Cruise control works intermittently

it sounds like the cruise control ECU has gone bad. here is the location so you can try replacing it. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

With respect sir, I really want the Toyota Service Manual troubleshooting procedure before that can be determined. I have a Toyota Engine Service Manual but it has no info on troubleshooting the Cruise control circuitry. What does the blinking (5) times mean? PC?

The blinking light means there is an operational l error. This guide can show you how to get the codes:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is the factory testing procedures. Check out the diagrams (below). Please let us know what you find.

Thank you. I will be in touch with my diagnosis.

Hello Ken, upon further testing of the Cruise Control System, I've uncovered a very simple but illusive type problem. The switch on the column is the culprit. I did two separate experiments with the switch. First I press down on the lever to activate the Cruise Control like I would normally, using a moderate amount of force, which failed the test (error code). Second, I press the lever down with liberal force and the test passed every time. The contacts inside the mechanical switch are dirty (not making good contact) or it is a defective switch.

Good find! here is a picture and description of the switch.

Cruise ON-OFF switch is power switch for cruise control system. When ignition is turned off, cruise ON-OFF switch is also turned off. Switch remains off even when ignition is turned on again.

SET/COAST Position
With cruise ON-OFF switch on, and vehicle speed greater than 25 MPH, set cruise control switch to SET/COAST position and release switch. CC ECU will store and constantly control vehicle speed.

While in cruise control mode, if cruise control switch is set and held in SET/COAST position, actuator will be energized. Engine throttle valve will close, and vehicle will decelerate until switch is released. From then on, CC ECU will store and constantly control new vehicle speed. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.