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)
Test yourself
A quick Toyota Sienna quiz: every answer comes with an explanation and a link to the manual page.