Toyota Sienna Service Manual: ECU Power Source Circuit
DESCRIPTION
This is the power source for the tire pressure warning ECU.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE: When replacing the tire pressure warning ECU, read the transmitter IDs stored in the old ECU using the intelligent tester and write them down before removal.
It is necessary to register an ID code after replacing the tire pressure warning valve and transmitter and/or the tire pressure warning ECU (See page TW-20).
1 INSPECT FUSE (ECU-IG)
(a) Remove the ECU-IG fuse from the instrument panel junction block.
(b) Measure the resistance of the fuse.
Standard resistance: Below 1 Ω
2 INSPECT IGNITION RELAY NO. 1
(a) Remove the IG1 relay from the instrument panel junction block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance 
3 CHECK HARNESS AND CONNECTOR (ECU - BATTERY AND BODY GROUND)
(a) Disconnect the T15 ECU connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage 
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE (See page TW-28)
Tire Pressure Warning Light Circuit
DESCRIPTION
If the ECU detects trouble, the tire pressure warning light blinks (comes on
after blinking for 1 minute) and
tire pressure monitor is cancelled at the same time. At this time, the ECU ...
TC and CG Terminal Circuit
DESCRIPTION
DTC output mode is set by connecting terminals 13 (TC) and 4 (CG) of the
DLC3. The DTCs are indicated
by blinks of the tire pressure warning light.
WIRING DIAGRAM
HINT:
When eac ...
Other materials:
Disassembly
1. REMOVE COOLER DRYER
(a) Using a hexagon wrench 14 mm (0.55 in.), remove
the cap from the modulator.
(b) Remove the O-ring from the cap.
(c) Using needle nose pliers, remove the cooler dryer. ...
Anti-glare function
Manual anti-glare inside rear view mirror
Reflected light from the headlights of vehicles behind can be reduced
by operating the lever.
Normal position
Anti-glare position
Auto anti-glare inside rear view mirror
Responding to the level of brightness of the headlights of veh ...
Removal
NOTICE:
Before removing the tire pressure warning ECU, read the
registered transmitter IDs of all wheels and write them
down to use for re-registration of transmitter IDs (See
page TW-20).
1. DISCONNECT CABLE FROM NEGATIVE BATTERY
TERMINAL
CAUTION:
Wait at least 90 seconds after dis ...
