Vehicle example: PTO on Freightliner M2

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Step 1: Freightliner PTO switch

  • PTO Switch is located center of the dash under the radio.
    • Switch does not switch polarity like a normal switch.
    • Can not acquire PTO signal here.
    • Switch controls a chassis module to turn PTO on and off.

Step 2: Locating transmission interface plug


  • The transmission interface plug is grey and is located in one of 3 places.
    • Under hood near firewall on drivers side.
    • On frame rail just past drivers rear of cab.
    • End of drivers side frame
  • Vehicle options dictate where harness is and what the harness pin out is. See documentation above for details.

Step 3:  Transmission interface harness

  • This picture shows what the transmission interface harness looks like when found under the hood.
  • It was wrapped in green tape to the red loomed harness.
  • It was between the steering shaft and fuse box.

Step 4: Test for PTO wire


  • There are several PTO systems available. Please refer to the attached docs (above) for electrical details.
  • Installer should test for PTO at the transmission interface plug using a DMM only! NO TEST LIGHTS!

Step 5: Relay

  • Use a relay to send (-) ground signal to our device when PTO is on.
  • See hardware specific page for general diagram.

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