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:
Radio Broadcast cannot be Received or Poor Reception
INSPECTION PROCEDURE
1 CHECK RADIO RECEIVER
Check the radio's automatic station search function.
Check the radio's automatic station search function
by activating it.
OK:
The radio's automatic station search function
works properly.
2 CONFIRM MODEL
Result
3 INSPECT RADIO ...
Diagnosis system
1. CHECK DLC3
The ECU uses the ISO 15765-4 for communication
protocol. The terminal arrangement of the DLC3
complies with SAE J1962 and matches the ISO
15765-4 format.
NOTICE:
*: Before measuring the resistance, leave the
vehicle as is for at least 1 minute and do not
ope ...
Removal
1. REMOVE V-BANK COVER SUB-ASSEMBLY (See
page EM-28)
2. DISCONNECT VENTILATION HOSE
(a) Disconnect the ventilation hose from the ventilation
valve.
3. REMOVE VENTILATION VALVE
(a) Remove the ventilation valve. ...
