Toyota Corolla (E120): Circuit description
When driving uphill under cruise control, in order to reduce the number of shifting due to on–off overdrive operation and to provide smooth driving, when down shifting in the electronically controlled transmission occurs, a signal to prevent upshift until the end of the uphill slope is sent from the cruise control ecu assy to the electronically controlled transmission.
Terminal ect of the cruise control ecu assy detects the shift change signal (output to electronically controlled transmission no.2 Solenoid) from the ecm.
If the vehicle slows down, also when terminal ect of the cruise control ecu assy receives down shifting signal, it sends a signal from terminal od to ecm to cut overdrive until the end of the uphill slope, and the number of gear shifts are reduced and gear shift points in the electronically controlled transmission are changed.
Wiring diagram

Other materials:
Inspection procedure
Hand–held tester:
1 Perform active test by hand–held tester(operation of circuit
opening relay)
Connect the hand–held tester to the dlc3.
turn the ignition switch on and push the hand–held tester main
switch on.
select the item ”diagnosis / enhanced obd ii / active ...
Manual transmission/transaxle
Preparation
Sst
Equipment
Lubricant
...
Inspection
1. Cooling fan relay
Inspect the cooling fan relay continuity.
Using an ohmmeter, check that there is continuity
between terminals 1 and 2.
If there is no continuity, replace the relay.
Check that there is no continuity between terminals
3 and 5.
If there is conti ...


