bing tracking image
  1. Trailer Lights
  2. Peterson
  3. Tail Lights
  4. Square
  5. Incandescent Light
  6. Red
Peterson Light Kit for Trailers Under 80" Wide - 20' Harness - Driver and Passenger
Peterson

Peterson Light Kit for Trailers Under 80" Wide - 20' Harness - Driver and Passenger

Part Number: M540
In Stock
$50.98
Trailer Lights
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.
By submitting this form, you understand and agree to our Terms of Sale, Website Terms of Use and Privacy Policy.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

In Use/Installed

Customer Photos

4-3/4" x 4-1/2" Square. Incandescent trailer light kit provides all legal lighting and reflectors for trailers under 80". Includes combination tail lights and side markers. Stud mount with included hardware. 20' Harness. PC rated. Great Prices for the best trailer lights from Peterson. Peterson Light Kit for Trailers Under 80" Wide - 20' Harness - Driver and Passenger part number M540 can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
  • All Info
  • Reviews (85)
  • Q & A (0)
  • Photos

Peterson Trailer Lights - M540

Highlights

  • All-in-One Lighting Kit: Provides stop, tail, turn, side marker, and reflex functions for full rear visibility.
  • Ready to Install: Includes 20' wiring harness, mounting studs, hardware, and license plate bracket for complete setup.
  • Stay Legal on the Road: DOT compliant and PC rated for required trailer lighting coverage.
  • Easy Maintenance: Uses replaceable 1157, 168, and 194 incandescent bulbs for simple upkeep.
  • Compact Fit: Tail lights measure 4-3/4" Lx4-1/2" Tx2-13/16" D with 2" stud spacing for standard mounts.
  • Durable Surface Mount Design: Secure stud mount keeps lights stable for consistent performance.
Made in USA

Features to know about

All-in-One Lighting Made Simple: Complete Legal Coverage for Trailers Under 80"

Getting your trailer road-ready shouldn’t take a pile of separate parts. This Peterson kit includes everything needed to stay compliant—two 4-3/4" x 4-1/2" square combination tail lights that handle stop, tail, turn, side marker, side reflex, and rear reflex functions, plus two rectangular clearance lights. It’s DOT compliant and PC rated for a wide 180-degree beam pattern, giving full rear and side visibility. The built-in reflex reflector removes the need for separate reflectors, and the license plate bracket with its own light is ready to mount on the driver’s side.

Straightforward Wiring and Mounting: Ready to Bolt On and Plug In

No rewiring headaches here. The lights surface-mount using included studs spaced 2" center-to-center, and the kit comes with a 20' wiring harness for a clean connection from front to back. Each incandescent light uses standard bulb types—1157 and 168 in the tail lights, 194 in the clearance lights—so replacements are quick if ever needed. Power draw stays efficient at 2.2 amps for the tail lights and just 0.25 amps for each clearance light when running on a 12V DC system.

Reliable Visibility in Any Condition: PC-Rated Illumination You Can Count On

When you’re hauling at night or through low-light conditions, these PC-rated lights keep your trailer easy to see from both behind and the sides. Their 180-degree coverage ensures that other drivers spot your signals well before they get close. This setup meets the lighting requirements for trailers under 80" wide without adding extra lamps or reflectors.

Diagram showing the 180-degree light spread pattern of a PC-rated trailer light, illustrating illumination coverage to the front and sides.

Built Tough for Everyday Use: Proven Peterson Design

These are the same dependable square lights trusted as replacements for Wesbar #7504 and Optronics #TL27BK, so you know they’ve been around the block. The sealed housings guard against dust and road grime, while easily replaceable bulbs keep maintenance simple. With quality construction backed by a 1-year limited warranty, this kit offers a straightforward way to restore or upgrade your trailer’s lighting system without any guesswork.

Specs

Tail Lights

  • Dimensions: 4-3/4" long x 4-1/2" tall x 2-13/16" deep
  • Distance between mounting studs (center on center): 2"
  • Power draw at 12V: 2.2 amps
  • Bulb type: 1157 and 168

Technical diagram showing the Peterson M540 trailer light kit dimensions, including measurements of 4-3/4 inches long by 4-1/2 inches tall and 2 inches between mounting studs.

Clearance Lights

  • Dimensions: 2-3/4" long x 2-1/8" tall x 1" deep
  • Power draw at 12V: 0.25 amps
  • Bulb type: 194

Warranty

  • Warranty: 1-Year limited warranty

M540 Peterson Square Combination Trailer Light Kit for Trailers Under 80" Wide - 20' Wire Harness - Incandescent - Stud Mount - Driver and Passenger Side





Customer Satisfaction Score:

Ratings & Reviews

4.7

85 reviews
Review sort icon
4-3/4" x 4-1/2" Square. Incandescent trailer light kit provides all legal lighting and reflectors for trailers under 80". Includes combination tail lights and side markers. Stud mount with included hardware. 20' Harness. PC rated.

by:

License Plate plastic lasted 2 hours.



by:

The kit wasn’t as complete as advertised. Had to purchase more wire locally.



by:

Shipping was quick and the lights worked out great! Very straight forward install.



by:

Actually I added an extra ground wire to each light. Worked great



by:

Quality looks good, price was awesome. will be installing on an 8'x15' trailer to make me road legal



by:

The exact replacement for my trailer lights with everything needed. Highly recommend.



by:

Great wiring kit. Has everything you need to completely wire a new trailer.



by:

Much better than the cheap made in China ones that I have tried before. This set is very good quality, and a robust wire harness, unlike some of the newer Chinese versions I have purchased. I would expect to get about 5-10 years out of this set.



by:

Always good products when shopping e-trailer. This light package was no different. Excellent service excellent product and excellent follow-up to make sure you're happy..

Sure would love if they would send me a hat and a 2X t-shirt to advertise for them lol. Seriously though buy it you won't regret it.



by:

All the items were quickly delivered and in great shape upon arrival. Only complaint is that there were no instructions for installation. That’s fine for people who know what they’re doing but I’m not that guy. A simple set of instructions would be helpful.



by:

The only issue I have with this assembly is the quick connection at the taillights. It was nearly impossible to make the connection hold. Screw tabs would have been better.



by:

Peterson products are good quality Hopefully the bulbs survived the shipping Everything was rattling loosely around with no bubble wrap or Styrofoam peanuts and all the fragile signs on the box were covered up by the various shipping labels. I prefer to support the the independent sellers like etrailer but next time I’ll go with Amazon



by:

The light kit arrived quickly and was very easy to install on my canoe trailer. Quality of everything is excellent and is working well! I also specifically chose this kit because it was Made in USA!



by:

Replaced lights and wiring on 20 year old utility trailer. Easy install, good instructions. Trailer lives outside in all New England weather. Still working great after a year.



by:

Good product. Did not include instructions, but found the wiring diagram on website. Also, would be nice if the 4 pin adapter had a cover, but I used one from another setup I had. I mainly used old wiring in trailer that I was replacing to pull the new wiring on, through the small wiring tunnels. Everything tested well and I was able to use the trailer the same night I finished install.



by:

I was to understand that the wiring sent would fit trailers up to 18 feet and my trailer is 16 feet and the wire sent wasn’t long enough.



by:

Works great for a replacement



by:

It would have helped if an instruction sheet was included. Tested before install while hooked up to my truck. Needed to ground lights to get them to work and an instruction sheet would have eliminated much frustration. Wire connections on the lights also leaves room for improvement.

Sierra K. profile picture

Sierra K.

6/20/2022

Yes, the white wire is for grounding. This kit does not have an instruction sheet but we do have this wiring help article explaining which colors do what:



by:

Everything needed to replace the broken and missing lights on my trailer.

Victoria H. profile picture

Victoria H.

2/19/2025

That's great to hear, Joel! Please feel free to show us a photo and let us know what you think, once you have it all installed.



by:

This is the 2nd Peterson light kit I've ordered. The nice thing is that it's all there for a complete rewiring of the trailer; marker lights, tail lights, wire, hardware, everything. So convenient.



by:

Order arrived as promised. Happy with decision to use etrailer for my lights.



by:

etrailer is awesome. Great customer service, great products. You are a very knowledgeable group and we appreciate your support



by:

Great lighting kit for my vintage Holsclaw motorcycle trailer.

Richard profile picture

Richard

9/20/2025

This light kit made for a very easy installation and work great



by:

First, I must say I've been very satisfied overall with etrailer and continue to be a return customer. The odering process is straightforward and etrailer kept me informed of the shipping status. I did have a minor problem with the light kit. After a quick phone call with etrailer, they were able to remedy the problem in a few minutes. I also find their installation videos and wiring diagrams to be very useful.



by:

There’s no ground for the taillights so now I’ve ordered a kit with both tailights with a ground for each light.

Mike L. profile picture
Etrailer Expert

Mike L.

9/18/2025

The lamps included in the # M540 kit ground via their mounting studs when mounted to the trailer frame (or metal that's connected to the trailer frame) so a separate ground wire isn't necessary. If the lamp isn't mounted to the trailer frame or metal that's attached to the trailer frame, you can build a simple jumper with a length of wire and a ring terminal on either end. Place one ring terminal on the mounting stud so it's sandwiched between the lamp and the trailer, and secure the other end to the trailer frame.


25
25

See what our Experts say about this Peterson Trailer Lights

  • Why Would Trailer Wiring Have the Running Lights Brighter than Stop/Turn
    Hey William, what is going on is that you have the running lights (lower brightness) and the stop/turn (brighter intensity) circuits swapped and that's why your running lights are brighter than the other circuits.
    view full answer...
  • Is Peterson Trailer Light Kit # M540 All that is Needed to Install Light Kit on Trailer
    Hey Brad, yes the Peterson trailer taillight kit part # M540 that you referenced is all that you need to install trailer lighting/wiring on your trailer and is perfectly compatible with the 4-way kit you installed on your vehicle as well.
    view full answer...
  • Complete Replacement Wiring Setup for Lights and Brakes on a Trailer
    Hey Jeff. We have all of those parts, and I have listed them below, but no there is no one and done kit for a 20' farm trailer's brakes and lights. 7-Way Connector and Junction Box - 7-Way Molded Trailer Wire Connector, 6' Long item # H20044 and Trailer Wiring Junction Box item # 38656 Breakaway Kit - Bright Way Trailer Breakaway Kit with Charger, LED Tester, and 5 Ah Battery item # 3802346 Brake Wire - Deka Jacketed 2 Wire, 10 Gauge, Brake Wire - per Foot item # 10-2-1 Butt Connectors...
    view full answer...
  • Will The Peterson M540 Light Kit Fit A Bracket With 2-1/4" of Head Room?
    I measured from the center of the mounting studs to the top of the lights that come with the Peterson Light Kit # M540 and it is 2-1/2". Just to make sure, I also measure the Optronics Under 80" Trailer Light Kit with 25' Wiring Harness # TL5RK the same way, and they measure exactly the same, unfortunately. With that said, I may have another option available, but the lights will be completely different. If you look at the Optronics Trailer Light Kit # TL16RK, which technically is for trailers...
    view full answer...
    Image 1 for Image 2 for Image 3 for
  • Recommended Trailer Wiring for 5x10 Trailer with 4-Way Trailer Connector
    If you have a 4-way trailer connector like # 118418 then I recommend using a wishbone harness to wire your trailer. The 20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground # A20WB is my recommendation for your wiring because it will allow you to run 2 wired to each side. You will run the brown and yellow to the driver's side, and the other brown and green wire to the passenger side. The white wire will get connected to the trailer frame as a ground. The brown wires on each...
    view full answer...
    Image 1 for
  • Recommended Tail Lights and Clearance Lights For 5' x 8' Utility Trailer
    I would be happy to help! For replacement lights I recommend starting with the Peterson Light Kit for Trailers Under 80" Wide - 20' Harness - Driver and Passenger # M540 which includes the two tail lights, and two amber clearance lights. Since you mentioned that you also have red side marker lights on the front I recommend two of the # MC48RB. This will include all of the new wiring and lights needed, but I do recommend using heat shrink butt connectors like the # DW05744-10 to give...
    view full answer...
  • Submersible Version of Peterson Light Kit part # M540
    For a submersible version of the Peterson Light Kit part # M540 that you referenced you'd want the # TL5RK which comes with the exact same style of lights, wiring and bracket but is designed for boat trailer applications like yours! I attached an install video for this for you to check out as well.
    view full answer...
  • Troubleshooting Trailer Wiring Where Bulb Keeps Blowing Out
    Hey Brad, what is most likely going on is that there's a short on the wiring for the circuit that has the bulb that keeps blowing out. Go over that circuits wire looking for any cut/exposed wire and fix as needed. Most likely it's exposed wire touching the trailer frame. If it's not there it is something to do with the trailer wiring connectors either on the tow vehicle or the trailer. Look for issues there and fix as needed and let me know what you find. The bulb replacement would be...
    view full answer...
  • Will Peterson Light Kit #M540 Replace the Lights on my Trailer?
    You would be able to add lights with the Peterson Light Kit for Trailers # M540 and since they have a new 4 way connection it should solve any issue you're having; that being said, I can run you through some quick steps to troubleshoot the lights on the trailer and avoid having to buy a new set of lights. It sounds like there may be an issue with the wiring harness on the vehicle or the trailer wiring that is keeping these lights from functioning, so I'll give you a couple of troubleshooting...
    view full answer...
  • Parts Needed to Add Separate License Plate Bracket and Light With Peterson Light Kit M540
    You can tap into the running lights(brown wire) on the Peterson Light Kit # M540 with a Tap # SWC502905-1. That will allow you to run 16 Gauge Wire # 16-1-1 to a Optronics LED Trailer License Plate Light # OPT97FR. You will be able to ground the negative wire to the steel frame, as your light kit uses the frame for the ground circuits.
    view full answer...
  • Can LED Trailer Tail Lights be Used With Original Wiring on Older Boat Trailer
    You can use the Peterson Light Kit # V944 on your boat trailer from 1982 with its original wiring. Just make sure that the wires are in good shape and not stripped or otherwise damaged/exposed and these LEDs will work.
    view full answer...
  • Availability of Replacement Tail Lights for Peterson Boat Trailer?
    The lights I recommend for you are the Peterson # M540. These are epoxy-sealed submersible lights which will stop water from interfering with the bulbs. Keep in mind this does not protect the wiring, so you may want to take a look at some liquid electrical tape, # SWC50122. I also recommend you use heat shrink such as # DW05450 for all your wiring, which will help protect it.
    view full answer...


Info for this part was:

Employee Jameson C
Expert Research:
Jameson C
Employee Joshua S
Video by:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Kathleen M
Installed by:
Kathleen M
Employee Ryan G
Installed by:
Ryan G
Employee Daron K
Edited by:
Daron K
Employee Brian T
Written by:
Brian T

At etrailer we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time.