Page 1449 of 4323

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1247
1441 Author: Date:
2005 SEQUOIA (RM1146U)
DTC B1662/45 SRS Warning Light Circuit Malfunction
CIRCUIT DESCRIPTION
The SRS warning light circuit consists of the airbag sensor assembly and the combination meter.
When the airbag sensor assembly detects a malfunction in the SRS airbag system, the SRS warning light
comes on to inform the driver.
It also comes on when the power voltage drops, and automatically goes off in approximately 10 seconds
after the power voltage returns to normal (DTC is not stored).
The SRS warning light comes on for 6 seconds after the ignition switch is turned to the ON position and goes
off if the system is normal.
When an open circuit is detected, such as when the connector between the combination meter and the air-
bag sensor assembly is disconnected, the SRS warning light remains on even when approximately 6 se-
conds elapsed after the ignition switch is turned to the ON position.
DTC B1662/45 is recorded when a malfunction is detected in the SRS warning light circuit.
DTC No.DTC Detecting ConditionTrouble Area
B1662/45
The airbag sensor assembly receives an open circuit sig-
nal or a short circuit to ground signal in the SRS warning
light circuit for 2 seconds.
SRS warning light malfunction
Airbag sensor assembly malfunction
Combination meter (SRS warning light)
Airbag sensor assembly
Cowl wire
HINT:
When DTC B1662/45 and B1000/31 are output simultaneously, perform the troubleshooting for DTC
B1662/45 first.
DIDH3±01
Page 1450 of 4323
H23996
LA
A2014
ABR I18
Ignition SW
Combination Meter
BatteryIG2 A2021
E1 A2025
E2 A2026 B
W±B
W±B B±R
IG2 AM26 5 W±R
SRS B±Y
C5 29
C612 C6241D4
1A5 1A3 IGN1
1D6
1F9
101A6
1A8 Instrument Panel J/B
Engine Room J/B1H11
1J7
2C1
2D1AM2BR
W±B
W±B
J8
J/C A
A 4
5 B
BB±O
IEAirbag Sensor
Assembly
1C2
Instrument Panel J/B
F10
Fusible Link Block 1C3 D6
DLC3
114B10
4A20
4A10B±Y
B±Y
1F W±R Sub J/B No. 4 DI±1248
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1442 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
Page 1451 of 4323

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1249
1443 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
1 Check battery.
CHECK:
Measure the voltage of the battery.
OK:
Voltage: 11 to 14 V
NG Replace battery.
OK
2 Check connection of connectors.
PREPARATION:
(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.
CHECK:
Check that the connectors are properly connected to the airbag sensor assembly and combination meter.
OK:
The connectors are connected securely.
NG Connect connectors, then go to step 1.
OK
3 Check combination meter.
PREPARATION:
(a) Disconnect the connectors from the airbag sensor assembly.
(b) Connect the negative (±) terminal cable to the battery, and wait for at least 2 seconds.
CHECK:
Turn the ignition switch to the ON position, check the operation of the SRS warning light.
OK:
The SRS warning light comes on (goes off 6 seconds after the ignition switch is turned to the
ON position).
NG Go to combination meter system
(see page DI±1610).
OK
Page 1452 of 4323
H22564H23040I27704H23986
A Cowl Wire Combination
Meter
C5
A20
Airbag
Sensor
Assembly
B C D
C5±29LA
DI±1250
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1444 Author: Date:
2005 SEQUOIA (RM1146U)
4 Check cowl wire (airbag sensor assembly ± combination meter).
PREPARATION:
Disconnect the connector from the combination meter.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Tester ConnectionConditionSpecified Condition
A20±14 (LA) ± C5±29AlwaysBelow 1 W
A20±14 (LA) ±
Body groundAlways1 MW or higher
NG Repair or replace cowl wire.
OK
Replace airbag sensor assembly (see page RS±82).
Page 1453 of 4323

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1251
1445 Author: Date:
2005 SEQUOIA (RM1146U)
DTC B1771 Passenger Side Buckle Switch Circuit
Malfunction
CIRCUIT DESCRIPTION
The passenger side buckle switch circuit consists of the occupant classification ECU and the front seat inner
belt RH.
DTC B1771 is recorded when a malfunction is detected in the passenger side buckle switch circuit.
Troubleshoot DTC B1771 first when the DTC B1771 and B1795 are output simultaneously.
DTC No.DTC Detecting ConditionTrouble Area
B1771
The occupant classification ECU receives a line short
circuit signal, an open circuit signal, a short circuit to
ground signal or a short circuit to B+ signal in the passen-
ger side buckle switch circuit for 2 seconds.
Passenger side buckle switch malfunction
Occupant classification ECU malfunction
Front seat inner belt RH
Occupant classification ECU
Seat wire No. 1
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 B1771 is output, perform troubleshooting
for the DTC.
DIDH4±01
Page 1454 of 4323
H23244
Occupant Classification ECU
O6
O6 R B17
Buckle SW RH
L
129
5BSW
BGND DI±1252
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1446 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
Page 1455 of 4323

± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±1253
1447 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 B1771 is not output.
HINT:
Codes other than DTC B1771 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).
Page 1456 of 4323

H43103H43111H23819
Occupant
Classification ECU
BGND
BSW CB DA
Front Seat
Inner Belt RHO6
Seat Wire No. 1
DI±1254
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
1448 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check connection of connectors.
PREPARATION:
(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.
CHECK:
Check that the connectors are properly connected to the occupant classification ECU and the front seat inner
belt RH.
OK:
The connectors are connected securely.
NG Connect connectors, then go to step 1.
OK
3 Check seat wire No. 1 (short to B+).
PREPARATION:
(a) Disconnect the connectors from the occupant classifica-
tion ECU and the front seat inner belt RH.
(b) Connect the negative (±) terminal cable to the battery.
CHECK:
(a) Turn the ignition switch to the ON position.
(b) Measure the voltage according to the value(s) in the table
below.
OK:
Tester ConnectionConditionSpecified Condition
O6±9 (BSW) ±
Body groundIgnition switch ONBelow 1 V
O6±5 (BGND) ±
Body groundIgnition switch ONBelow 1 V
NG Repair or replace seat wire No. 1.
OK