Toyota RAV4 (XA40) 2013-2018 Service Manual: Back-up power source circuit
Description
This is the back-up power source circuit for the air conditioning amplifier. Power is supplied even when the ignition switch is turned off and is used for functions such as the diagnostic trouble code memory.
wiring diagram
Inspection procedure
- Inspect fuse (ecu-b2)
- Remove the ecu-b2 fuse from the engine room no. 2 Relay block.
- Measure the resistance of the fuse.
Standard resistance:
below 1 
- Check wire harness (air conditioning amplifier - battery)
- Disconnect the e37 amplifier connector.
- Measure the voltage of the wire harness side connector.
Standard voltage
- Check wire harness (air conditioning amplifier - body ground)
- Disconnect the e37 amplifier connector.
- Measure the resistance of the wire harness side connector.
Standard resistance
Proceed to next circuit inspection shown in problem symptoms table
Ig power source circuit
Description
This is the main power source supplied to the air conditioning amplifier when
the ignition switch is on
(ig). This power source is used for operating components, such as the air
cond ...
Other materials:
Engine (ignition) switch
(vehicles without smart
key system)
Starting the engine
1. Pull the parking brake switch
to check that the parking
brake is set.
The parking brake indicator will
come on.
2. Check that the shift lever is
set in P.
3. Firmly depress the brake
pedal.
4. Turn the engine switch to
START to start the engine.
â– If the engine does not s ...
Ecm power source circuit
Description
When the ignition switch is turned on, the battery voltage is applied to the
igsw of the ecm. The output
signal from the mrel terminal of the ecm causes a current to flow to the coil,
closing the contacts of the
integration relay (efi main relay) and supplying power to either term ...
On-vehicle inspection
Check throttle body
Check the throttle control motor operating sounds.
Turn the ignition switch on.
When pressing the accelerator pedal, check
the operating sound of the running motor. Make
sure that no friction noises emit from the motor.
If friction noise exists, replace t ...
