Commercial Vehicle - Transponder Support and Questions

1.  What is a transponder? A transponder is a small electronic device that attaches to the inside of the vehicle’s windshield and allows trucks to bypass weigh stations by electronically verifying the legal weight, safety rating and credentials of the truck as it continues down the road at freeway speeds.

2.  How do I apply for a transponder?
Complete a Transponder Application (pdf 128kb) and mail it with a check and a copy of the vehicle registration/cab card to the address provided.

3.  How much does a transponder Cost?
Washington charges a one-time fee of $35 per transponder.

4.  How long does a transponder work?
Transponders have an average battery life of five years.

5.  Can I transfer a transponder to another vehicle?
Yes. Complete the Transponder Updates/Transfer (pdf 25kb) form and fax it with a copy of the Vehicle Registration to the number provided on the form. 

6.  Where can I find my transponder number?
The transponder number is located near the barcode and written in two different formats. The eight digit (hexadecimal) number beginning with a 2 and a nine digit (decimal) number beginning with a 5 or 6. Washington can process requests using either format.

  • 20xxxxxx or (xxx)54xxxxxxx
  • 24xxxxxx or (xxx)60xxxxxxx
  • 28xxxxxx or 67xxxxxxx

7.  What is Washington’s Bypass Criteria?

  • The vehicle registration must be current
  • The vehicle must be assigned a USDOT number.
  • The carrier must have a safety score of 74 or below.
  • All necessary taxes and registrations must be paid and current.

8.  What if my transponder indicates a green light but the roadside sign says report?
If the transponder light does not match the roadside sign follow the In-Cab Signal. 

9.  Do I return my transponder if it’s no longer needed?
No. Once a transponder has been purchased it is your property.

10.  In addition to the Bypass Criteria what are the requirements for receiving a Green Light?
Both the vehicle and the load must have a legal height and weight.

11.  Can I replace the battery in a transponder?
No. Removing the battery destroys the transponders memory.

12.  Can I register my Transponder in other states?
Yes. Once a Transponder is purchased it is your property and can be registered for use in any NORPASS or PrePass jurisdiction as well as the Oregon Green Light system. Transponders registered with PrePass will be subject to PrePass regulations and fees.

13.  Can I carry more than one Transponder in my truck?
It is not recommended. Having multiple transponders in a vehicle can prevent the correct one from being read.

14.  Will my PrePass Transponder work in Washington?
Yes, Washington can register PrePass Transponders; however, the carrier must first contact PrePass. Washington will only register a PrePass transponder upon receipt of a Letter of Authorization from PrePass.

15.  Where do I place my Transponder at on the windshield?

  • Near the center of the windshield
  • On the passenger side of a divided windshield
  • Either three inches from the top or just above the dash board

16.  How much time will I save using a Transponder?
On average bypassing a weigh station saves 3-5 minutes.

17.  How many Washington Weigh Stations use Transponders?
Transponders can be used at eleven weigh stations in Washington.

18.  What are Red Lights sent for?

  • Overweight, over axle weight or over-height vehicles
  • The carrier has a safety score of 75 or above
  • The vehicle registration is not in current
  • There is a normal 5% random pull in rate
  • Special emphasis, federal government inspections or other mandated inspections

19.  How can I prevent unnecessary Red Lights?

  • Center the Vehicle in the Weigh In Motion (WIM) lane
  • Maintain a steady highway speed of around 50 to 55 miles per hour
  • Provide at least a three second gap between your truck and other 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 vehicle
  • CB’s may cause an interruption of the signal to the transponder

20.  What should I avoid doing when approaching a Weigh Station?

  • Excessive speed
  • Change of speed
  • Following too close to another vehicle
  • Lane changes
  • Excessive braking prior to reaching the Weigh-In-Motion scale

21.  Who do I call if I have problems?
Contact the Washington State Department of Transportation Transponder Administration at 1-888-877-8567.

22.  How does the Automated License Plate Recognition (ALPR) work in Washington?
Commercial vehicles are electronically screened on the mainline approximately ½ mile ahead of the weigh station. An ALPR camera reads the license plates and uses this to identify a vehicle record in the database. Vehicles that are of legal weight, have valid /current credentials, and a good safety rating are signaled to bypass the weigh station via changeable message signs. Vehicles that need further scrutiny are signaled to report to the weight station via changeable message signs.