Toyota Sienna Service Manual: IG Power Source Circuit
DESCRIPTION
The main power source is supplied to the A/C amplifier when the ignition switch is turned to the ON position.
The power source is used for operating the A/C amplifier and servo motor, etc.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT: Start the engine before inspection. Check the IG1 relay or battery if the engine does not start.
1 INSPECT FUSE (HTR)
(a) Remove the HTR fuse from the driver side junction block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance 
2 INSPECT A/C AMPLIFIER (IG - GND)
(a) Remove the A/C amplifier with its connectors still connected.
(b) Turn the ignition switch to the ON position.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage 
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
3 CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - BATTERY)
(a) Disconnect the connector from the A/C amplifier.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage
4 CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - BODY GROUND)
(a) Measure the resistance according to the value(s) in the table below.
Standard resistance 
REPLACE A/C AMPLIFIER
Rear Blower Motor Circuit
DESCRIPTION
Power to the rear blower motor is supplied from the battery via the RR A/C
relay.
The rear blower motor speed level varies between 0 and 31 based on the voltage
difference measured ...
ACC Power Source Circuit
DESCRIPTION
This circuit supplies power to the A/C amplifier and the illumination for the
clock.
WIRING DIAGRAM
INSPECTION PROCEDURE
1 INSPECT FUSE (ECU ACC)
(a) Remove the ECU ACC fuse fr ...
Other materials:
Mute Signal Circuit between Radio and Navigation Assembly and
Stereo Component Amplifier
DESCRIPTION
This circuit sends a signal to the stereo component amplifier to mute noise.
Because of that, the noise
produced 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 i ...
Other functions
Switching between outside air and recirculated air modes
Press .
The mode switches between outside air mode (
appears on the
display) and recirculated air mode (
appears on the display) each
time the button is pressed.
Defogging the windshield
Defoggers are used to defog the windshield a ...
Checking tires
Check if the treadwear indicators are showing on the tires. Also check
the tires for uneven wear, such as excessive wear on one side of the
tread. Check the spare tire condition and pressure if not rotated.
New tread
Worn tread
Treadwear indicator
The location of treadwear indicator ...
