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:
Transmission Range Sensor Circuit Malfunction (PRNDL Input)
DESCRIPTION
The park/neutral position switch detects the shift lever position and sends
signals to the ECM.
HINT:
After confirming DTC P0705, use the intelligent tester to confirm the PNP
switch signal in the ALL menu
(to reach the ALL menu: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ...
Precaution
Keep in mind the following points when inspecting the
dynamic laser cruise control system.
As there is a limitation on the vehicle-to-vehicle distance
controlling capability, do not overly rely on the dynamic
laser cruise control system.
Do not neglect to pay constant attentio ...
Front Occupant Classification Sensor LH Circuit
Malfunction
DTC B1780 Front Occupant Classification Sensor LH Circuit
Malfunction
DESCRIPTION
The front occupant classification sensor LH circuit consists of the occupant
classification ECU and the
front occupant classification sensor LH.
DTC B1780 is recorded when a malfunction is detected in the fron ...