The belt on treadmill will rull at full speed, can't shut it down without turning it off.

Here are some possible causes and solutions:

Overheating: If the motor or electronics of the treadmill get too hot, the machine may shut down to prevent damage. Make sure that the treadmill is placed in a well-ventilated area and that the air filters are clean. You can also try lubricating the walking belt to reduce friction.

Faulty speed sensor: If the speed sensor is malfunctioning, it may cause the treadmill to shut down. You can try cleaning the speed sensor with a soft cloth and see if that helps .

Worn walking belt: If the walking belt is worn or damaged, it may cause the treadmill to shut down. You can try replacing the walking belt and see if that helps.

Electrical issues: If there are any electrical issues with the treadmill, it may cause the machine to shut down. You can try resetting the circuit breaker or unplugging the treadmill for a few minutes and then plugging it back in.

If none of these solutions work, it may be best to contact Proform customer service.

With belt movement check speed sensor. Without belt movement check MCB. If you neglected unit it could be belt and deck if its shutting down during a workout. I have also see a lot of on/ off switches getting old and causing LS errors due to low voltage to MCB

It shuts down because it does not recognize speed , check the speed sensor, depending on the model it's probably located next to front roller pulley
Good luck

here is a troubleshooting guide from Treadmill Doctor. Hope this helps

http://www.treadmilldoctor.com/Full-Speed-Upon-Power-Up-kf?utm_source=fixya&utm_medium=CPC&utm_campaign=Mendi

Dear Sir:

Thank you by your request. I hope everything is o.k

Now I will try to help you.

You have electrical-mechanical Problem:

If you can walk on your treadmill but it shuts down during a workout, it is normally caused by a friction problem with the belt and deck.
Here are the most common symptoms and solutions:
Symptom: The treadmill operates for a given period of time and the circuit breaker on the treadmill trips causing you to have to reset the breaker, or let it cool off then reset the breaker. The
amount of time required to shut down will progressively get shorter.
Solution: The walking belt is worn. The incline test is the best test for it if you don't have a way to take a
DC amp draw. Put the treadmill at full incline and walk normally. If it takes it longer to shut off or does not
shut off at all, you need to replace the walking belt. Be sure to inspect the deck for wear too. If you want to
go for a cheap fix try lubricating the walking belt. The best fix is to replace the
walking belt and then regularly maintain it and keep the treadmill clean.

Symptom: The treadmill will show power but after a given period of time, the treadmill will simply shut
down. Once you let it cool off, you can restart it back up but it shuts down faster and the time required
before it shuts down gets progressively shorter.
Solution: Your treadmill is most likely equipped with a heat sensor which shuts down the motor and/or
electronics to prevent them from burning up. If this is the case, replace the walking belt. Be sure to inspect
the deck for wear too. If you want to go for a cheap fix (that we don't recommend) try lubricating the walking
belt. The best fix is to replace the walking belt and then regularly maintain it and keep the treadmill clean.

Symptom: The treadmill shuts down in an intermittent pattern...there is no rhyme or reason to when it will
shut down. I get an error code or nothing shows up on the panel. I have to either unplug the treadmill or
reset it to restart the treadmill.
Solution: If you get an error code, contact us with the code and make and model and we will try to help
you figure out what is going on. Typically we either find a loose wire, an intermittent short, a bad power
board, or a bad control panel in service calls that we do locally. Unplug your treadmill and then check all
your wiring to make sure nothing is pinched, crimped or loose. Remove and replace each connector in
case corrosion is causing the problem. If the problem persists, you most likely have a bad control panel or
some call it a console.

Thank you in advance, sincerely. God bless you.

If you need additional Help , please contact me.

E.CUADRA
MANAGUA, NICARAGUA. C.A.

This condition is when the treadmill goes to full speed as soon as you power up the treadmill. Typically when this occurs, it is an indication of a short circuit in the motor controller.

You may have a beltand deck problem. Test by the following procedure:
without the poweron stand on the walking belt, push the belt in the, direction it normally turns. If the belt is very difficult to turn (on most treadmill this means that you have high belt/deck friction I first apply silicone lubricant between the belt & deck to see if that clears up the problem. Most problems originate from the belt and deck 75 to 85% of the time

Press the Stop and the Speed Up keys down while inserting the safety key this will get the into calibration mode. The next step is to press the Stop key one time. The Time window should read EP:2P. Some newer models may also say FP, Pass, or the like. This means that it passes the EPROM test. if it says 2F, FF or Fail then the upper console needs to be replaced
Press either incline key and the incline will calibrate automatically.
BE CAREFUL, THE TREADMILL WILL RUN AT FULL SPEED IN THIS NEXT MODE! DO NOT STAND ON THE WALKING BELT. Press the Speed Up key and hold it down until 85 is shown in the Distance window (some models may show the 85 number in another window
If the belt does not move in this mode then the controller board is defective and needs be replace.

This definitely sounds like the drive motor. One way to check is to remove the drive belt and run the motor without the walk belt connected. Obviously if you still have the noise it will be a motor issue. If not then it will be one of the 2 rollers. Good Luck! Tim

Did the shop only do a continuity check or a real load test with amp check also? Motors can look good and run with no load but fail under load.