Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Ecm power source circuit / Circuit description
Toyota Corolla (E120): Circuit description
When the ignition switch is turned on, battery positive voltage is applied to the coilwhich closes the contacts of the efi main relay (marked: efi) and supplies power to terminal +b of the ecm.
This signal causes current to flow to the coil, closing the contacts of the efi relay and supplying power to terminal +b of the ecm.
If the ignition switch is turned off, the ecm continues to switch on the efi relay for a maximum of 2 seconds for the initial setting of the isc valve.
Wiring diagram

Other materials:
Listening to a USB memory device
Connecting a USB memory device enables you to enjoy music from the vehicle
speakers.
Touch “USB” on the audio source selection screen.
Connecting a USB memory device
Audio control screen
Pressing the “AUDIO” button displays the audio control screen from any screens
of the selected so ...
Circuit description
The throttle position sensor is mounted in the throttle body and
detects the throttle valve opening angle.
When the throttle valve is fully closed, a voltage of approximately
0.3 To 1.0 V is applied to terminal vta of the ecm. The voltage
applied to terminal vta of the ecm increases in pro ...
Noise occurs
Inspection procedure
1 Check of speaker installation
Check speaker installation condition.
Check that each speaker is securely installed.
Standard: malfunction disappear.
Hint:
the radio is equipped with noise prevention system that does not work against
the regular use of t ...


