Treadmill stop then display an error speed

Please see a handy diagnostic test mode guide here:

http://www.treadmillsrepair.co.uk/2014/07/diagnostic-test-modes.html

If the is a Next Gen unit need to enter Diagnostic menu by pressing and holding pause then press clear twice. Continue to hold pause until until read service menu. press any arrow up and select system test ,then press enter the display will begin to automatically scroll thru available options. press enter to access Main Motor Module the next window will be Speed Automatic.
Upon entering this test mode you will able to check the drive motor and motor control board. By using the the speed arrows you will be able see the actual speed if functioning if not it could possibly be the speed sensor or wire harness ( SIMPLE CONTINUITY CHECK WILL RULE IN OR OUT THE HARNESS ) and point the problem. Now if their is no belt movement then hit clear and proceed over to SPEED CONTROL ERRORS hit enter this test allows seeing the motor controller conditions that are being displayed on the motor controller display if any of these come up then the controller need s to repair or replaced:
Max Temperature, Maximum voltage, Fault Line 1 error, Static current trip and dynamic current trip ( this also can a running belt tension this can result in a cannot obtain speed error message ) hit clear to get out of diagnostic once you eliminated the problem. Good Luck!!!