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:
Diagnosis system
DESCRIPTION
(a) When troubleshooting OBD II (On-Board
Diagnostics) vehicles, an intelligent tester
(complying with SAE J1987) must be connected to
the DLC3 (Data Link Connector 3) of the vehicle.
Various data in the vehicle's ECM (Engine Control
Module) can be then read.
(b) OBD II regu ...
Customize parameters
HINT:
The following items can be customized.
NOTICE:
After confirming whether the items requested by the
customer are applicable or not for customization,
perform the customize operation.
Be sure to record the current settings before
customizing.
When troubleshooting, make sure that ...
Terminals of ECU
1. CHECK DISTANCE CONTROL ECU
Reference: waveform 1
HINT:
Terminal: LRDD - SGND
Gauge set: 2 V/DIV., 10 ms./DIV.
Condition: ignition switch in the ON position
Reference: waveform 2
HINT:
Terminal: LRRD - SGND
Gauge set: 2 V/ ...
