TOYOTA AVALON 2001 Service Repair Manual

- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI-475
631 Author
: Date
:
2001 AVALON (RM808U)
DTC Normal Source Voltage Drop
CIRCUIT DESCRIPTION
The SRS is equipped with a voltage-increase circuit (DC-DC converter) in the airbag sensor assembly in
case the source voltage drops.
When the battery voltage drops, the voltage-increase circuit (DC-DC converter) functions to increase the
voltage of the SRS to normal voltage.
The diagnosis system malfunction display for this circuit is different from other circuits that is when the SRS
warning light remains lit up and the DTC is a normal code, source voltage drop is indicated.
Malfunction in this circuit is not recorded in the airbag sensor assembly, and the source voltage returns to
normal, the SRS warning light automatically goes off.
DTC No.Diagnosis
(Normal)Source voltage drop
DI1NV-16

H12003
Airbag Sensor
Assembly
I15
Ignition Switch
Engine Room R/B No. 5IG2 C6ACC 1F
5 6
B-O
B-LC6 W-G
ALTGR
1F
1C 1CDriver Side J/B
10 10
1 7
B-O3
6 2
7 W-L 7
BatteyFL MAINF6 IF1 W-L
IF1W-R 4
W-R
5
5 AM1
21
Engine Room J/BFL Block
72
112G
2G 2C
2HAM2
B
F7
F81
1
B1 SRS-ACC
BAM1ACC
AM2 IG2 DI-476
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
632 Author
: Date
:
2001 AVALON (RM808U)
WIRING DIAGRAM

H01026H06508H06509
LOCK
Airbag Sensor
Assembly
P Squib
D Squib
P/T Squib (LH)
Side Squib
(LH)
P/T Squib (RH)
Side Squib
(RH)
Spiral
Cable
Side Airbag
Sensor (LH)
Side Airbag
Sensor (RH) Front Airbag
Sensor (LH)
Front Airbag
Sensor (RH)
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI-477
633 Author
: Date
:
2001 AVALON (RM808U)
INSPECTION PROCEDURE
1 Prepare for inspection.
PREPARATION:
(a) Disconnect negative (-) terminal cable from the battery,
and wait at least for 90 seconds.
(b) Remove the steering wheel pad (See page SR-12).
(c) Disconnect the connector of the front passenger airbag
assembly (See page RS-28).
(d) Disconnect the connector of the side airbag assembly RH
and LH (See page RS-42 and RS-56).
(e) Disconnect the connector of the seat belt pretensioner
RH and LH (See page BO-128).
(f) Disconnect the connectors of the airbag sensor assembly
(See page RS-63 and RS-68).
(g) Disconnect the connector of the front airbag sensor RH
and LH (See page RS-73).
(h) Disconnect the connector of the side airbag sensor as-
sembly RH and LH (See page RS-78).
CAUTION:
Store the steering wheel pad, front passenger airbag as-
sembly and side airbag assemlby with the front surface
facing upward.

AB0119H01298H01299
Airbag Sensor Assembly
ON
ACC
IG2
(+) (-)
H01249
ON
DI-478
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
634 Author
: Date
:
2001 AVALON (RM808U)
2 Check source voltage.
PREPARATION:
Connect negative (-) terminal cable to the battery.
CHECK:
(a) Turn ignition switch ON.
(b) Measure the voltage between body ground and each of
IG2 and ACC on the sensor and operate electric system
(defogger, wiper, headlight, heater blower, etc.).
OK:
Voltage: 10 - 14 V
NG Check harness between battery and airbag sen-
sor assembly, and check battery and charging
system.
OK
3 Does SRS warning light turn off?
PREPARATION:
(a) Turn the ignition switch to LOCK.
(b) Connect the steering wheel pad connector.
(c) Connect the front passenger airbag assembly connector.
(d) Connect the side airbag assembly connectors.
(e) Connect the seat belt pretensioner connectors.
(f) Connect the airbag sensor assembly connectors.
(g) Connect the front airbag sensor connectors.
(h) Connect the side airbag sensor assembly connectors.
(i) Turn the ignition switch to ON.
CHECK:
Operate electric system (defogger, wiper, headlight, heater
blower, etc.) and check that SRS warning light goes off.
NO Check for DTCs. If a DTC is output, perform trou-
bleshooting for the DTC. If a normal code is out-
put, replace airbag sensor assembly.
YES
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.

H12004
Battery10Airbag Sensor Assembly
LA
C63
B-Y 5 12
1F 1A1I
II2
B-Y 5 B-Y
5 AB DLC1
B-Y
56 M7
SRS Warning Light
LG-B
IJ1 4
LG-B
2G 2B
SRS WRN
Engine Room J/BB
FL Block F7
F6 1
1
B FL MAINDriver Side J/B
12
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI-479
635 Author
: Date
:
2001 AVALON (RM808U)
SRS Warning Light Circuit Malfunction
CIRCUIT DESCRIPTION
The SRS warning light is located on the combination meter.
When the SRS is normal, the SRS warning light lights up for approx. 6 seconds after the ignition switch is
turned from the LOCK position to ACC or ON position, and then turns off automatically.
If there is a malfunction in the SRS, the SRS warning light lights up to inform the driver of the abnormality.
When terminals Tc and E1 of the DLC1 are connected, the DTC is displayed by blinking the SRS warning
light.
WIRING DIAGRAM
DI5RJ-04

AB0117H01293H01295
Airbag Sensor Assembly
LOCK
DI-480
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
636 Author
: Date
:
2001 AVALON (RM808U)
INSPECTION PROCEDURE
Always lights up, when ignition switch is in LOCK position
1 Prepare for inspection (See step 1 on page DI-475).
2 Does SRS warning light turn off?
PREPARATION:
(a) Turn the ignition switch to LOCK.
(b) Disconnect negative (-) terminal cable from the battery,
and wait at least for 90 seconds.
(c) Disconnect the airbag sensor assembly connector.
(d) Connect negative (-) terminal cable to the battery.
CHECK:
Check operation of SRS warning light.
NO Check SRS warning light circuit or terminal AB
circuit of DLC1.
YES
Replace airbag sensor assembly.

N14677
Fuse
AB0119H01300
H01301
Airbag Sensor Assembly
ON
LA
(+)
(-)
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI-481
637 Author
: Date
:
2001 AVALON (RM808U)
Does not light up, when ignition switch is turned to ACC or ON
1 Check ECU-B Fuse.
PREPARATION:
Remove the ECU-B fuse.
CHECK:
Check continuity of the ECU-B fuse.
OK:
Continuity
HINT:

Fuse may be burnt out even if it appears to be OK during
visual inspection.

If fuse is OK, install it.
NG Go to step 5.
OK
2 Prepare for inspection (See step 1 on page DI-475).
3 Check SRS warning light circuit.
PREPARATION:
(a) Connect negative (-) terminal cable to the battery.
(b) Turn the ignition switch to ACC or ON.
CHECK:
Measure the voltage between body ground and LA terminal of
the harness side connector of the airbag sensor assembly.
OK:
Voltage: 10 - 14 V
NG Check SRS warning light bulb or repair SRS
warning light circuit.
OK

H08325AB0119H11969H13045
P/T Squib (LH)
Side Airbag
Sensor (LH)
Side Squib (LH)P Squib
D Squib
Spiral
Cable
Front Airbag
Sensor (RH) Front Airbag
Sensor (LH)
P/T Squib (RH)
Side Squib (RH)Side Airbag
Sensor (RH)
ONAirbag
Sensor
Assembly
DI-482
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
638 Author
: Date
:
2001 AVALON (RM808U)
4 Does SRS warning light come on?
PREPARATION:
(a) Disconnect negative (-) terminal cable from the battery.
(b) Connect the airbag sensor assembly connector.
(c) Connect negative (-) terminal cable to the battery, and
wait at least for 2 seconds.
(d) Turn the ignition switch to ACC or ON.
CHECK:
Check operation of the SRS warning light.
NO Check terminal LA of airbag sensor assembly.
If normal, replace airbag sensor assembly.
YES
From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use simulation method to check.

- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI-483
639 Author
: Date
:
2001 AVALON (RM808U)
5 Is new ECU-B fuse burnt out again?
NO Using simulation method, reproduce malfunc-
tion symptoms (See page IN-20).
YES
Check harness between ECU- B fuse and
SRS warning light.

H12005
Airbag Sensor Assembly
Tc
C6
E1
W-B19
P-B 56
1F 1IDriver Side J/B
LG-R
11 3A
3G3B 413
4
J/B No. 3LG-R 4Tc DLC2
LG-R
J/B No. 4
66
4A
4HLG-R
II2 22
LG-R
DLC1
EB
3Tc DI-484
- DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
640 Author
: Date
:
2001 AVALON (RM808U)
Tc Terminal Circuit
CIRCUIT DESCRIPTION
By connecting terminals Tc and E1 of the DLC1 the airbag sensor assembly is set in the DTC output mode.
The DTCs are displayed by blinking the SRS warning light.
WIRING DIAGRAM
DI1BQ-18