2001 TOYOTA PRIUS relay

I18389
A/C Amplifier
IG A71
GND A77
F18
FL Block No. 2
BatteryInstrument Panel J/B
I15
Ignition
SW J20
J/C
C
R C
R 2D3
2H1
2D6
2K8
2B3
8
2D HTR
IG1 Relay
AM1B±Y
J/C 35
21
4
IG1
AM1
2
W
J25A
J24A
A
J11
J/C
ID MAINFL Block No. 1
F111
F131
4DC/DC
B±GW±B
W±B
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±921
2001 PRIUS (RM778U)
IG Power Source Circuit
CIRCUIT DESCRIPTION
This is the power source for the A/C amplifier (contains the ECU) and servomotors, etc.
WIRING DIAGRAM
DI7SI±01

I18388
A/C Amplifier
11
A7MPX+ GR
4
MPX+
BJ6
J/C
HTR Relay
J/C
Battery4
A7
MP2+ C11
Combination Meter
MPX±
11 GR±B
MPX1 MPX2
10
B8
14 13
11
B8 MPX+
MPX±
MPD2
MPD1
Instrument Panel J/B
HRLY6
2FL±O
BR R 4
1F
5 3
2
HTR
13
1J
8
1K
3
1B
3
1K
To Blower Motor
W13
IE1
R
A
J23
CJ22
R
FL Block
No. 1 DC/DC
B±G
F11 1
F13 1
1
MAINW±B
A F18
FL Block
No. 2
AWInstrument Panel J/B
1
2H
8
2K
IG1
Relay
3
25
1AM1
W±GI15
Ignition
SW
HTRAM1
3
2B
6
2D
3
2D
IG12
4
B±Y
J11
J/C
ID
IE W±BA
AJ1
J/C
3 2
E10 E10ECM
GR
GR±LC1
Gateway ECU
GR±B
J7 J/C
Engine Room J/B Body ECU DI±926
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
Heater Main Relay Circuit
CIRCUIT DESCRIPTION
The heater main relay is switched on by signals from the A/C amplifier. It supplies power to the blower motor.
WIRING DIAGRAM
DI7SK±01

BE1850 BE1844I00312125
3
125
3
4
4
I18394
Engine Room J/B
HTR
Fuse
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±927
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check heater main relay.
PREPARATION:
Remove heater main relay from engine room J/B.
CHECK:
Check continuity between each pair of terminals of heater main
relay shown below.
OK:
Tester connectionSpecified condition
1 ± 4No continuity
2 ± 4Continuity
3 ± 562.5 ± 90.9 W
PREPARATION:
Apply battery positive voltage between terminals 3 and 5.
CHECK:
Check continuity between each pair of terminal shown below.
OK:
Tester connectionSpecified condition
1 ± 2Continuity
2 ± 4No continuity
NG Replace hater main relay.
OK
2 Check HTR fuse
PREPARATION:
Remove HTR fuse from engine room J/B.
CHECK:
Check continuity of HTR fuse.
OK:
Continuity exists.
NG Check for short in all the harness and compo-
nents connected to the HTR fuse (See page
IN±41).
OK

DI±928
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
3 Check harness and connector between heater main relay and body ground, heat-
er main relay and body ECU (See page IN±41).
NG Check and replace harness and connector.
OK
Check multiplex communication system (See page DI±750).

Duty Ratio =A + BA
x 100 (%)
ON
OFFA
B
1 cycle
Blower Level
0
Si duty (%)
LO M1M2HI
3043
67100
I18383
B7
Blower Motor Liner ControllerA/C Amplifier
B6 Blower Motor J2A21
C
A73
BLW
From
HTR RelayV IE1
V C J6
J/C
V
J2ASI
GND
+B J/C
J3A
VMW±B
A
J1
J/C
IE
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±929
2001 PRIUS (RM778U)
Blower Motor Circuit
CIRCUIT DESCRIPTION
The blower motor is operated by signals from the A/C amplifier.
Blower motor speed signals are transmitted by changes in the
Duty Ratio.
Duty Ratio
The duty ratio is the ratio of the period of continuity in one cycle.
For example, if A is the period of continuity in one cycle, and B
is the period of non±continuity, then.
WIRING DIAGRAM
DI7SL±01

I18387
LG±R
IE18
1
F18
FL Block No. 2
BatteryInstrument Panel J/B
I15
Ignition
SW J6
J/C
AA E1022
1F3
1A5
2D6
2K8
3
2B Engine Room J/B
IG1 Relay ACT
B±Y 35
21
4
IG1
AM1
2 W
A
J11
J/C
ID MAINFL Block No. 1
F111
F131
1DC/DC
B±GW±BA/C Amplifier
A2
A/C Magnetic
Clutch W±G AM12H1 2D3 HTRCLR MG Relay
1F4 12
5
3A85
ACT
A8 10
MGC LG±R
B±L
IE113
R
R
R
J/C
J21A
J20C
R ECM DI±932
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
Compressor Circuit
CIRCUIT DESCRIPTION
A/C amplifier switches the A/C magnetic clutch relay ON, thus turning the A/C compressor magnetic clutch
ON.
WIRING DIAGRAM
DI7SM±01

I18169
MGC
(+)
(±) ON
Z18060
15 2
3
12 3 5
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±933
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminal MGC of A/C amplifier and body ground.
CHECK:
(a) Start engine.
(b) Push AUTO SW.
(c) Measure voltage between terminal MGC of A/C amplifier
connector and body ground when A/C switch is On and
OFF.
OK:
A/C switchVoltage
ONBelow 0.7 V
OFF10 ± 14 V
OK Go to step 5.
NG
2 Check magnetic clutch relay.
PREPARATION:
Remove magnetic clutch relay from engine room J/B.
CHECK:
Check continuity between each pair of terminals shown below
of magnetic clutch relay.
OK:
Tester connectionSpecified condition
1 ± 262.5 ± 90.9 W
3 ± 5No continuity
PREPARATION:
Apply battery positive (+) voltage between terminals 1 and 2.
CHECK:
Check continuity between terminals 3 and 5.
OK:
Continuity exists.
NG Replace magnetic clutch relay.
OK

I18006
1
I18156
ACT
DI±934
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
3 Check A/C magnetic clutch.
PREPARATION:
Disconnect magnetic clutch connector.
CHECK:
Connect positive (+) lead connected to battery to magnetic
clutch connector terminal 3 and negative (±) lead to body
ground.
OK:
Magnetic clutch is energized.
NG Repair A/C magnetic clutch.
OK
4 Check harness and connector between magnetic clutch relay and A/C amplifier,
A/C compressor and body ground (See page IN±41).
NG Repair or replace harness or connector.
OK
Proceed to next circuit inspection shown on
problem symptons table (See page DI±874).
5 Check voltage between terminal ACT of A/C amplifier connector side and body
ground.
PREPARATION:
(a) Disconnect A/C amplifier connector.
(b) Turn ignition switch ON.
CHECK:
Check voltage between terminal ACT of A/C amplifier harness
side connector.
OK:
Voltage : 10 ± 14 V
NG Check and replace engine ECU.
OK