Transponder Support and Questions

Transponders are used to identify commercial vehicles so the legal weight, safety rating, and registration information can be verified as the commercial vehicle approaches the weigh station.  This allows safe and legal carriers to continue driving so officers can focus on high risk carriers.

Electronic Screening at Weigh Stations

  • 11 Washington Weigh Stations have electronic screening technology that check commercial vehicles for violations while in motion (view map)
  • If a violation is found the commercial vehicle receives a red light and is directed to stop at the weigh station

Purchase a Transponder

Mail in a Transponder Application (pdf 128kb) with:

  • A check or money order for $35 each
  • A copy of the commercial vehicle registration/cab card
  • We do not accept credit cards for transponder sales

Register a Transponder (WA, ID, SD, NY, & CT)

Email ( or Fax (360-705-6836):

  • A copy or picture of the commercial vehicle’s registration/cab card
  • The USDOT Number
  • The transponder number or a picture of the transponder with the barcode numbers
  • We do not make transponder updates over the phone

Registering Transponders in Other Systems

Provide the transponder number and commercial vehicle information

Registering PrePass Transponders in Washington

Requests to register a PrePass transponder must come directly from PrePass

Multiple Transponders

  • Having multiple transponders in a commercial vehicle is not recommended
  • A single transponder should be registered for all electronic screening systems

Transponder Number

The transponder number is located on the device near the barcode

  • 20xxxxxx or (xxx)54xxxxxxx
  • 24xxxxxx or (xxx)60xxxxxxx (typically gray)
  • 28xxxxxx or 67xxxxxxx (typically black)
  • 2Exxxxxx or 77xxxxxxx (typically white)

Transponder Location

  • Near the center of the windshield
  • On the passenger side of a divided windshield
  • Either three to six inches from the top or just above the dash board
  • Try to keep it a couple inches away from any metal

Bypass Requirements

  • Current commercial vehicle registration
  • USDOT Number of the Carrier Responsible for Safety
  • Carrier safety score of 74 or below
  • All required taxes and fees must be paid
  • Commercial vehicle and load must have a legal height and weight

Common Red Light Reasons

  • Overweight, over axle weight, or over-height
  • Carrier safety score of 75 or above
  • Expired commercial vehicle registration
  • The transponder is not registered correctly (still assigned to an old VIN)
  • Random pull in rate set by officers at the weigh station
  • Special emphasis, federal government inspections, or other mandated inspections

Preventing Red Lights

  • Center the commercial vehicle in the Weigh-In-Motion (WIM) lane
  • Maintain a steady highway speed of around 55 miles per hour
  • Provide at least a three second gap between vehicles
  • Secure tarps so the wind does not trip the over-height detector
  • Avoid dark metallic window tinting that can interrupt the transponder signal
  • Avoid metallic windshield visors that can interrupt the transponder signal
  • Use only one transponder in your commercial vehicle
  • CB’s may cause an interruption of the signal to the transponder

Follow In Cab Signal

  • If the transponder light does not match the roadside sign follow the In-Cab Signal


  • 3-5 year average battery life
  • Not designed with replaceable batteries

Returning Transponders

  • Once a transponder has been purchased it is your property
  • We do not want it back
  • To unregister before disposing, email or fax the transponder number with a request to delete/cancel to the contact information below

Contact Us