Toyota Sienna Service Manual: Back-up Power Source Circuit
DESCRIPTION
This is the back-up power source for the A/C amplifier. Power is supplied even when the ignition switch is off and is used for diagnostic trouble code memory, etc.
WIRING DIAGRAM
INSPECTION PROCEDURE
1 INSPECT FUSE (ECU-B)
(a) Remove the ECU-B fuse from the engine room junction block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance
2 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
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
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:
Catalyst System Efficiency Below Threshold
MONITOR DESCRIPTION
The ECM uses the sensors mounted in front of and behind the three-way
catalyst (TWC) to monitor its
efficiency. The first sensor, an Air Fuel ratio (A/F) sensor, sends pre-catalyst
A/F ratio information to the
ECM. The second sensor, a heated oxygen sensor (O2S), sends ...
Warning lights
Warning lights inform the driver of malfunctions in the indicated vehicle’s
systems.
*1: These lights turn on when the engine switch is turned to the “ON”
position
(vehicles without a smart key system) or IGNITION ON mode (vehicles
with a smart key system) to indicate that a system c ...
ECM Power Source Circuit
DESCRIPTION
When the ignition switch is turned to the ON position, the battery voltage is
applied to terminal IGSW of
the ECM. The ECM MREL output signal causes a current to flow to the coil,
closing the contacts of the EFI
relay and supplying power to terminal +B of the ECM.
If the igniti ...
