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Optronics LED Trailer Parking Light with Turn Function - Submersible - 10 Diodes - Oval - Amber Lens

Optronics LED Trailer Parking Light with Turn Function - Submersible - 10 Diodes - Oval - Amber Lens

Item # STL78AB
Our Price: $23.22
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Shipping Weight: 0.28 lbs
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7-9/16" x 3-5/16" Oval. Waterproof LED trailer light serves as a parking light with turn signal function. Durable polycarbonate lens and housing. Surface mount with built-in flange. 3-wire pigtail. Great Prices for the best trailer lights from Optronics. Optronics LED Trailer Parking Light with Turn Function - Submersible - 10 Diodes - Oval - Amber Lens part number STL78AB can be ordered online at or call 1-800-940-8924 for expert service.
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Optronics Trailer Lights - STL78AB

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

7-9/16" x 3-5/16" Oval. Waterproof LED trailer light serves as a parking light with turn signal function. Durable polycarbonate lens and housing. Surface mount with built-in flange. 3-wire pigtail.


  • Oval LED trailer light serves as a parking light with turn signal function
  • Sonically sealed, waterproof housing and lens unit is submersible
  • LEDs make great replacements for incandescent lights
    • Last 50 times longer
    • More efficient - provide brighter light with less power output
    • No bulbs to replace - no brittle filaments
  • Durable polycarbonate lens and housing
  • Amber lens over white LEDs
  • Surface mount with built-in flange - hardware not included
    • Light can be mounted in any 360-degree position
  • 3-Wire design hardwires to trailer
  • DOT compliant


  • Dimensions: 7-9/16" wide x 3-5/16" tall x 3/4" deep
  • Distance between mounting holes (center on center):
    • Horiztonal: 7"
    • Vertical: 2-3/4"
  • Diodes: 10
  • Power draw at 12.8 V:
    • Turn: 0.243 amps
    • Parking light: 0.046 amps
  • Lifetime warranty on LEDs

Optronics STL78 Series Parking Light with Turn Function 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.

STL78AB Optronics LED Trailer Parking Light with Turn Function - Submersible - 10 Diodes - Oval - Amber Lens

Alternate part number: STL-78AB

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Optronics LED Trailer Parking Light with Turn Function - Submersible - 10 Diodes - Oval - Amber Lens - STL78AB

Average Customer Rating:  4.8 out of 5 stars   (55 Customer Reviews)

7-9/16" x 3-5/16" Oval. Waterproof LED trailer light serves as a parking light with turn signal function. Durable polycarbonate lens and housing. Surface mount with built-in flange. 3-wire pigtail.


I mounted these behind a plate to replace the cloudy front lights on my truck. Much better look. They were a little lighter weight than I expected but the build quality looks good.


nice flat mount lights bright


Worked great as a replacement for OEM that was no longer available for RV. I also replaced the back side marker lights so the front and back matched.
Pat C did a great job in completing my order with substitution for out of stock resistor.


STL78ab 6-1/2" Oval LED Trailer Turn Signal and Parking Light, Flange Mount, 10 Super Diode: Nothing wrong with this light, but now that I purchased the Miro-Flex Technology with the new generation of LED, its hard to have these as my favorites anymore. I did purchase the Reflective ring to put around it, and I like that product, it adds to this light and coves up the black frame with a highly reflective amber reflective area.


E trailer is a fantastic place to shop. The selection and price and even more important I like to call my orders in , their reps who I talked to were all knowledgeable, very helpful and customer friendly.

I even added to my order a day later and they went the extra mile to ensure everything went out in one package.

These are great lights we want to be sure they had turn signals as when towing it gives us the confidence to know everything is working well.
We needed submersible and LED and wanted to be sure they fit the trailer and would work no matter the surface material, and were easy to install.
I wish I had known of e trailer years ago, I am a customer for life.


Replacement for old marker lights that had been discontinued on my class a rv, they look nice are bright and an improvement.



All the products are performing great...........very happy


Quality product. Well built and seem to be quite durable compared to the old single bulb style. I installed these on the sides of my trailer for added visibility at night and also on the back of my van to aid the factory hazard flashing lights.


These lights were to replace the ones not working on my boat trailer. You would think that the skeeter dealership could either have them in stock or be able to order. Thank you for being there etrailer.


Originally purchased this exact part from a large auto parts store for $100 and they needed 2-4 weeks to process this "special order part". I cancelled that order as soon as I found it here for 1/5 of the cost and It arrived really fast, an easy buying process, and the follow up customer service was great. We are installing this part next month. If anything happens to go wrong with the light, I have a lot of faith that CS will be nothing short of amazing in helping us resolve the problem.


My lights came in before scheduled, as usual, and were in perfect condition. No defects. I bought two of them, along with a set of the red versions to put on my headache rack. They are very bright, much brighter than my incandescent stock tail lights. The only thing I don't like is how you can see the circuit board in them, but that's only up real close.


These lights are perfect for updating my side marker/turn signal lights. Their slim profile and unique lighting sequence added a sleek and stylish appearance to my RV.


Very bright, great quality. Fit my 5th wheel travel trailer perfectly.


My new light.


Very nice light. Wouldn't mind if there were amber reflector ovals to go around this, similar to the red reflector ovals.


This light is well made, but was a little disappointed because the
"stop-turn" connection only lights the center 4 LEDs brightly. I
was expecting that all 10 would be brightly lit for better visibility
on this setting.


I have used Etrailer twice to buy lights for custom bumpers, and the service has been excellent. The shipping is super fast and the lights are the highest quality. I will not be using anyone else.


Great light at a good price but have had several that the wires broke off flush with the housing.


Like the look very slimline. Makes my 2010 car dolly look like a newer version


Nice bright lights , I used these and 2 more ( red, for the brake; and and white for the backup) on the back of a 1980 service body truck to replace the ugly ones that came on the truck


I have order bifore from Etrailer corp. And is a real good product they have. That's why I re order some stuff for my business again. And as soon as I need more stuff I will reorder again,


Excellent product. Used them as part of a total rewire and re-light of 48' conestoga trailer.


Beat price around and fast shipping!


perfect and bright ... fast delivey ... sale well done



All are working, just as bright now as when new, do a GREAT job protecting the backside of camper


super bright


Easy to install. Works and looks great. A lot better than my old incandescent lights.

Show More Reviews

See what our Experts say about this Optronics Trailer Lights

  • Recommended LED Trailer Light Under 3.25 Inches Tall
    The lights we offer that are closest to the size you mentioned that we carry is part # STL78RB. These lights measure 7-9/16 long when you also include the mounting flange, x 3-5/16 inches wide, x 3/4 inch deep. This light has 10 LEDs and is a waterproof assembly. The mounting holes for this light are spaced 7 inches center-to-center, and 2-3/4 inches for the width. This light has 3 wires, red for the brake and turn signal, black for the tail light, and white is for ground.
    view full answer...
  • Is the Optronics LED Trailer Tail Light item # STL78RB DOT Approved?
    Since the Optronics LED Trailer Tail Light item # STL78RB is red it can be used as a third brake light. This light is DOT approved and can also be used as a rear turn signal. To use it only as a third brake light you will want to wire the black tail light wire and the red stop/turn light wire to one circuit. The white wire is ground. If you are needing to add a turn signal on the side of your trailer you will want to use an amber light like the item # STL78AB. I have linked a review video...
    view full answer...
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  • Could the # STL78AB and the STL78RB Be Used as Clearance Lights
    You can use the # STL78AB and the # STL78RB as clearance lights. The white wire of the light will get grounded and then you will run the black wire of the light to the running light circuit of your trailer. The red wire wouldn't be used.
    view full answer...
  • Matching Red and Amber Optronics LED Trailer Tail Lights
    We do have the matching red and amber LED trailer tail lights you are looking for. These are the same size (7-9/16" wide x 3-5/16" tall x 3/4" deep) lights with 10 diodes, and they hardwire in. So what you need are the following: - Optronics LED Trailer Tail Light - Red Lens # STL78RB - Optronics LED Trailer Parking Light with Turn Function - Amber Lens # STL78AB I've added links below to video reviews for you to check out as well if you'd like.
    view full answer...
  • Can Clearance Lights be Installed on Side of Trailer as Additional Turn Signals
    The DOT rules are typically that if the turn signal is facing the side of the trailer it needs to be amber in color like the part # STL78AB and then if facing the rear it can be amber or red like part # STL78RB. However, if the light also carries the stop light circuit it would have to be red. You would need to check with your local DOT to confirm this, but in the meantime I attached a help article on trailer lighting options as well. To do what you are looking to do would require you...
    view full answer...
  • How Does Trailer Clearance Light # STL78AB Wire to Clearance Light with Tail and Turn Signal
    The white wire of the clearance light part # STL78AB that you referenced is the ground, the black is for the running light circuit and the red is for turn circuit. Since standard trailer wiring has the brake and blinkers on the same circuit you'd need a signal converter to separate out just the turn signals for this. For that you'll need the part # 118158 wired up like the picture I attached.
    view full answer...
    Image 1 for
  • How To Install The Optronics 6-1/2 Inch Oval LED Trailer Turn Signal and Parking Light # STL78AB
    The wiring on the Optronics Sealed, 6-1/2 Inch Oval LED Trailer Turn Signal and Parking Light, part # STL78AB, is three wires. It is white for ground, black for parking light function, and red for turn function. You will not need an adapter to connect these lights to your trailer. These are surface mount lights that will attach to your trailer through the four mounting holes. The only other hole needed would be for the wires on the Optronics lights to go into for connection to your existing...
    view full answer...
  • Is Optronics Oval LED Trailer Turn/Signal/Parking Light # STL78AB Surface Mounted
    Yes, the Sealed, 6-1/2 Inch Oval LED Trailer Turn Signal and Parking Light, Flange Mount, 10 Super Diode, # STL78AB, is a surface mount light. The only holes will be for the hardware to mount the light on the motorhome. You may also be interested in the Chrome Accent Ring, # A78CB, to add a little quick and easy dress up to the lights and motorhome.
    view full answer...
  • Surface Mount Version of ST75AB Optronics Clearance Light
    The closest light we have to the part # ST75AB that is a surface mount is the part # STL78AB which I attached a review video for you to check out.
    view full answer...
  • Parts Needed to Convert a Trailer Side Marker Light to Running Light and Turn Signal
    On trailers, the turn signals and brake lights are combined. You could install the Vehicle to Vehicle Taillight Converter, # 118158, but your side marker lights must be dual function lights, like our Optronics Oval LED Turn Signal and Parking Light, # STL78AB. If your current running lights have only one wire, not including a ground wire, to power the light, it is not a dual function light. I have attached a link to all of our dual function amber LED lights for you to check out. The Vehicle...
    view full answer...
  • Recommended Amber Side Marker Light for Snowmobile Trailer
    I highly recommend the Optronics Sealed, Mini Rectangular LED Trailer Clearance, Side Marker Light # MCL95AB. This is an LED light which is 2-1/8" long x 1-1/8" wide x 1-1/16" deep and mounts by plated steel stud on base of light. It has gotten close to 200 reviews from our customers who have used it and a nearly 5-star review. I've added a link to a review video of the light for you to take a look at.
    view full answer...
  • Is There A Strip Light Available With an Amber Lens For Trailer Lights?
    The Thinline LED Trailer Tail Light is only available with a Clear Lens using Red LED's # STL59RCB or a Red Lens # STL59RB. Optronics does not manufacturer a strip light with amber LED's or a amber lens. The Optronics LED Trailer Turn Signal # STL78AB is going to be the closest light to this with an Amber lens.
    view full answer...
  • Wiring Optronics Oval LED Trailer Turn Signal and Parking Light as a Vehicle Front End Replacement
    When wiring the Optronics Oval LED Turn Signal and Parking Light, part # STL78AB, you will want to connect the red wire from the light to the turn signal wire from the vehicle and the black wire from the light to the parking light wire from the vehicle. Then you should ground the white wire from the light to the frame of the vehicle or another good ground source. This may not be an issue on the front end of your vehicle, but you may want to test the circuit you are attaching the red...
    view full answer...
  • Porch Light for Use on a Tear Drop Trailer
    Between utility light # BUL78CB and amber light # STL78AB the better option would be the utility light # BUL78CB. It will be brighter and the white light is definitely going to provide better visibility. We do also have lights designed specifically as porch lights such as # RVPL1C. I have included links to video reviews of these lights for you.
    view full answer...
  • LED Side Marker Lights to Replace Truck-Lite Model 60s on a Pumper Truck
    The LED side marker/turn signal light that is comparable to your Truck Lite model 60 is our Optronics LED lights part # STL78AB. It's 7-9/16 L x 3-5/16 W x 3/4 D. It's a flange mount as well as it is sealed, waterproof and corrosion resistant. Your current marker light, such as part # BU70CB, is 6-1/2 L x 2-1/4 W x 2-3/8 D. You may also be interested in the Optronics chrome accent ring, part # A78CB, to add a little quick and easy dress up to the lights and your Pumper. I included a video...
    view full answer...
  • Replacement Amber Trailer Light Options For Different Shape And Style
    For your replacement amber lens, we will have to go off of your style of light, color, and measurements. There are many lights that meet the standards you listed, but the measurement will help us with the replacement lens or replacement light you need. I've added a link to our page to assist you with finding the proper fit amber light/lens. We have various shapes and styles. You may be interested in Rectrangular LED lights, like the Rectangular LED Trailer Clearance and Side Marker...
    view full answer...
  • Replacement Fender for Shorelander Boat Trailer SRV1724
    Thanks for the information regarding your boat trailer, I was able to look up the tire size of your trailer in order to determine an appropriate replacement fender. I found that the trailer tire specified for your trailer was listed as a ST185/80R13. Therefore the trailer wheel is a 13 inch wheel with an approximate overall diameter of 24.4 inches. If your trailer tire is not this size please feel free to reply with an updated tire size and I can make additional recommendations for you....
    view full answer...
  • Surface Mount Amber LED Trailer Light Recommendation that Measures 6-1/2 by 2-1/4
    For a similar trailer light as the part # STL70AB that can be surface mounted you would want the part # STL78AB. I attached a review video for you to check out as well. Or you could use the bracket part # BK70BB and the # A70GB to install the # STL70AB.
    view full answer...
  • Amber Submersible Warning Lights for Trailer that Flash
    We have just what you need with the Buyers Products 24-LED Strobe Warning Light # 337SL66AC. This amber light flashes 4 times per second and is IP67 submersible. It comes with a grommet too that will allow you to install it easily in the fenders of your trailer.
    view full answer...
  • What are the Wiring Functions for the Directional LED Warning Light, # SLL72AB1
    If you are referring to light # SLL72AB1, the white wire is ground and the red wire is power. The black wires allow two of these lights to flash together. The power wires can be connected to an accessory circuit that is always on when the vehicle is on, or set up on a switched system. The correct wiring harness for this light is # A45PB and the correct grommet is # a70gb.
    view full answer...
  • Which Wiring Harness Will Be Needed to Install the Optronics GloLight LED Trailer Light STL178RFPB
    The proper hardwire wiring harness for the # STL178RFPB GloLight LED trailer tail light is the # A47PB. A great and similar style side marker/clearance and turn light is the # STL78AB, this will already have the proper wires to install on your trailer. If you prefer it to be a GloLight like your tail lights we do have one from Optronics # STL111AB. The wiring harness you will need to install the GloLight # STL111AB to your trailer is part number # A47PB. Since the GloLight LED doesn't...
    view full answer...
    Image 1 for
  • How to Install 3-Wire Optronics Oval LED Trailer Turn Signal and Parking Light STL78AB
    The Optronics Oval LED Trailer Turn Signal and Parking Light # STL78AB uses a separate white ground wire along with the two power input wires, black for parking and red for turn. Odds are your original incandescent lights used their mounting hardware to establish the ground so you'll want to find a suitable bare metal surface to make that connection using a ring terminal like # DW05737-1 (order two). You will also want to apply dielectric grease like # 11755 to that grounding point to...
    view full answer...

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Info for this part was:

Employee Robert G
Expert Research:
Robert G
Employee Michael H
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Employee Jeff D
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Employee Jameson C
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Employee Kathleen M
Video by:
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Employee Cole B
Installed by:
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Employee Wilson B
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Employee Brian T
Updated by:
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