Page 857 of 2572

I30155
Ambient Temperature Sensor:
A1
I38777
Temperature (C) 3.5
3.0
2.5
2.0
1.5
1.0
5.0
0.0
40 0
20 60 Resistance
(kW)4.0
C
F 104 68 140MIX
MAX
- DIAGNOSTICSTIRE PRESSURE WARNING SYSTEM
05-759
949 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
4 INSPECT AMBIENT TEMPERATURE SENSOR
(a) Remove the ambient temperature sensor and disconnect
the A1 connector.
(b) Measure the resistance according to the value(s) in the
table below.
Standard:
Tester connectionConditionSpecified condition
A1-1 - A1-250F (10C)3.00 to 3.73 kW
A1-1 - A1-259F (15C)2.45 to 2.88 kW
A1-1 - A1-268F (20C)1.95 to 2.30 kW
A1-1 - A1-277F (25C)1.60 to 1.80 kW
A1-1 - A1-286F (30C)1.28 to 1.47 kW
A1-1 - A1-295F (35C)1.00 to 1.22 kW
A1-1 - A1-2104F (40C)0.80 to 1.00 kW
A1-1 - A1-211 3F (45C)0.65 to 0.85 kW
A1-1 - A1-2122F (50C)0.50 to 0.70 kW
A1-1 - A1-2131F (55C)0.44 to 0.60 kW
A1-1 - A1-2140F (60C)0.36 to 0.50 kW
HINT:
As the temperature increases, the resistance decreases (see
the chart below).
NOTICE:
Even slightly touching the sensor may change the resis-
tance value. Be sure to hold the connector of the sensor.
NG REPLACE AMBIENT TEMPERATURE SENSOR
OK
Page 858 of 2572
F46780
A1
Wire harness side:
E7
Wire harness side:
E2
TA ME6
05-760
- DIAGNOSTICSTIRE PRESSURE WARNING SYSTEM
950 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
5 CHECK HARNESS AND CONNECTOR(ECM - AMBIENT TEMPERATURE SENSOR)
(SEE PAGE 01-36)
(a) Disconnect the ECM E6 and E7 connectors.
(b) Measure the resistance according to the value(s) in the
table below.
Standard:
Tester connectionConditionSpecified condition
E6-32 (TAM) - A1-2AlwaysBelow 1 W
E7-28 (E2) - A1-1AlwaysBelow 1 W
E6-32 (TAM) - Body
groundAlways10 kW or higher
E7-28 (E2) - Body
groundAlways10 kW or higher
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
REPLACE ECM (SEE PAGE 10-9 OR 10-24)
Page 859 of 2572
I39166
C16
Steering Pad SW LH
AU1
AU2
EAU12
11
10GR
B
LIL13
R237
8
6SW1
SW2
GMD Radio Receiver Assy
R
LG
GRR23
R23 IL14
IL15 12
11
10 12
11
10AU1
AU2
EAUAU1
AU2
EAU A
Spiral Cable Sub-assy
- DIAGNOSTICSAUDIO SYSTEM
05-1643
1833 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
STEERING PAD SWITCH CIRCUIT
CIRCUIT DESCRIPTION
This circuit sends an operation signal from the steering pad switch to the radio receiver assy.
If there is an open in the circuit, the audio system cannot be operated by the steering pad switch.
If there is a short in the circuit, the same condition as that when the switch is continuously depressed occurs.
Therefore, the radio receiver assy cannot be operated by the steering pad switch, and also the radio receiver
assy itself does not function.
WIRING DIAGRAM
05IRM-01
Page 860 of 2572
I40203
R23
SW1
SW2GMD
05-1644
- DIAGNOSTICSAUDIO SYSTEM
1834 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
INSPECTION PROCEDURE
1 INSPECT RADIO RECEIVER ASSY
(a) Disconnect the connectors from the radio receiver assy.
(b) Measure the resistance according to the values in the
table below.
Standard:
Tester connectionConditionSpecified condition
SW1 - GMDDo not switch positionApprox. 100 kW
SW1 - GMDSEEK+ switch: pushApprox. 0 W
SW1 - GMDSEEK- switch: pushApprox. 0.3 kW
SW1 - GMDVOL+ switch: pushApprox. 1 kW
SW1 - GMDVOL- switch: pushApprox. 3.2 kW
SW2 - GMDDo not switch positionApprox. 100 kW
SW2 - GMDMODE switch: pushApprox. 0 W
NG Go to step 2
OK
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
(SEE PAGE 05-1632)
Page 861 of 2572
I39169
C16
AU1
AU2
EAU
- DIAGNOSTICSAUDIO SYSTEM
05-1645
1835 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
2 INSPECT STEERING PAD SWITCH LH(AU1,AU2,EAU)
(a) Disconnect the steering pad switch LH connector.
(b) Measure the resistance according to the values in the table below.
Standard:
Tester connectionConditionSpecified condition
AU1 - EAUDo not switch positionApprox. 100 kW
AU1 - EAUSEEK+ switch: pushApprox. 0 W
AU1 - EAUSEEK- switch: pushApprox. 0.3 kW
AU1 - EAUVOL+ switch: pushApprox. 1 kW
AU1 - EAUVOL- switch: pushApprox. 3.2 kW
AU2 - EAUDo not switch positionApprox. 100 kW
AU2 - EAUMODE switch: pushApprox. 0 W
NG REPLACE STEERING PAD SWITCH LH
(SEE PAGE 67-28)
OK
Page 862 of 2572
I40203
R23
SW1
SW2GMD
Radio Receiver Assy:
I36955I38235
Spiral Cable Side:
EAUAU2AU1
A
05-1646
- DIAGNOSTICSAUDIO SYSTEM
1836 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
3 CHECK HARNESS AND CONNECTOR(SPIRAL CABLE SUB-ASSY - RADIO
RECEIVER ASSY)
(a) Disconnect the connectors from the spiral cable sub-
assy and radio receiver assy R23.
(b) Measure the resistance according to the values in the
table below.
Standard:
Tester connectionSpecified condition
SW1 - AU1Below 1 W
SW2 - AU2Below 1 W
GMD - EAUBelow 1 W
SW1 - Body ground10 kW or higher
SW2 - Body ground10 kW or higher
GMD - Body ground10 kW or higher
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
REPLACE SPIRAL CABLE SUB-ASSY (SEE PAGE 60-26)
Page 863 of 2572
I36622
Stereo Component Amplifier AssyRadio Receiver Assy
MUTE12
BR5
IR2BR7
R4MUTE
S22
- DIAGNOSTICSAUDIO SYSTEM
05-1651
1841 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
AMP MUTE SIGNAL CIRCUIT (FROM RADIO RECEIVER ASSY)
CIRCUIT DESCRIPTION
This circuit sends the signal to the stereo component amplifier to mute the noise. Because of that, the noise
produced by changing the sound source ceases.
In addition, this circuit is used to mute the sound when the navigation system performs voice guide.
If the vehicle is equipped with a navigation system, normal audio sound will cease, and only voice guidance
will be heard from the driver's side speaker when voice guides are given.
If there is an open in the circuit, noise can be heard from the speaker when changing the sound source.
If there is a short in the circuit, even though the stereo component amplifier assy is normal, no sound or only
extremely small sound can be produced.
WIRING DIAGRAM
05IRO-01
Page 864 of 2572

I39177MUTES22
I39175I39178I40341
Radio Receiver Assy:
Stereo Component Amplifier Assy:MUTER4
MUTE
S22
05-1652
- DIAGNOSTICSAUDIO SYSTEM
1842 Author: Date:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
INSPECTION PROCEDURE
1 INSPECT STEREO COMPONENT AMPLIFIER ASSY
(a) Measure the voltage according to the value in the table
below.
Standard:
Tester connectionConditionSpecification
MUTE -Body ground
Turn ignition switch to
ACC, Audio system is
playing "Changing
Above 3.5 V " Below 1 V
NG Go to step 2
OK
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
(SEE PAGE 05-1632)
2 CHECK HARNESS AND CONNECTOR(RADIO RECEIVER ASSY - STEREO
COMPONENT AMPLIFIER ASSY)
(a) Disconnect the connectors from the radio receiver assy
and stereo component amplifier assy.
(b) Measure the resistance according to the values in the
table below.
Standard:
Tester connectionConditionSpecified condition
MUTE - MUTEAlwaysBelow 1 W
MUTE - Body groundAlways10 kW or higher
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK