2001 TOYOTA PRIUS light

H15524
B±W
W5
2BB±O
GR
W±B ACC Relay 10A SRS ACC
5A AM1
FL Block No. 2 FL Block No. 1 15A AM2
Battery 100A
DC/DCB±G W±RA
J11
J/C W±G
W±R P±L1
2H
8
2C2
2E
4
2E
8
2K
2B 536
A18ACC
120A
1 1
F13 1
F12
1
F11 1B9 2
1J B1
2G2
2C ACC
2
67AM1
AM2 IG2MAIN
35
A18IG2 Airbag Sensor
Assembly Instrument Panel J/B
Ignition Switch
ID 12
3
Instrument Panel J/B Engine Room J/B DI±634
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
2001 PRIUS (RM778U)
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
WIRING DIAGRAM
DI6PY±07

AB0119H01298H01299
Airbag Sensor Assembly
ON
IG1
ACC
(+) (±)
H01249
ON
DI±636
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
2001 PRIUS (RM778U)
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
IG1 and IG2 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.

H15525
Combination Meter
Instrument Panel J/B
10A ACC
ACC Relay
5A AM1
W±G L15
C10
16
C10
5
C11
GR±RGR±R
W±BB±Y 9
2A
2
2D
8
2A
1
2H
8
2C
3
2B53
128
2K4
2B 1
2E3
A18LA
1
F11C
J27
Fl Block No. 1
23P±LW 1
F13
1 B±GL
GR±R
BBC
J28AB
A
J11
J/C
Battery F18
FL
Block
No. 2DLC3
DC/DC100A
J/C
I15 Ignition S/W
120A
MAINAirbag Sensor
Assembly
B±Y6
ID J26
J/C
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±637
2001 PRIUS (RM778U)
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 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 CG of the DLC3 are connected, the DTC is displayed by blinking the SRS warning
light.
WIRING DIAGRAM
DI7QT±01

AB0117H01293H01295
Airbag Sensor Assembly
LOCK
DI±638
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
Always lights up, when ignition switch is in LOCK position
1 Prepare for inspection (See step 1 on page DI±629).
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 A/B
circuit of DLC3.
YES
Replace airbag sensor assembly.

N14677
Fuse
AB0119H01300
H01301
Airbag Sensor Assembly
ON
LA
(+)
(±)
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±639
2001 PRIUS (RM778U)
Does not light up, when ignition switch is turned to ON
1 Check AM2 Fuse.
PREPARATION:
Remove the AM2 fuse.
CHECK:
Check continuity of the AM2 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 4.
OK
2 Prepare for inspection (See step 1 on page DI±629).
3 Check SRS warning light circuit.
PREPARATION:
(a) Disconnect the airbag sensor assembly connector.
(b) Connect negative (±) terminal cable to the battery.
(c) Turn the ignition switch to 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 combination meter or repair SRS warn-
ing light circuit.
OK
Replace airbag sensor assembly.

DI±640
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
2001 PRIUS (RM778U)
4 Is new AM2 fuse burnt out again?
NO Using simulation method, reproduce malfunc-
tion symptoms (See page IN±30).
YES
Check harness between AM2 fuse and SRS
warning light.

H15526
J11
J/C AW±B 2KW±BJ24
J/C
W±BDLC3
P±BJ26
J/C
P±B
Tc
8 2D 8AA
413 CGTc
E
E19
A18
Instrument Panel J/BAirbag Sensor
Assembly
ID
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
DI±641
2001 PRIUS (RM778U)
Tc Terminal Circuit
CIRCUIT DESCRIPTION
By connecting terminals Tc and CG of the DLC3 the airbag sensor assembly is set in the DTC output mode.
The DTCs are displayed by blinking the SRS warning light.
WIRING DIAGRAM
DI6Q0±06

AB0117AB0119H15218H15700
LOCK
ON
AB0119H10688H10654
ON
CG
Tc
(+) (±)
DI±642
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
If the DTC is not displayed, do the following troubleshooting.
1 Does SRS warning light light up for approx. 6 seconds?
PREPARATION:
Check operation of the SRS warning light after ignition switch
is turned from LOCK position to ON position.
NO Check SRS warning light system (See page
DI±632).
YES
2 Check voltage between terminals Tc and CG of DLC3.
PREPARATION:
Turn the ignition switch to ON.
CHECK:
Measure the voltage between terminals Tc and CG of DLC3.
OK:
Voltage: 10 ± 14 V
OK Go to step 4.
NG