Pro form 550s only runs for 1/2 second and shuts itself off!

The Motor controller board is faulty. That's why its runs on the Top speed and and shut sown due to the over current consumption
You have to replace the motor driver or get it repaired.
If you wish to get some details; visit the site linked here. Pull up older posts. http://electro-medical.blogspot.com/

This answer is correct. 4/12 divided by 2/2= 1/3
The reciprocal of 2/2 is 2/2
Then you multiply straight across and reduce to get 1/3

please see my personal TIPS and fix it. However see the video .God bless you

check and see if the heater has a high temperature limit switch. if it does it will shut the machine off until it cools down.. just replace it with a new one.

You may need to calibrate the incline. Do this with the following procedure.
Safety key out
press the stop and speed up buttons at the same time while inserting the safety key. (you are now in diagnostics)
press the stop button one time only.
now press the incline up button (incline motor should start moving up)
incline will go up to the top and then all the way to the bottom. when it gets done you can remove the key. Reinsert the key and you should be operating normally.
Good luck Tim

change drive belt proform xp 550s treadmill

This sounds like you will need to replace the thermostat!
That should fix this common problem!

We are having the same problem of the Pioneer Elite Pro-99 turning itself off all of a sudden. The red 'non' power button comes on as if we had turned it off remotely.
We would love to resolve this. If you can help let us know.

Take it into a repair shop and say a capacitor has gone. It isn't a big job.
The part itself is a couple of $

BAD NEWS THE PICTURE TUBE IS WEAK THE ONLY FIX IS TO REPLACE YOUR MONITOR WITH A NEW ONE