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05-1078
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM 05IX3-04
DTC B1790 AIRBAG SENSOR ASSY CENTER
COMMUNICATION CIRCUIT MALFUNCTION
CIRCUIT DESCRIPTION
The airbag sensor assy center communication circuit consists of the occupant classification ECU and the
airbag sensor assy center.
DTC B1790 is recorded when a malfunction is detected in the airbag sensor assy center communication
circuit.
DTC No. DTC Detecting Condition Trouble Area
S The occupant classification ECU receives a line short
circuit signal, an open circuit signal, a short circuit to S Occupant classification ECU
ground signal or a short circuit to B+ signal in the airbag S Airbag sensor assy center
B1790
sensor assy center communication circuit for 2 seconds. S Floor wire No.2
S Airbag sensor assy center malfunction S Front seat wire RH
S Occupant classification ECU malfunction
HINT:
When DTC B1150/23 is detected as a result of troubleshooting for the supplemental restraint system, per-
form troubleshooting for DTC B1790 of the occupant classification system.
WIRING DIAGRAM
Occupant Airbag Sensor
Classification ECU Assy Center
8 3 1 3
G-R G-R
FSR+ O3 BO1 A22 A22 FSR+
(*3) (*3)
(*1) (*2)
3
G-R G-R
BM1
(*4) (*4)
4 5 2 10
FSR- G-B G-B
O3 BO1 A22 A22 FSR-
(*3) (*3)
(*1) (*2)
2
G-B G-B
BM1
(*4) (*4)
*1: w/ Side Airbag
*2: w/o Side Airbag
*3: w/ Power Seat
*4: w/o Power Seat
H45983
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1261
05-1079
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM
INSPECTION PROCEDURE
HINT:
S If troubleshooting (wire harness inspection) is difficult to perform, remove the front RH seat assy instal-
lation bolts to see the under surface of seat cushion.
S 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
(a) Turn the ignition switch to the ON position.
(b) Clear the DTCs stored in memory (see page 05-777 ).
HINT:
First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assy center.
(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 (see page 05-777 ).
OK:
DTC B1790 is not output.
HINT:
Codes other than code 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 PAGE 05-770 )
2 CHECK CONNECTION OF CONNECTORS
(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) Check that the connectors are properly connected to the occupant classification ECU and the airbag
sensor assy center.
OK:
The connectors are connected.
NG CONNECT CONNECTORS, THEN GO TO STEP
1
OK
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1262
05-1080
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM
3 CHECK AIRBAG SENSOR ASSY CENTER COMMUNICATION CIRCUIT(TO B+)
(a) Connect the negative (-) terminal cable to the battery,
Occupant and wait for at least 2 seconds.
Airbag
Classification ECU
Sensor (b) Turn the ignition switch to the ON position.
Assy (c) Measure the voltage according to the value(s) in the table
F A Center below.
E DC B
Standard:
FSR-
FSR- FSR+ FSR+ Tester connection Condition Specified condition
A22-1 (FSR+) -
Ignition switch ON Below 1 V
Body ground (*1)
A22 A22 A22-2 (FSR-) -
Ignition switch ON Below 1 V
Body ground (*1)
A22-3 (FSR+) -
Ignition switch ON Below 1 V
Body ground (*2)
w/o Side Airbag w/ Side Airbag A22-10 (FSR-) -
Ignition switch ON Below 1 V
H41715 H44130 H44536 Body ground (*2)
*1: w/ Side airbag
*2: w/o Side airbag
NG Go to step 12
OK
4 CHECK AIRBAG SENSOR ASSY CENTER COMMUNICATION CIRCUIT(OPEN)
(a) Disconnect the connectors from the airbag sensor assy
Occupant
center and the occupant classification ECU.
Airbag (b) Using a service wire, connect O3-8 (FSR+) and O3-4
Classification ECU Sensor
(FSR-) of connector "E".
Assy
F A Center NOTICE:
E DC B Do not forcibly insert a service wire into the terminals of the
FSR+ connector when connecting.
FSR-
FSR+ (c) Measure the resistance according to the value(s) in the
table below.
FSR- Standard:
O3
Tester connection Condition Specified condition
FSR+ FSR- A22-1 (FSR+) -
Always Below 1
A22-2 (FSR-) (*1)
A22 (*2) A22 (*1) A22-3 (FSR+) -
Always Below 1
A22-10 (FSR-) (*2)
Service Wire *1: w/ Side airbag
*1: w/ Side Airbag
*2: w/o Side airbag
*2: w/o Side Airbag
H44130 H44536
H41715 H43694 H44681
NG Go to step 13
OK
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1263
05-1081
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM
5 CHECK AIRBAG SENSOR ASSY CENTER COMMUNICATION CIRCUIT(SHORT)
(a) Disconnect the service wire from connector "E".
Occupant (b) Measure the resistance according to the value(s) in the
Airbag
Classification ECU
Sensor table below.
Assy Standard:
F A Center
Tester connection Condition Specified condition
E DC B
A22-1 (FSR+) -
FSR- Always 1 M or Higher
FSR+ A22-2 (FSR-) (*1)
FSR- FSR+
A22-3 (FSR+) -
Always 1 M or Higher
A22-10 (FSR-) (*2)
A22 A22 *1: w/ Side airbag
*2: w/o Side airbag
w/o Side Airbag w/ Side Airbag
H41715 H44130 H44536 NG Go to step 14
OK
6 CHECK AIRBAG SENSOR ASSY CENTER COMMUNICATION CIRCUIT(TO
GROUND)
(a) Turn the ignition switch to the LOCK position.
Occupant
Airbag (b) Disconnect the negative (-) terminal cable from the bat-
Classification ECU
Sensor tery, and wait for at least 90 seconds.
Assy (c) Measure the resistance according to the value(s) in the
F A Center table below.
E DC B
Standard:
FSR-
FSR- FSR+ FSR+ Tester connection Condition Specified condition
A22-1 (FSR+) -
Always 1 M or Higher
Body ground (*1)
A22 A22 A22-2 (FSR-) -
Always 1 M or Higher
Body ground (*1)
A22-3 (FSR+) -
Always 1 M or Higher
Body ground (*2)
w/o Side Airbag w/ Side Airbag A22-10 (FSR-) -
Always 1 M or Higher
H41715 H44130 H44536 Body ground (*2)
*1: w/ Side airbag
*2: w/o Side airbag
NG Go to step 15
OK
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1264
05-1082
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM
7 RECHECK DTC
(a) Connect the connectors to the occupant classification ECU and the airbag sensor assy center.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch to the ON position.
(d) Clear the DTCs stored in memory (see page 05-777 ).
HINT:
First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assy center.
(e) Turn the ignition switch to the LOCK position.
(f) Turn the ignition switch to the ON position.
(g) Using the hand-held tester, check the DTCs (see page 05-777 ).
OK:
DTC B1790 is not output.
HINT:
Codes other than code B1790 may be output at this time, but they are not related to this check.
NG Go to step 8
OK
USE SIMULATION METHOD TO CHECK (SEE PAGE 05-770 )
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 60-67 ).
HINT:
Perform the inspection using parts from a normal vehicle if possible.
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 "Zero point calibration" (see page 05-767 ).
OK:
The "COMPLETED" is displayed.
NEXT
10 PERFORM SENSITIVITY CHECK
(a) Using the hand-held tester, perform "Sensitivity check" (see page 05-767 ).
Standard value: 27 to 33 kg (59.52 to 72.75 lb)
NEXT
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1265
05-1083
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM
11 RECHECK DTC
(a) Turn the ignition switch to the ON position.
(b) Clear the DTCs stored in memory (see page 05-777 ).
HINT:
First clear DTCs stored in the occupant classification ECU and then in the airbag sensor assy center.
(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 (see page 05-777 ).
OK:
DTC B1790 is not output.
HINT:
Codes other than code B1790 may be output at this time, but they are not related to this check.
NG REPLACE AIR BAG SENSOR ASSY CENTER
(SEE PAGE 60-56 )
OK
END
12 CHECK FRONT SEAT WIRE RH(TO B+)
(a) Turn the ignition switch to the LOCK position.
Occupant Floor Wire No.2
Front Seat (b) Disconnect the negative (-) terminal cable from the bat-
Classification Wire RH Airbag tery, and wait for at least 90 seconds.
ECU Sensor
(c) Disconnect the front seat wire RH connector from the floor
Assy
wire No.2.
F A Center
(d) Connect the negative (-) terminal cable to the battery,
E D C B
and wait for at least 2 seconds.
BM1 (*2) (e) Turn the ignition switch to the ON position.
BO1 (*1) FSR- FSR+ (f) Measure the voltage according to the value(s) in the table
below.
FSR- Standard:
FSR+
Tester connection Condition Specified condition
BO1-3 (FSR+) -
*1: w/ Power Seat Ignition switch ON Below 1 V
*2: w/o Power Seat
Body ground (*1)
H45994
BO1-5 (FSR-) -
Ignition switch ON Below 1 V
Body ground (*1)
BM1-3 (FSR+) -
Ignition switch ON Below 1 V
Body ground (*2)
BM1-2 (FSR-) -
Ignition switch ON Below 1 V
Body ground (*2)
*1: w/ Power seat
*2: w/o Power seat
NG REPAIR OR REPLACE FRONT SEAT WIRE RH
OK
REPAIR OR REPLACE FLOOR WIRE NO.2
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1266
05-1084
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM
13 CHECK FRONT SEAT WIRE RH(OPEN)
(a) Disconnect the front seat wire RH connector from the floor
Occupant Floor Wire No.2
Front Seat wire No.2.
Classification Wire RH Airbag HINT:
ECU Sensor
The service wire has already been inserted into connector "E".
Assy
(b) Measure the resistance according to the value(s) in the
F A Center
table below.
E D C B
BO1 (*1) Standard:
Tester connection Condition Specified condition
BO1-3 (FSR+) -
FSR+ Always Below 1
BO1-5 (FSR-) (*1)
FSR+ O3 FSR-
BM1-3 (FSR+) -
Always Below 1
BM1-2 (FSR-) (*2)
FSR- *1: w/ Power seat
BM1 (*2) *2: w/o Power seat
FSR- FSR+
Service Wire
*1: w/ Power Seat
*2: w/o Power Seat H45993 NG REPAIR OR REPLACE FRONT SEAT WIRE RH
OK
REPAIR OR REPLACE FLOOR WIRE NO.2
14 CHECK FRONT SEAT WIRE RH(SHORT)
(a) Disconnect the front seat wire RH connector from the floor
Occupant Floor Wire No.2
Front Seat wire No.2.
Classification Wire RH Airbag (b) Measure the resistance according to the value(s) in the
ECU Sensor
table below.
Assy
Standard:
F A Center
Tester connection Condition Specified condition
E D C B
BO1-3 (FSR+) -
Always 1 M or Higher
BO1-5 (FSR-) (*1)
BM1 (*2)
BM1-3 (FSR+) -
BO1 (*1) FSR- FSR+ Always 1 M or Higher
BM1-2 (FSR-) (*2)
FSR-
FSR+
*1: w/ Power Seat
*2: w/o Power Seat H45994 NG REPAIR OR REPLACE FRONT SEAT WIRE RH
OK
REPAIR OR REPLACE FLOOR WIRE NO.2
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1267
05-1085
DIAGNOSTICS - SUPPLEMENTAL RESTRAINT SYSTEM
15 CHECK FRONT SEAT WIRE RH(TO GROUND)
(a) Disconnect the front seat wire RH connector from the floor
Occupant Floor Wire No.2
Front Seat wire No.2.
Classification Wire RH Airbag (b) Measure the resistance according to the value(s) in the
ECU Sensor
table below.
Assy
Standard:
F A Center
Tester connection Condition Specified condition
E D C B
BO1-3 (FSR+) -
Always 1 M or Higher
Body ground (*1)
BM1 (*2)
BO1-5 (FSR-) -
BO1 (*1) FSR- FSR+ Always 1 M or Higher
Body ground (*1)
BM1-3 (FSR+) -
Always 1 M or Higher
FSR- Body ground (*2)
FSR+
BM1-2 (FSR-) -
Always 1 M or Higher
Body ground (*2)
*1: w/ Power Seat
*2: w/o Power Seat H45994 *1: w/ Power seat
*2: w/o Power seat
NG REPAIR OR REPLACE FRONT SEAT WIRE RH
OK
REPAIR OR REPLACE FLOOR WIRE NO.2
2005 SIENNA REPAIR MANUAL (RM1163U)
Author : Date : 1268
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