (see page DI±1147).
OK:
DTC B1788 is not output.
HINT:
Codes other than DTC B1788 may be output at this time, but they are not related to this check.
NG Go to step 8.
OK
END

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1319
1513 Author: Date:
2005 SEQUOIA (RM1146U)
8 Replace occupant classification ECU.
(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (±) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the occupant classification ECU (see page RS±111).
NEXT
9 Perform zero point calibration.
(a) Connect the negative (±) terminal cable to the battery.
(b) Connect the hand±held tester to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the hand±held tester, perform ºZero point calibrationº (see page DI±1128).
OK:
The ºCOMPLETEDº is displayed.
NEXT
10 Perform sensitivity check.
Using the hand±held tester, perform ºSensitivity checkº (see page DI±1128).
OK:
Standard value: 27 to 33 kg (59.52 to 72.75 lb)
NEXT
END

DI±1322
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1516 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:

If troubleshooting (wire harness inspection) is difficult to perform, remove the passenger seat installa-
tion bolts to see the under surface of 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 a problem, such as seat rail deformation. Hold the seat only as necessary.
1 Check DTC.
CHECK:
(a) Turn the ignition switch to the ON position.
(b) Clear the DTCs stored in memory (see page DI±1147).
HINT:
First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assembly.
(c) Turn the ignition switch to the LOCK position.
(d) Turn the ignition switch to the ON position.
(e) Using the hand±held tester, check the DTCs of the occupant classification ECU (see page DI±1147).
OK:
DTC B1790 is not output.
HINT:
Codes other than DTC B1790 may be output at this time, but they are not related to this check.
NG Go to step 2.
OK
From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use the simulation method to check (see page DI±1137).

DI±1326
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1520 Author: Date:
2005 SEQUOIA (RM1146U)
8 Check DTC.
PREPARATION:
(a) Connect the connectors to the occupant classification ECU and the airbag sensor assembly.
(b) Connect the negative (±) terminal cable to the battery.
CHECK:
(a) Turn the ignition switch to the ON position.
(b) Clear the DTCs stored in memory (see page DI±1147).
HINT:
First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assembly.
(c) Turn the ignition switch to the LOCK position.
(d) Turn the ignition switch to the ON position.
(e) Using the hand±held tester, check the DTCs of the occupant classification ECU (see page DI±1147).
OK:
DTC B1790 is not output.
HINT:
Codes other than DTC B1790 may be output at this time, but they are not related to this check.
NG Go to step 9.
OK
From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use the simulation method to check (see page DI±1137).

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1327
1521 Author: Date:
2005 SEQUOIA (RM1146U)
9 Replace occupant classification ECU.
(a) Turn the ignition switch to the LOCK position.
(b) Disconnect the negative (±) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the occupant classification ECU (see page RS±111).
HINT:
Perform the inspection using parts from a normal vehicle if possible.
NEXT
10 Perform zero point calibration.
(a) Connect the negative (±) terminal cable to the battery.
(b) Connect the hand±held tester to the DLC3.
(c) Turn the ignition switch to the ON position.
(d) Using the hand±held tester, perform ºZero point calibrationº (see page DI±1128).
OK:
The ºCOMPLETEDº is displayed.
NEXT
11 Perform sensitivity check.
Using the hand±held tester, perform ºSensitivity checkº (see page DI±1128).
OK:
Standard value: 27 to 33 kg (59.52 to 72.75 lb)
NEXT