Troubleshooting No Display on Stairmaster Stepper, 4400CL and 4600CL

Here we discuss the causes and how to troubleshoot a 'no display' issue on the Stairmaster stepper models 4600CL and 4400CL. Learn why your unit is not powering up.

A common misconception about battery-powered units is that they only require you to step on the pedals to power the console. The speed sensor plays a major role in powering the console.

If you step on the pedals and they fall to the floor due to the console not powering up so there is no resistance, you should check the speed sensor and the battery.

Tools Needed:

  • Voltmeter
  • 7/16" Wrench


  1. Test the battery voltage.
    1. Set your voltmeter to read DC voltage (if your meter has ranges, use a range appropriate for the 6-volt battery being tested).
    2. Place your voltmeter leads to the battery terminals and have an assistant step on the pedals.
      1. The reading should be above 6 VDC. (If your reading is negative, reverse your meter leads)
      2. If the battery voltage is below 6 VDC, it should be recharged or replaced.
  2. The speed sensor is mounted to the alternator and reads the speed sensor disc when the unit is pedaled producing an AC voltage. The voltage from the speed sensor can be tested at the connection of the speed sensor to the lower control board. The connection is a red and black wire.
    1. Using AC setting on your voltmeter at its lowest range, place the red lead to the red wire and the black lead to the black wire.
    2. Make sure the leads of the voltmeter are making a good connection.
    3. Now step on the unit and verify the voltage from the speed sensor.
      1. A good speed sensor will produce about 3 VAC before the console powers up.
      2. If the voltage is not correct, inspect the adjustment of the speed sensor.
        1. It may be necessary to adjust the sensor closer to the speed sensor disc. The proper gap of the speed sensor to the disc is about the thickness of a business card.
        2. Retest unit after making speed sensor adjustment.
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  • I have a problem with a Stairmaster. I will call unit 1. The console will not light up.  I have exchanged console from unit one with a console from another Stairmaster I will call unit 2 it will not lightr up.  But when I install console unit 1 onto unit 2 it will light up and operate correctly.  I have checked and have 13 volts at the plug going into unit 1 console.  The question I have is the lights on the console light up when voltage is applied to console or is something from lower board keeping it from lighting up.  

    If you have any questions understanding what I am asking please contact me at 318 422 2967 or

    Thank you for your assistance



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