Page 1473 of 2572

I30331GND (-)IG (+) A/C Amplifier Connector
Wire Harness View:
A10
I38763
GND
A/C Amplifier Connector Wire Harness View:
A10
- DIAGNOSTICSAIR CONDITIONING SYSTEM
05-1 171
1361 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
INSPECTION PROCEDURE
1 CHECK FUSE(HEATER, AM1 FUSES)
(a) Remove the HEATER and AM1 fuses from the instrument panel J/B.
(b) Check that the continuity exists in HEATER and AM1 fuses.
NG REPLACE FUSE
OK
2 INSPECT AIRCONDITIONER AMPLIFIER ASSY(IG, GND)
(a) Remove the A/C amplifier assy with connectors still con-
nected.
(b) Measure the voltage according to the value(s) in the table
below.
Standard:
Tester connectionConditionSpecified condition
A10-2 (IG) -
A10-1 1 (GND)Ignition switch ON10 to 14 V
OK PROCEED TO NEXT CIRCUIT INSPECTION
SHOWN IN PROBLEM SYMPTOMS TABLE (SEE
PAGE 05-1 129)
NG
3 CHECK HARNESS AND CONNECTOR(A/C AMPLIFIER ASSY - BODY GROUND)
(a) Measure the resistance according to the value(s) in the
table below.
Standard:
Tester connectionConditionSpecified condition
A10-1 1 (GND) -
Body groundAlwaysBelow 1 W
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
Page 1474 of 2572
I38763
IG
A/C Amplifier Connector Wire Harness View:
A10
05-1 172
- DIAGNOSTICSAIR CONDITIONING SYSTEM
1362 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
4 CHECK HARNESS AND CONNECTOR(A/C AMPLIFIER ASSY - BATTERY)
(a) Measure the resistance according to the value(s) in the
table below.
Standard:
Tester connectionConditionSpecified condition
A10-2 (IG) -
Body groundIgnition switch
OFF " ONBelow 1.0 V " 10 to 14 V
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
REPLACE AIRCONDITIONER AMPLIFIER ASSY
Page 1475 of 2572
I30515
+B A1012
1K
IC3Instrument Panel J/B
W 2
1ECU-B Engine Room J/B
FL MAIN
BatteryA/C Amplifier Assy
10
1G BR W-L5 4
2A D.C.C
2I W
1 3
WF7
Fusible
Link
Block
- DIAGNOSTICSAIR CONDITIONING SYSTEM
05-1 173
1363 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
BACK-UP POWER SOURCE CIRCUIT
CIRCUIT DESCRIPTION
This is the back-up power source for the A/C amplifier assy. Power is supplied even when the ignition switch
is off and is used for diagnostic trouble code memory, etc.
WIRING DIAGRAM
05IU3-01
Page 1476 of 2572

I30331+B (+)
A/C Amplifier Connector
Wire Harness View:
A10
I38763
A10
GND+B
A/C Amplifier Connector Wire Harness View:
05-1 174
- DIAGNOSTICSAIR CONDITIONING SYSTEM
1364 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
INSPECTION PROCEDURE
1 CHECK FUSE(ECU-B FUSE)
(a) Remove the ECU-B fuse from the engine room J/B.
(b) Check that the continuity exits of ECU-B fuse.
NG REPLACE FUSE
OK
2 INSPECT AIRCONDITIONER AMPLIFIER ASSY(+B)
(a) Remove the A/C amplifier assy with connectors still con-
nected.
(b) Measure the voltage according to the value(s) in the table
below.
Standard:
Tester connectionConditionSpecified condition
A10-12 (+B) -
Body groundAlways10 to 14 V
OK PROCEED TO NEXT CIRCUIT INSPECTION
SHOWN IN PROBLEM SYMPTOMS TABLE (SEE
PAGE 05-1 129)
NG
3 CHECK HARNESS AND CONNECTOR(A/C AMPLIFIER ASSY - BATTERY)
(a) Remove the A/C amplifier assy and disconnect the con-
nector.
(b) Measure the voltage according to the value(s) in the table
below.
Standard:
Tester connectionConditionSpecified condition
A10-12 (+B) -
A10-1 1 (GND)Always10 to 14 V
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
REPLACE AIRCONDITIONER AMPLIFIER ASSY
Page 1477 of 2572
I40780
A/C Amplifier Assy
A10 HR O
1H9
Heater
Relay
35
G7
2 J5
J/C
HEATER 10A
AM17
IG1
1
28
6 I15
Ignition SW
A
W
FL MAIN
BatteryInstrument Panel J/B
IL2 BR Y
Y
A 1G
1A 1C 1C
1 4 2
W
1
7
F7
Fusible Link BlockALTHEATER 50A 2B
B-YW
1 IK442
4H4L7 7
W-B
W-B
IC Passenger Side J/BFrom Blower
Motor AM1B
- DIAGNOSTICSAIR CONDITIONING SYSTEM
05-1 187
1377 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
HEATER RELAY CIRCUIT
CIRCUIT DESCRIPTION
The heater relay is switched on by signals from the A/C amplifier assy. It supplies power to the blower motor.
WIRING DIAGRAM
05IU7-03
Page 1478 of 2572

Z19533
5
4 3
12125
4 3
I30331HR
A/C Amplifier Connector
Wire Harness View:
A10
05-1 188
- DIAGNOSTICSAIR CONDITIONING SYSTEM
1378 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
INSPECTION PROCEDURE
1 CHECK FUSE(15 A HEATER, 50 A HEATER, AM1 FUSES)
(a) Remove the 15 A HEATER and AM1 fuses from the instrument panel J/B.
(b) Remove the 50 A HEATER fuse from fusible link block.
(c) Check that the continuity exists in 15 A HEATER and 50 A HEATER, AM1 fuses.
NG REPLACE FUSE
OK
2 INSPECT HEATER BLOWER MOTOR RELAY ASSY
(a) Check that the continuity exists between each pair of ter-
minals of heater blower motor relay assy, as shown in the
chart.
Tester connectionConditionSpecified condition
2 - 1Always10 kW or higher
2 - 4AlwaysBelow 1.0 W
(b) Check continuity between each pair of terminals, as
shown the chart.
Tester connectionConditionSpecified condition
2 - 1When battery voltage ap-
plied to terminals 3 and 5Below 1.0 W
2 - 4When battery voltage ap-
plied to terminals 3 and 510 kW or higher
NG REPLACE HEATER BLOWER MOTOR RELAY
ASSY
OK
3 INSPECT AIRCONDITIONER AMPLIFIER ASSY(HR)
(a) Remove the A/C amplifier assy with connectors still con-
nected.
(b) Measure the voltage according to the value(s) in the table
below.
Standard:
Tester connectionConditionSpecified condition
A10-7 (HR) -
Body groundIgnition switch OFF0 V
A10-7 (HR) -
Body groundIgnition switch ON
Blower switch ONBelow 1.0 V
A10-7 (HR) -
Body groundIgnition switch ON
Blower switch OFF10 to 14 V
OK PROCEED TO NEXT CIRCUIT INSPECTION
SHOWN IN PROBLEM SYMPTOMS TABLE
NG
Page 1479 of 2572
I38763
A10
A/C Amplifier Connector Wire Harness View:
HR
- DIAGNOSTICSAIR CONDITIONING SYSTEM
05-1 189
1379 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
4 CHECK HARNESS AND CONNECTOR
(a) Measure the voltage according to the value(s) in the table
below.
Standard:
Tester connectionConditionSpecified condition
A10-7 (HR) -
Body groundIgnition switch
OFF " ONBelow 1 V " 10 to 14 V
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
REPAIR OR REPLACE AIRCONDITIONER AMPLIFIER ASSY
Page 1480 of 2572
I30520
ECM
ACMG 2
E6 O
IK3 Magnetic Clutch Relay
9 18 From Fan No. 3
Relay
Y-G
Y-G
EB2
B-Y
3 2
3 8
A2
A/C Magnetic
Clutch and
Lock Sensor 3 2 1
52C
2E 2A B-R
IK27Engine Room J/B
Y From
Battery 05-1 190
- DIAGNOSTICSAIR CONDITIONING SYSTEM
1380 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
COMPRESSOR CIRCUIT
CIRCUIT DESCRIPTION
The ECM and A/C amplifier communicate via BEAN.
The A/C amplifier assy outputs the magnetic clutch ON signal to the ECM.
Receiving this signal, the ECM sends a signal through terminal ACMG and switches the magnetic clutch
relay ON, thus turning on the magnetic clutch.
WIRING DIAGRAM
05IU8-01