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:
Illumination Circuit
DESCRIPTION
Power is supplied to the radio and navigation assembly and steering pad
switch illumination when the
light control switch is in the TAIL or HEAD position.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
The vehicle is equipped with an SRS (Supplemental Restraint System) such as t ...
Terminals of ECU
1. CHECK INSTRUMENT PANEL J/B ASSEMBLY
(MULTIPLEX NETWORK BODY ECU)
Disconnect the B6, B7 and B9 ECU connectors.
Disconnect the 1A, 1C, 1L and 1K J/B connectors.
Measure the voltage and resistance between each
terminal of the wire harness side connectors and
body gro ...
Disassembly
1. REMOVE STOP LIGHT SWITCH ASSEMBLY
(a) Turn the stop light switch assembly
counterclockwise and remove the stop light switch
assembly.
(b) Remove the stop light switch mounting adjuster
from the brake pedal support sub-assembly.
2. REMOVE STOP LIGHT SWITCH CUSHION
(a) Remove the stop ligh ...
