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:
Purpose of readiness tests
The On-Board Diagnostic (OBD II) system is
designed to monitor the performance of emissionrelated
components, and indicate any detected
abnormalities with DTCs (Diagnostic Trouble Codes).
Since various components need to be monitored in
different driving conditions, the OBD II system ...
Description of code registration
It is necessary to register the transmitter ID in the tire
pressure warning ECU when replacing the tire pressure
warning valve and transmitter and/or tire pressure
warning ECU.
(a) Before registration
(1) In case of tire pressure warning ECU
replacement.
Read the registered transmitter I ...
Shifting the shift lever
While the engine switch is in the
“ON” position (vehicles without a
smart key system) or IGNITION ON mode (vehicles with a smart
key system), move the shift lever with the brake pedal
depressed.
When shifting the shift lever between P and D, make sure that the vehicle
is completely ...
