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:
Malfunction in speedometer
Wiring diagram
Inspection procedure
1 Check combination meter assy
Remove the combination meter assy with connector still
connected.
check voltage.
Jack up either of the front wheels.
Shift the shift lever to neutral.
Turn the ignition switch to on ...
Inspection
1. Thermostat
Hint:
the thermostat is numbered with the valve opening temperature.
Immerse the thermostat in water and gradually heat the
water.
check the valve opening temperature.
Valve opening temperature:
80 to 84 c (176 to 183 f)
Hint:
if the valve opening temperatur ...
Circuit description
Shifting from 1st to o/d is performed in combination with on and off of the
shift solenoid valve s1 and s2
controlled by ecm. If an open or short circuit occurs in either of the solenoid
valves, the ecm controls the
remaining normal solenoid valve to allow the vehicle to be operated smoothly
...


