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:
Circuit description
This circuit turns on the magnetic clutch inside the actuator during cruise
control operation according to the
signal from the ecu. If a malfunction occurs in the actuator or speed sensor,
etc. During cruise control operation,
the rotor shaft between the motor and control plate is released.
...
How to proceed with troubleshooting
1 Vehicle brought to workshop
2 Customer problem analysis
3 Check and clear dtcs and freeze frame data
4 Problem symptom confirmation
Symptom does not occur: go to
step 5
Symptom occurs: go to step 6
5 Symptom simulation
6 Dtc check
There is no
output: go to step 7
There is outp ...
Replacement
Hint:
installation is in the reverse order of the removal. But the installation is
indicated only when it has a point.
1. Remove rear door opening trim rh
2. Remove rear door opening trim lh
3. Remove rear seat cushion assembly ( or 72–8)
4. Remove rear seat back assy (fixed type rear seat) ...


