2001 TOYOTA PRIUS Service Repair Manual

DI±942
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
PTC Heater Circuit (Quick Heater)
CIRCUIT DESCRIPTION
A/C amplifier switches the HTR3 relay ON by signal from the A/C amplifier. It supplies power to PTC heater
(Quick heater).
DI7SP±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
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±943
2001 PRIUS (RM778U)
WIRING DIAGRAM

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