Toyota Sequoia (2005). Manual - part 550

I28501

Steering 
Pad Switch

Spiral Cable 
Sub–assy

Radio Receiver Assy

SW2

GND

SW1

R19

EAU

AU2

R19

R19

AU1

EAU

AU2

AU1

C9–11

GR–R

LG–R

BR–W

C9–12

C9–10

A–11

A–12

A–10

8

7

6

–

DIAGNOSTICS

AUDIO SYSTEM

DI–1995

2189

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 when the switch is continuously depressed occurs.
Therefore, not only the steering pad switch cannot operate the radio receiver assy, but also the radio receiver
assy itself cannot function.

WIRING DIAGRAM

DID9W–01

I28741

SW2

SW1

GND

R19

Separate Type Amplifier 
Wire Harness View:

I28745

R19

SW2

SW1

GND

Built–in Type Amplifier 
Wire Harness View:

DI–1996

–

DIAGNOSTICS

AUDIO SYSTEM

2190

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

Inspect steering pad switch assy.

PREPARATION:
Disconnect the radio receiver assy connector.
CHECK:
Measure the resistance according to the value(s) in the table
below.
OK:

Symbol

(Tester connection)

Condition

Specified condition

SW1 (R19–7) – 

GND (R19–6)

No switch is pushed

Approx. 100 k

Ω

SW1 (R19–7) – 

GND (R19–6)

SEEK+ switch: push

Approx. 0 

Ω

SW1 (R19–7) – 

GND (R19–6)

SEEK– switch: push

Approx. 0.3 k

Ω

SW1 (R19–7) – 

GND (R19–6)

VOL+ switch: push

Approx. 1 k

Ω

SW1 (R19–7) – 

GND (R19–6)

VOL– switch: push

Approx. 3.2 k

Ω

SW2 (R19–8) – 

GND (R19–6)

No switch is pushed

Approx. 100 k

Ω

SW2 (R19–8) – 

GND (R19–6)

MODE switch: push

Approx. 0 

Ω

NG

Go to step 2.

OK

Proceed to next circuit inspection shown in problem symptoms table (See page 

DI–1967

).

I28724

EAU

AU2

AU1

Connector Front View:

–

DIAGNOSTICS

AUDIO SYSTEM

DI–1997

2191

2

Inspect steering pad switch assy.

PREPARATION:
Disconnect the steering pad switch assy connector.
CHECK:
Measure the resistance according to the value(s) in the table below.
OK:

Symbol (Tester connection)

Condition

Specified condition

AU1 (A–12) – EAU (A–10)

No switch is pushed

Approx. 100 k

Ω

AU1 (A–12) – EAU (A–10)

SEEK+ switch: push

Approx. 0 

Ω

AU1 (A–12) – EAU (A–10)

SEEK– switch: push

Approx. 0.3 k

Ω

AU1 (A–12) – EAU (A–10)

VOL+ switch: push

Approx. 1 k

Ω

AU1 (A–12) – EAU (A–10)

VOL– switch: push

Approx. 3.2 k

Ω

AU2 (A–11) – EAU (A–10)

No switch is pushed

Approx. 100 k

Ω

AU2 (A–11) – EAU (A–10)

MODE switch: push

Approx. 0 

Ω

NG

Replace steering pad switch assy.

OK

I28340

Steering Pad Switch Assy Side:

EAU

AU2

AU1

Vehicle Side:

EAU

AU2

AU1

C9

A

DI–1998

–

DIAGNOSTICS

AUDIO SYSTEM

2192

3

Inspect spiral cable sub–assy.

PREPARATION:
Disconnect the spiral cable sub–assy connector.
CHECK:
Measure the resistance according to the values in the table be-
low.
OK:

Symbol (Tester connection)

Specified condition

EAU (A–10) – EAU (A–10)

Below 1 

Ω

AU1 (A–12) – AU1 (A–12)

Below 1 

Ω

AU2 (A–11) – AU2 (A–11)

Below 1 

Ω

NG

Replace spiral cable sub–assy.

OK

Repair or replace harness or connector (Radio receiver assy – spiral cable).