Troubleshooting No Resistance on Stairmaster Stepper 4400CL and 4600CL


Here we cover troubleshooting no resistance on the Stairmaster 4400CL and 4600CL Stepper.

A common misconception about battery-powered units, it that it only requires you to step on the pedals to power the console; when in fact 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 as well as the battery.

Tools Needed:

  • Voltmeter
  • 7/16" Wrench
  • An assistant for testing purposes


  1. Test the battery voltage. Set your voltmeter to read DC voltage (if your meter has ranges, use a range appropriate for the 6-volt battery being tested).
    1. Place your voltmeter leads to the battery terminals and have your 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.
    4. A good speed sensor will produce about 3 VAC before the console powers up.
  3. 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.
    2. The proper gap of the speed sensor to the disc is about the thickness of a business card.
    3. Retest unit after making speed sensor adjustment.
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