TOYOTA SEQUOIA 2001 Service Repair Manual

I28476
R6
Light Control
Rheostat AssyRadio Receiver Assy
J/C
Steering Pad Switch
Spiral Cable
Sub±assy From
TAILLIGHT
RelayILL±
GND J/C
ILL+ W±G
GJ39 J40
J39 J40
J39 J40R4
R19 R4R3
R2 W±G
G
G
G A B
A
AAB
ILL±
T12
5
2
10
6 A±1
A±10C9±1
BR±W C9±10(*1)
*1: Separate Type Amplifier
*2: Built±in Type Amplifier(*2) (*1) (*2)
6
4
± DIAGNOSTICSAUDIO SYSTEM
DI±1999
2193 Author: Date:
2005 SEQUOIA (RM1146U)
Illumination circuit
CIRCUIT DESCRIPTION
Power is supplied to the radio receiver panel illumination when the light control switch is in the TAIL or HEAD
position. The body ECU determines the external brightness based on the brightness level detected by the
automatic light control sensor, and then operates the tail relay. Power can also be supplied by operating the
relay.
The intensity of the radio receiver panel illumination can be adjusted by the rheostat switch.
WIRING DIAGRAM
DID9X±01

DI±2000
± DIAGNOSTICSAUDIO SYSTEM
2194 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
NOTICE:
The vehicle is equipped with SRS (Supplemental Restraint System) such as airbags. Before servic-
ing (including removal or installation of parts), be sure to read the precautionary notice for the sup-
plemental restraint system (See page RS±1).
1 Check illumination.
CHECK:
Check if the illumination for the radio receiver assy, steering pad switch assy or others (A/C switch, cigarette
lighter, etc.) comes on when the light control switch is turned to the HEAD or TAIL position.
RESULT:
Components with illuminationGo to step
Illumination comes on for all components except radio receiver assy.A
Illumination comes on for all components except steering pad switch does not
come on.B
Illumination comes on for all components except radio receiver assy, steering
pad switch, Rear heater control panel, each switch, etc.C
All illumination does not come on. (Radio receiver assy, steering pad switch,
Combination meter, Rear heater control panel, each switch, etc.)D
HINT:
If the illuminations have malfunctions, check the rheostat switch.
B Go to step 4.
C Go to step 8.
D Go to combination meter system
(See page DI±1645).
A

I28739
Separate Type Amplifier
Wire Harness View:
R4
ILL+
I28743
Built±in Type Amplifier
Wire Harness View:
R2
ILL+
± DIAGNOSTICSAUDIO SYSTEM
DI±2001
2195 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check radio receiver assy (ILL+).
PREPARATION:
Disconnect the radio receiver assy connector.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Symbol
(Tester connection)ConditionSpecified condition
ILL+ (R2±10) ±
Body ground (*2)Light control switch TAIL10 to 14 V
ILL+ (R4±2) ±
Body ground (*1)Light control switch TAIL10 to 14 V
*1: Separate Type Amplifier
*2: Built±in Type Amplifier
NG Repair or replace harness or connector
(Radio receiver assy ± battery).
OK

I28739
Separate Type Amplifier
Wire Harness View:
ILL±
R4
I28744
Built±in Type Amplifier
Wire Harness View:
R3
ILL±
I28577
Light Control Rheostat
Wire Harness View:
R6
ILL±
DI±2002
± DIAGNOSTICSAUDIO SYSTEM
2196 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check harness and connector (Radio receiver assy ± Light control rheostat).
PREPARATION:
Disconnect the radio receiver assy connector and light control
rheostat connector.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Symbol (Tester connection)Specified condition
ILL± (R3±5) ± ILL± (R6±6) (*2)Below 1 W
ILL± (R4±12) ± ILL± (R6±6) (*1)Below 1 W
ILL± (R6±6) ± Body ground (*1)10 kW or higher
*1: Separate Type Amplifier
*2: Built±in Type Amplifier
NG Repair or replace harness or connector.
OK
Replace radio receiver assy.

I28741
Separate Type Amplifier
Wire Harness View:
R19
GND
I28745
Built±in Type Amplifier
Wire Harness View:
R19
GND
± DIAGNOSTICSAUDIO SYSTEM
DI±2003
2197 Author: Date:
2005 SEQUOIA (RM1146U)
4 Check radio receiver assy.
PREPARATION:
Disconnect the radio receiver assy connector.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Symbol
(Tester connection)ConditionSpecified condition
GND (R19±6) ±
Body groundLight control switch TAIL10 to 14 V
OK Replace radio receiver assy.
NG

I28296
1
10
DI±2004
± DIAGNOSTICSAUDIO SYSTEM
2198 Author: Date:
2005 SEQUOIA (RM1146U)
5 Inspect steering pad switch assy.
PREPARATION:
(a) Disconnect the steering pad switch connector.
(b) Connect the positive (+) lead to terminal 1 and the negative (±) lead to terminal 10 of steering pad
switch assy connector.
CHECK:
Check if the illumination for the steering pad switch assy comes on.
OK:
Illumination for the steering pad switch assy comes on.
NG Replace steering pad switch assy.
OK

I28295
Vehicle Side:
Steering Pad Switch Assy Side:
C9
A
± DIAGNOSTICSAUDIO SYSTEM
DI±2005
2199 Author: Date:
2005 SEQUOIA (RM1146U)
6 Inspect spiral cable sub±assy.
PREPARATION:
Remove the spiral cable sub±assy.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Tester connectionConditionSpecified condition
A±1 ± C9±1AlwaysBelow 1 W
A±10 ± C9±10AlwaysBelow 1 W
NG Replace spiral cable sub±assy.
OK

I28741
Separate Type Amplifier
Wire Harness View:
R19
GND
I28745
Built±in Type Amplifier
Wire Harness View:
R19
GND
I28294
Spiral Cable Sub±assy
Connector Front View:
C9
DI±2006
± DIAGNOSTICSAUDIO SYSTEM
2200 Author: Date:
2005 SEQUOIA (RM1146U)
7 Check harness and connector (Radio receiver assy ± Spiral cable sub±assy).
PREPARATION:
Disconnect the spiral cable sub±assy connector.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Symbol
(Tester connection)ConditionSpecified condition
GND (R19±6) ±
Spiral cable terminal 10AlwaysBelow 1 W
GND (R19±6) ±
Body groundAlways10 kW or higher
NG Repair or replace wire harness or connector
(Radio receiver assy ± spiral cable sub±assy).
OK
Repair or replace wire harness or connector (Battery ± spiral cable sub±assy).

I28576
270°
Bright
0°
DarkR6
ILL±
I28577
Light Control Rheostat
Wire Harness View:
R6
E
± DIAGNOSTICSAUDIO SYSTEM
DI±2007
2201 Author: Date:
2005 SEQUOIA (RM1146U)
8 Check light control rheostat.
PREPARATION:
(a) Reconnect the light control rheostat switch connector.
(b) Ignition switch is ON.
(c) Light control switch is TAIL or HEAD.
CHECK:
Measure the voltage according to the value(s) in the table be-
low.
OK:
Symbol
(Tester connection)ConditionSpecified condition
ILL± (R6±6) ±
Body groundRheostat knob to fully
counterclockwise "
fully clockwise
Below 1 V " 10 to 14 V
NG Replace light control rheostat.
OK
9 Check harness and connector (Light control rheostat ± Body ground).
PREPARATION:
Disconnect the light control rheostat connector.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:
Symbol (Tester connection)Specified condition
E (R6±5) ± Body groundBelow 1 W
NG Repair or replace harness or connector.
OK
Repair or replace wire harness or connector (Battery ± spiral cable sub±assy).

I28378
Radio Receiver Assy
R±W 17
R4
MUTE S10
Stereo Component Amplifier
MUTE DI±2008
± DIAGNOSTICSAUDIO SYSTEM
2202 Author: Date:
2005 SEQUOIA (RM1146U)
Mute signal circuit
CIRCUIT DESCRIPTION
This circuit sends a signal to the stereo component amplifier to mute noise. Because of that, the noise pro-
duced by changing the sound source ceases.
If there is an open in the circuit, noise can be heard from the speakers 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
an extremely small sound can be produced.
WIRING DIAGRAM
DID9Y±01