TOYOTA PRIUS 2001 Service Repair Manual

I18174
ON
HTR2(+) (±)
DI±944
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check converter circuit (See page DI±934).
2 Check voltage between terminal HTR2 of A/C amplifier and body ground.
PREPARATION:
Remove the center cluster module control with connectors still
connected.
CHECK:
(a) Start engine.
(b) Set temperature control switch on ºMAX. WARMº posi-
tion.
(c) Set blower switch on ºHIº position.
(d) Turn light control switch OFF.
(e) Turn defogger switch OFF.
(f) Check voltage between terminal HTR2 of A/C amplifier
and body ground at each conditions, as shown in the
chart.
OK:
ConditionVoltage

Air flow selector: FOOT

Water temp. : Below 65°C (149°F)Below 0.7 V

Air flow selector: FOOT/DEF

Water temp. : Below 60°C (140°F)Below 0.7 V

Air flow selector: DEF

Water temp. : 75°C (167°F)Below 0.7 V
OK Go to step 6.
NG

I18396
Engine Room R/B No. 3
HTR3 Fuse
Z18060
15 2
3
123 5
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±945
2001 PRIUS (RM778U)
3 Check HTR3 fuses.
PREPARATION:
Remove the HTR3 fuse from engine room R/B No. 3.
CHECK:
Check continuity of HTR1 and HTR2 fuses.
OK:
Continuity exists.
NG Check for short in all the harness and compo-
nents connected to the HTR1 and HTR2 fuses
(See attached wiring diagram).
OK
4 Check HTR3 relays.
PREPARATION:
Remove the HTR3 relays from engine room relay block No. 3.
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 HTR3 relay.
OK

I18393
DI±946
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
5 Check harness and connector between A/C amplifier and HTR1 and HTR2 fuses
(See page IN±41).
NG Check and replace harness and connector.
OK
Check and replace A/C amplifier.
6 Check PTC heater.
PREPARATION:
Remove the heater radiator (See page AC±51).
CHECK:
Check continuity between terminals of PTC heater connector,
as shown in the chart.
OK:
Tester connectionResult
1 ± 2Continuity
3 ± 4Continuity
NG Replace heater radiator.
OK
Check harness and connector between PTC heater and HTR1, HT2 relays, PTC heater and body
ground (See page IN±41).

± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±947
2001 PRIUS (RM778U)
PTC Heater Circuit (Heater Radiator)
CIRCUIT DESCRIPTION
A/C amplifier switches the HTR1 relay and HTR2 relay ON by signal from the A/C amplifier. It supplies power
to PTC heater (Heater radiator).
DI7SQ±01

I18386
A8 A8 13
6HTR2
HTR0 A/C Amplifier
P P
IE118
IE116 L±R
P±B
P±B
P±B
L±Y
G±R
1
23
41
2 P2
P2P2
P2P1
P1PTC Heater
W±B
W±B W±B
W±B
W±B
J11
J/CJ1
J/C AA
AA
IE ID IA1
IA1 Engine Room R/B No.3
3
3
3
3
3
3 3
3
3
3
3
3
3
3
3
3HTR3 Relay
HTR2 Relay
HTR1 Relay1
2
5
3
1
2
5
3
1
2
5
3
HTR1
HTR2
HTR3 R±L
G
R±L
G±W
R±L
B±R
W
Instrument Panel J/B
2G
2D
2H
2K 2B8
6
1
8 3GAUGE
IG1 Relay
5 3
21
AM1
B±Y
W±G
24
AM1 IG1 I15
Ignition SW
DC/DCF13
F13 F131
1 1FL Block No.1
F18 FL Block No.2
BatteryMAINW±B
W5
1 DI±948
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
WIRING DIAGRAM

I18152
ON
HTR0
(+)
(±)
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±949
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check converter circuit (See page DI±934).
2 Check voltage between terminal HTR0, of A/C amplifier and body ground.
PREPARATION:
Remove the center cluster module control with connectors still
connected.
CHECK:
(a) Start engine.
(b) Set temperature control switch on ºMAX WARMº position.
(c) Set blower switch on ºHIº position.
(d) Turn light control switch to OFF.
(e) Turn defogger switch OFF.
(f) Check voltage between terminal HTR0 of A/C amplifier
and body ground at each conditions, as shown in the
chart.
OK:
ConditionVoltage

Air flow selector: FOOT

Water temp. : Below 60°C (140°F)Below 0.7 V

Air flow selector: FOOT/DEF

Water temp. : Below 50°C (122°F)Below 0.7 V
OK Go to step 6.
NG

I18396
Engine Room R/B No. 3
HTR1 Fuse HTR2 Fuse
Z18060
15 2
3
123 5
DI±950
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
3 Check HTR1 and HTR2 fuses.
PREPARATION:
Remove the HTR1 and HTR2 fuses from engine room R/B NO.
3.
CHECK:
Check continuity of HTR1 and HTR2 fuses.
OK:
Continuity exists.
NG Check for short in all the harness and compo-
nents connected to the HTR1 and HTR2 fuses
(See attached wiring diagram).
OK
4 Check HTR1 and HTR2 relays.
PREPARATION:
Remove the HTR1 and HTR2 relays from engine room relay
block NO. 3.
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 HTR1 and (or) HTR2 relay.
OK

I18395
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±951
2001 PRIUS (RM778U)
5 Check harness and connector between A/C amplifier and HTR3 fuse (See page
IN±41).
NG Check and replace harness and connector.
OK
Check and replace A/C amplifier.
6 Check PTC heater (Heater Radiator).
PREPARATION:
Remove the heater radiator (See page AC±27).
CHECK:
Check continuity between terminals of PTC heater connector.
OK:
Continuity exists.
NG Replace heater radiator.
OK
Check harness and connector between PTC heater and HTR3 relay, PTC heater and body ground
(See page IN±41).

DI±952
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
Radiator Fan and Condenser Fan Circuit
CIRCUIT DESCRIPTION
The electric fan speed is controlled as described below, in accordance with the following signals:

ON/OFF signal of A/C switch

ON/OFF signal detected by the pressure switch (that cut out at medium pressure)

ON/OFF signal detected by water temperature switch
DI7SR±01

I18401
A/C Amplifier
CF Engine Room J/B
Fan No.2 Relay
A9
A91
2RF IE16
R±W R±W
1J
1A
1J
1K
1J
1K
1B
1J
1K 1K 10
11
5
3
12
5
2
3
4
7 Fan No.1 Relay
Fan No.1 Relay1
2
5 3
4
1
2
5
3
3 5
12
CDS FAN
RDIV±YJ27
J28J27 EE
E J/C L±W To Engine ECU
W±B
V±Y
From
DC/DC Fuse
From ECU±
IG Fuse 1
1 2 R1 Radiator Fan Motor
W4 Water Temp. Switch12
W±B
W±BA3 A/C Pressure Switch2 3
J1
J/CJ7
J/C
AA A
AW±BW±B
IEV±Y
A1
A/C Condenser
Fan Motor
G±W
W±G
W
L±W2
W±B W±B
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±953
2001 PRIUS (RM778U)
WIRING DIAGRAM