How to Test Your Sensor/s (Potentiometer)

How to Test Your Sensor/s (Potentiometer)

Project Description

How to test your sensors

So you have done everything and still not getting any joy from your selespeed. Have you tested your sensors? Most of the time the answer to this is NO.

Well testing them is very simple you will need the following tools:

  • a Multimeter (to measure ohms)
  • Flat Screwdriver (medium size)
  • Extra set of hands (optional)


Remove your sensor (do not mix them so remove them one by one) , place your multimeter on a 2k or higher reading and measure over points A and B. You should get a reading of 1200 ohms but this varies due to temperature and you have a 2-4% tolerance so it means a reading between 1150 – 1250 ohms is the right reading. Any reading outside of that will give your selespeed some funny side affects ranging from gears scratching during gear change to funny clutch behavior.

Lets assume that the reading is in tolerance you can test the track consistency (for dead spots) by placing the probes over point A and C and turning the sensor inside with the flat screw driver to check that the ohm reading is nice and constant. Thats it folks if your sensor pass these steps then you no they are fine.

Actuators position sensor


Image to show sensor points

The sensors that send the position of the gear selection, gear engagement and clutch control actuators to the
Selespeed control unit are single ramp potentiometers installed directly on the electro-hydraulic group. They are
powered with 5V+/-0.5V by the control unit CFC 208F. Maximum resistance between pins A-B is 1200 +/-
50 Ohm at 20°C.