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:
Active head restraints
When the occupant’s lower back
presses against the seatback during
a rear-end collision, the head
restraint moves slightly forward
and upward to help reduce the
risk of whiplash on the seat occupant
Active head restraints
Even small forces applied to the seatback may cause the head rest ...
System normal condition check
1. CHECK NORMAL CONDITION
If the symptom is applicable to any of the following,
it is intended behavior, and not a malfunction.
Symptom
Answer
A longer route than expected is chosen.
Depending on the road conditions, the radio and navigation assembly
m ...
Diagnosis system
1. CHECK DLC3
(a) The vehicle's ECM uses the ISO 15765-4 for
communication. The terminal arrangement of the
DLC3 complies with SAE J1962 and matches the
ISO 15765-4 format.
HINT:
Connect the cable of the intelligent tester to the
DLC3, turn the ignition switch to the ON position
and atte ...
