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Optronics LED Trailer Tail Light - Stop, Turn, Tail - Submersible - 10 Diode - Oval - Red Lens

Optronics LED Trailer Tail Light - Stop, Turn, Tail - Submersible - 10 Diode - Oval - Red Lens

Item # STL78RB
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Trailer Lights STL78RB - Submersible Lights - Optronics
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7-9/16" x 3-5/16" Oval. 3-Function, waterproof LED light acts as brake, tail, and turn signal. Durable polycarbonate housing and lens. Surface mount with built-in flange - hardware not included. 3-Wire design. Great Prices for the best trailer lights from Optronics. Optronics LED Trailer Tail Light - Stop, Turn, Tail - Submersible - 10 Diode - Oval - Red Lens part number STL78RB can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (653)
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Optronics Trailer Lights - STL78RB

  • Tail Lights
  • Oval
  • LED Light
  • Red
  • 6-1/2L x 2W Inch
  • Surface Mount
  • Stop/Turn/Tail
  • Submersible Lights
  • Optronics

7-9/16" x 3-5/16" Oval. 3-Function, waterproof LED light acts as brake, tail, and turn signal. Durable polycarbonate housing and lens. Surface mount with built-in flange - hardware not included. 3-Wire design.


  • Red, oblong light functions as stop, turn, and tail light
  • Sealed, waterproof housing and lens unit
  • Corrosion resistant
  • 10 Super LEDs (Light Emitting Diode)
  • Flange mounts with four mounting holes in the center of each side
  • Wiring design contains lead wires and a ground wire to mount to all surfaces
  • Wire functions:
    • Red: Turn signal and brake
    • Black: Tail light
    • White: Ground


  • Overall dimensions: 7-9/16" long x 3-5/16" tall x 3/4" thick
  • Distance between mounting holes (center to center): 7" long x 2-3/4" tall
  • Diodes: 10
  • Power draw at 12.8V:
    • Stop/turn: 0.243 amps
    • Tail: 0.046 amps
  • Lifetime warranty on LEDs

Optronics STL78 Series Combination Trailer Tail Light 6 Inch Oval Sealed LED Light Surface Mount Diagram

Sonically Sealed, Waterproof Trailer Light

The waterproof construction of this light makes it ideal for use on trailers that may be submerged, like a boat trailer. The housing and lens are sonically sealed together to create a single unit, which means that water will not get into the light and damage the diodes or circuit board.

Surface-Mount Light

Surface mount light

Surface-mount lights install flat against the surface of the trailer, so a hole does not need to be cut into the trailer for the light. This type of light is installed using a flange or bracket that has mounting holes. And mounting hardware is used to secure the light to the trailer.

STL78RB Sealed, 6-1/2" Oval LED Trailer Stop, Turn and Tail Light, Flange Mount, 10 Super Diode 0.243V/0.046A

Alternate part number: STL-78RB

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Optronics LED Trailer Tail Light - Stop, Turn, Tail - Submersible - 10 Diode - Oval - Red Lens - STL78RB

Average Customer Rating:  4.8 out of 5 stars   (653 Customer Reviews)

7-9/16" x 3-5/16" Oval. 3-Function, waterproof LED light acts as brake, tail, and turn signal. Durable polycarbonate housing and lens. Surface mount with built-in flange - hardware not included. 3-Wire design.


After figuring out what wires were what on my trailer and the lights everything works as it should.



After a year everything is still working as it should.


Very nice product. Installation on my very old utility trailer was easy. I like the slim design compared with my old chunky incandescent lights which were easy to break and not as bright as these LEDs.


Was exactly what I needed: Surface mount, holes exactly 7 inches apart for the sides. Needed it for a replacement on our 2018 Grand Design 399TH Momentum.


The 10-diode tail lights were well made, bright, and easy to install. We also ordered and installed the matching reflector rings, which were also easy to install, look great, and give added safety features.



Lights are sleek and a perfect replacement. Still doing an excellent jodb! Would purchase again if needed.


Super easy to install. Took me about 30 minutes to do both lights. Good & bright. Much better than the factory installed tail lights. Very pleased!


After one of the the incandescent trilights the factory installed on my trailer burnt out I discovered they where sealed and the bulbs could not be replaced,
So I purchased two of these and discovered they are ery nice lights and unlike incandescent lights they don't screw up the turn signal flash rate.

I am now in the process of rebuilding a trailer mounted generator and just ordered 2 more of them for that trailer and I also bought LED marker lights from the same manufacturer.

If you need new or replacement taillights or marker lights LED's are the way to go, long lasting, nice and bright and in my opinion they way they instantly light up get more attention from drivers behind me possibly reducing the chances of getting my trailer rear ended by a inattentive driver.


Now that I'm finishing up on my Teardrop Trailer I've got these lights installed, along with a LED tag holder, and LED marker lights. I had also bought the fenders from etrailer they look great, and I get a lot of comments how good all these parts look. Oh and the prices are better then any place I could find.......Thanks etrailer


After one year, the Optronics LED Trailer Lights are still working as expected with zero issues!

These were bought to replace the original LED lights which had failed. The Optronics LED Trailer lights were a direct match to the originals and installation was simple.

Overall, very satisfied with the product and would purchase again!


I bought one of theses lights last year to replace one that had some of the LED's going out. Same manufacturer and same part number. The new light uses a different type of LED (square LED). The old style used an LED that looks more like a small bulb. I have 4 of these on the back of my 5th wheel trailer. The other three started going bad so I just replaced them as well. I have other LED lights inside the trailer that use the same type of LED as the new tail lights. I've had those lights for 6 years with no problems. . I suspect these new lights will last much longer with the new type of LED.


These are worth the price, look good and are very bright. I've had a few of the center LEDs go out but 10/10 would order again.


Easy install looks great on my trailer without needing to cut the oblong holes for the light. Only need to drill a small hole for the wires and the mounting screws.


Good product. Horizontal bolt hole spacing is the same as a license plate so it conveniently mounts anywhere a license plate would. The LEDs are bright enough as auxiliary running/turn/brake lights and the wiring is simple. The mounting flange is not very strong plastic so you have to be careful not to crank down on the mounting bolts. There is no hardware included and no gasket for the backside, which is a bummer. Otherwise, a very nice product.


Wired them in and they light up, blink, and do everything else they're supposed to do. Let me also mention that they are BRIGHT at night. Loading the boat onto the trailer at dusk/after dark they're almost blinding when the pickup driver steps on the brakes. Lol


Fast delivery and packaged with care. Thank you! Will definitely be ordering again.


the light will work for my intended use but it would have been nice to get a wiring diagram for the red, black, and white. to tell a customer witch was hot ,ground and turn signals


I had a hitch carrier in the garage and wanted to add brake lights/turn signals. Since there were no mounting locations for lights, I needed a surface mount option. These fit the bill. They work great and were easy to wire with the harness I bought.


Works grear


Good product and fast shipping


Quality product well made and designed,
priced. Best suited for my application. Also purchased the red reflector snap ring that covers the mounting flange and screws.


Really good service.


The order was received and delivered in a timely fashion. It could not have been any easier. I will use etrailer again and recommend them for RV parts and more.


I have a hard time finding this model in Canada and these are a great deal!



Light is working well after one year of use!


I just got the product so I do not know how it WORKS. But it is on my trailer and it fits well. It looks great. And I have full anticipation that it will be wonderful.

I will say this, your service and delivery are very good. I have received all products on time or even a bit early. And customerservice has been very responsive.


Customer loves the new optronics light and fits perfectly without any modifications


Nice products, good prices. Wsa shipped right out, but took forever it seemed to get here. Very well packaged. I am building a 1/2 scale teardrop trailer to pull behind my motorcycle. Just getting started.

Show More Reviews

See what our Experts say about this Optronics Trailer Lights

  • LED Tail Light # STL78RB Recommendation for a Coleman Popup Camper
    It sounds like the LEDs that you previously had installed on your trailer were single function LED lights, and that is why if they saw any power they were lit regardless if different blinker, tail light functions were being applied at the same time. These Optronics Trailer Lights, part # STL78RB, that you referenced are designed for all of the different stop, turn, and tail light functions and should work very well for you.
    view full answer...
  • Trailer Left Side Running Lights Not Working All Other Lights Work
    On many trailers the running light wires are jumped from one side to the other on the trailer. This is because there is a single running light wire only ran on one side. A wire would have to be spliced in on the one side, ran to the other side of the trailer, and connected to the running lights. If using a junction box, the one running light wire from the trailer connector can go to a single terminal and from there you can run separate wires for the running lights on each side of the trailer....
    view full answer...
  • Are Load Resistors Required When Installing LED Lights on a Trailer
    You will not need to add any diodes or other modules to prevent hyperflashing or any other bizarre taillight behavior when you install this Optronics Tail Light # STL78RB on your trailer. If you were installing LED tail lights on a vehicle and replacing the lights on the turn signal circuit then you would need a load resistor so that the blinkers would function correctly.
    view full answer...
  • Right Turn Signal Does Not Work When Tailights Are Active
    I suspect you have a ground problem as that is the main cause of most lightning problems but there could also be a blown fuse or shorted out wire so you will need to work your way through the steps below. I would first check the trailer towing fuses on the vehicle to make sure none are blown. Once this is done I would then move onto checking the grounds. When I say check grounds, I do not mean merely looking at them but rather remove the bolt/screw, sanding down the surface and then re-attaching....
    view full answer...
  • How Does the Optronics Trailer Lights # STL78RB Wire to the Passenger Side of a Trailer
    On the right side of your trailer the green wire should be the right turn/stop signal and the brown should be the running or taillights. So basically the brown of your trailer should run to the black of the light, the green of your trailer should run to the stop/turn signal, and the white should run to the white. If that is how you wired it up on your trailer and you are still having problems when the headlights are on that would indicate you have a ground issue. What you will want to...
    view full answer...
  • 4-Pole Trailer Wiring Functions & Wiring Installation for Optronics Oval LED Trailer Light STL78RB
    In standard 4-pole trailer wiring there are actually three active lighting circuits plus a ground. The tail light (or running light) function is carried on the (usually brown) wire that is next to the ground pin. Please refer to the linked photo of a trailer-side 4-pole connector that shows these circuit/function assignments. The next pin over, the one for the yellow wire, typically carries the LEFT stop and turn light functions which are combined onto this one wire; and the RIGHT stop...
    view full answer...
    Image 1 for
  • Recommended Trailer LED Tail Lights for Trailer Ramp
    Because they are side marker lights, they are not designed for the dual brightness function of tail an brake lights. You can wire them to be tail lights or brake lights only, but you may be overloading their circuit with the brake light signal strength. I recommend you use the Sealed, 6-1/2" Oval LED Trailer Stop, Turn and Tail Light # STL78RB to give you the features you are seeking. The Red wire will be your stop light, the black wire will be your running light and the white wire will...
    view full answer...
  • Can LED Brake and Turn Signal Lights Replace Incandescent Lights on an Old Trailer
    Yes, you can use LED light in place of incandescent lights for brake and turn indicators on your trailer however, you will want to replace them all for continuity sake. Although both LED and incandescent lights work off of 12 volts, the incandescent lights pull more amperage and may burn the LED lights out prematurely if you mix LED and incandescent lights. I have attached a brief video review of the Optronics Oval LED Light # STL78RB that you referenced.
    view full answer...
  • Troubleshooting Trailer Running Light Circuit Not Functioning on One Side of Trailer
    Since your running light issue is only on one side of the trailer that indicates that the issue is on the trailer wiring. Most likely you have an insufficient ground on the light assemblies on that side of the trailer. If you can fix/improve the ground on that side of the trailer you will fix the issue you are having. A lot of trailer lighting assemblies ground through the mounting hardware of the light so make sure your lights are mounted to a clean metal surface. You can also run jumper...
    view full answer...
  • Troubleshooting Malfunctioning Trailer Lamps on 2015 Lakota Horse trailer
    It sounds as if you might have two issues going on. When the turn signals are activated, all the diodes in the LED lamp should blink. If they don't (assuming that particular lamp was wired correctly), the lamp is faulty and should be replaced. For the issue with the turn signals not functioning when the running lights are switched on, that sounds like a ground issue. When you turn on the vehicle headlights, the trailer wiring system is drawing maximum amperage. If there's a ground problem,...
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  • Availability of Multifunction LED Trailer Taillights for Use on a Motorcycle
    The MCL19RB and MCL19CRB are clearance light so they have only one function. For more than one function, stop, turn, brake, you will need to look at taillights. I have included a link to the oval, LED taillights below. One that is very similar to the lights you referenced is the Sealed, 6-1/2 inch Oval LED Trailer Stop, Turn and Tail Light, Flange Mount, 10 Super Diode, # STL78RB.
    view full answer...
  • Optronics Oval LED Light Recommendation to Replace an Older Style Optronics Light
    I do have a solution that should work for you, but we do not carry any Optronics lights with the style connector you have. You could get a Optronics Trailer Light # STL78RB that you referenced, and to install it you would just want to cut of the connector that is on your trailer and then wire the the three wires to the wires of the # STL78RB. The white wire of the # STL78RB will run to the ground wire of your trailer wiring, the red will run to the turn signal/brake wire and the black...
    view full answer...
    Image 1 for
  • Trailer Turn Signal Not Working with Running Lights on a 1993 Palomino Pop-Up Camper Trailer
    On trailers, the brake light and turn signals are on the same circuit and use the same bulb or LEDs. When you are braking and have the turn signal on, the turn signal should override the brake light on that side. The running lights should be independent of all of this. It sounds like there is a bad ground somewhere. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light. Make...
    view full answer...
  • Can the Optronics Trailer Tail Light # STL78RB be Mounted Vertically and Horizontally
    Trailer tail light # STL78RB is symmetrical on the horizontal and vertical planes so you can position the light as needed for the best fit for your application. I have included a link to a video review of this light for you.
    view full answer...
  • Is the Optronics LED Trailer Stop, Turn and Tail Light Assembly # ATL78RB Sold Individually
    The Optronics LED Stop, Turn and Taillight you referenced # STL78RB is sold individually. If you need two of them, be sure to state that you need a quantity of 2.
    view full answer...
  • Troubleshooting Right Turn Signal Circuit Always Active on Vehicles Trailer Wiring
    If I am understanding you correctly it sounds like you have 12 volts on the right turn signal at all times. And that you even tested the wiring of your truck further and further up the vehicle's wiring and still there was voltage on the circuit. This to me sounds like a bad relay. A bad fuse would cause the circuit to stop functioning all together, but a bad relay will potentially cause a circuit to be active at the wrong time. Check under the hood of your 2003 Silverado looking for...
    view full answer...
  • Is the Optronics Light part # STL78RB Sold Individually or Separately
    The Sealed, 6-1/2" Oval LED Trailer Stop, Turn and Tail Light # STL78RB that you referenced is sold individually.
    view full answer...
  • Troubleshooting Trailer Wiring that When Connected Causes Issues on Vehicle Wiring
    Sounds like the trailer wiring has some issues. Most likely a short or grounding problems. I know that's not very specific but your best option is to start at the trailer connectors and make sure they are clean and free of corrosion and then work your way back on the wiring of the trailer fixing any exposed wire as needed. Also make sure the grounds of the lights are solid as well. I attached a help article on trailer wiring troubleshooting as well.
    view full answer...
  • Trailer Brake Lights Not Working on Trailer with Running and Brake Lights on Same Circuit
    Usually on a trailer the turn signals and brake lights are on the same circuit and not the running lights and brake lights. On a light such as # STL78RB the red wire is for turn signal and brake lights but on your set up you would have to use it for the running and brake lights. The black, which is normally running lights, would have to be the turn signal circuit.
    view full answer...
  • Trailer Tail Light Turn Signal Does Not Work but Brake Light Does
    The turn signal and brake lights are on the same circuit. If one is not working then it is likely because there is a bad or weak ground connection that will need to be addressed. Make sure that the vehicle and trailer side connectors are clean and free of corrosion inside and out. Next make sure the main trailer connector ground and the grounds for all of the lights are attached to clean and corrosion free bare metal surfaces. If the trailer has an aluminum frame, tilt bed, or folding...
    view full answer...
  • Tips for Picking Out Install Hardware for Optronics LED Flange Mount Trailer Taillight # STL78RB
    The holes of the Optronics LED Trailer Tail Light # STL78RB are right at 1/4 inch in diameter so going with a install bolts that are near 7/16 of an inch will be ideal. I'd recommend taking the light to a hardware store when picking out the hardware you plan to use so that you can make sure the head of the bolt also fits the recessed area of the flange and that you have the length you'd need with the bolt ran through the flange as well. I attached an install video for this light for you...
    view full answer...
  • Locating Replacement Tail Lights for 2003 Karavan Boat Trailer
    We have a large selection of trailer tail lights available. In order to choose the correct replacements for your 2003 Karavan Boat Trailer, I recommend taking a few measurements on your existing unit. You can also look for a model number or manufacturer on the assembly itself to see if we might have an exact replacement part. If you are able to locate the model number on the tail light assembly, I will be happy find a compatible replacement. A sealed light like the Optronics # STL78RB...
    view full answer...
  • Troubleshooting Trailer Running Light Circuit Not Working on Left Side Fender
    Most likely a bad ground for the light assembly on that fender. Since it's an aluminum trailer make sure the ground wire of the light is ran back to the main ground wire of the trailer and you should see it start to work again.
    view full answer...
  • Left Trailer Brake Light Does Not Work But All Other Lights Do
    It is strange any time a turn signal works but the brake light on the same side doesn't. this is because the brake and turn signal lights are on the same wire/bulb. The usual culprit is a bad ground. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light. Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The...
    view full answer...

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