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Optronics Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Amber Lens

Optronics Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Amber Lens

Item # MC31AB
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MC31AB - Non-Submersible Lights Optronics Clearance Lights
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In Use/Installed

4" x 2-1/16". Waterproof, incandescent trailer light serves as a clearance or side marker light when properly mounted. Built-in reflex reflector. Surface mount to trailer - hardware not included. 1-Wire design. P2 rated. (1) 194 Bulb. Lowest Prices for the best trailer lights from Optronics. Optronics Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Amber Lens part number MC31AB can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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  • Reviews (16)
  • Q & A (5)
  • Videos (2)
  • Photos
  • Why etrailer?

Optronics Trailer Lights - MC31AB

  • Clearance Lights
  • Oval
  • Incandescent Light
  • Amber
  • Surface Mount
  • 4L x 2W Inch
  • Optronics
  • Non-Submersible Lights
  • Rear Clearance
  • Side Marker

4" x 2-1/16". Waterproof, incandescent trailer light serves as a clearance or side marker light when properly mounted. Built-in reflex reflector. Surface mount to trailer - hardware not included. 1-Wire design. P2 rated. (1) 194 Bulb.


  • Incandescent trailer light serves as a clearance light or side marker when properly mounted
  • Built-in reflex reflector removes the need for a separate reflector
  • Inandescent bulb can be easily replaced
  • Durable polycarbonate housing and lens
  • Amber snap-on lens over incandescent bulb
  • Compatible with 12V DC systems
  • Surface mount to trailer - hardware not included
  • Single wire design grounds through mounting hardware
  • DOT compliant
  • P2 rated


  • Dimensions: 4" long x 2-1/16" tall x 1-3/32" deep
  • Distance between mounting holes (center on center): 3"
  • Bulb type: 194
  • Power draw at 12.8 volts: 0.2 amps
  • 3-Year warranty

Optronics MC31 Series Marker Clearance Light Dimensions

P2-Rated Lights

Diagram of light spread for P2 rated light

A P2-rated light produces a 45-degree angle of light to either side of its centerline for a total of 90 degrees of coverage. This beam pattern can be seen straight on, but it cannot be seen clearly from the side. So this type of light can be used as either a side marker light or a clearance light, but it cannot function as both. If you need both functions, then you must install 2 separate lights on your trailer - one as a front or rear clearance light and one as a side marker light.

MC31AB Optronics Trailer Clearance or Side Marker Light w/ Reflex Reflector - Incandescent - Oblong - Amber Lens - P2 Rated

Alternate part number: MC-31AB

California residents: click here

Video of Optronics Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Amber Lens

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Optronics Oblong Trailer Clearance, Side Marker Light Installation

Speaker 1: Today we're going to be taking a look at the Optronics oblong trailer clearance and side-marker light with reflector, offering the amber lens and black base. Part number is MC31AB.Here you can see our light installed. You'll notice it has a black base on it. Most of the lights in this size category are going to have a white base. It can add a pretty nice look to your trailer, if you have a trailer that's maybe a black, or a red, gray, something like that, and you don't want a standard looking light on it.It offers a single incandescent bulb. It also offers the reflectorized lens, which you can see here.

Basically, that stands in place of the separate reflectors. So it's DOT compliant, as far as not needing a separate reflector anywhere. And when the lights are off, if you we're to hit it with your headlights, it lights up so you'll be able to see where your trailer's located.Now incandescent bulbs such as this has been the industry standard. You see it on just about every type of trailer out there. If you're just replacing one light, I'd find one that matches, and go back with that.But if you're changing the lights on your trailer, a lot of people are going over to LEDs, basically because they're much easier to use.

You don't have to worry about changing the bulb out. They last many times longer. Also, they give you a cleaner, and brighter light. It can really update the look of the trailer.And as an added benefit, they don't draw as much power. So we don't have to worry about that element heating up in there.

We don't have to worry about drawing all that power through our vehicle.The light is SAE, and DOT compliant. So it's going to work for all of your needs, whether you're mounting it like we have up here, as a clearance light. Or if you have it down as a side-marker light.Now this light's designed with three inch centers for the mounting location. So that's going to match up with all the standard, oval-shaped clearance lights out there. So it should be a very easy replacement for you.Another nice thing about the light is like with most of them, this lens is replaceable.

So if for some reason, a rock hits it, or it gets damaged, instead of replacing the entire base and lens, you can just replace the lens.Now to begin your installation, of course you want your old light removed. We're going to take our base here, you can see we've got a single wire coming off. It's what they call a single wire design. Most applications . Just strip that off. In most applications, this is designed to work with a metal base. You're going to be attaching it to metal.When we have fiberglass like this, we can't get a good ground made through there. So we'll show you how this will also work with a two-wire set up, so whether you've got one or two wires, it should work out fine for you.Now for the one wire guys, you're just going to strip back your power lead wire. And we're going to use a butt connector to make our connection there, part number DW05744, if you don't have them. This is a heat shrink butt connector. This does an excellent job of keeping any moisture, or dirt getting in there, leading to corrosion.Get that crimped down on. And then the other side we'll crimp to our light. At that point, with a single wire, you're ready to mount it. You can see that metal tab right there. That's what establishes your ground as you put your fastener through.With our setup, since we are doing a two-wire, we're going to bring our ground wire through, strip it back, and we're going to add a ring terminal to that. Just a small diameter opening there, get it crimped down.Now to shrink this down, you'll want to use a heat source. You can use a mini torch, you can use a heat gun or a lighter. Just need to be careful not to overheat it. Just gently heat it up, and allow it to shrink.When it does shrink, it's going to look like the wire gets larger, almost as if it's magnifying it. See where it's starting to do it there. Just take that out to the end, then you'll have a little bit of clear gel that'll come out. You want to do that on both sides of your connector there, so it looks just like that.Now we'll just want to re secure it with our existing hardware. When we do this side, we want to ensure that our ring terminal is placed over that ground strip right there. Now with those secure, just going to place our lens over the top, and press down firmly, get it clicked in place.Now to test out our light, you can simply connect your trailer to your truck, turn on the running lights, or use a trailer tester like what we're doing. And it seems to be working just fine.That's going to complete our look at the Optronics oblong, trailer clearance and side-marker light with reflector. Part number MC31AB.

Customer Reviews

Optronics Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Amber Lens - MC31AB

Average Customer Rating:  4.9 out of 5 stars   (16 Customer Reviews)

4" x 2-1/16". Waterproof, incandescent trailer light serves as a clearance or side marker light when properly mounted. Built-in reflex reflector. Surface mount to trailer - hardware not included. 1-Wire design. P2 rated. (1) 194 Bulb.

- MC31AB

amazing quality for price - very happy !!!! 703107

- MC31AB

Parts came ahead of schedule, perfect fix, easy install. Saved time vs repair and parts. I always go to etrailer for my one stop parts. Thanks 696748

- MC31AB

Items arrived sooner than expected, installed easily and looks and functions great. I will use etrailer again and recommend .Tammi was very helpful. Aloha from Hawaii 694564

- MC31AB

Very Happy 647143

- MC31AB

Sturdy base with double mount holes for stable installation. 592958

- MC31AB

Very nice lights, at a very good price. Arrived quickly... 454549

- MC31AB

Works perfect and can't beat the price 419169

- MC31AB

Great product and price. 371000

- MC31AB

Website easy to navigate, prices good and quick delivery. All good. 349468

- MC31AB

Good quality for the price. Delivery time was excellent. Great service on the question I had. Will buy from etrailer again. 317890

- MC31AB

Great and fast service. Got just what I needed. I will order from you again, Thanks 244325

- MC31AB

etrailer is a good outfit, items are usually in stock and ship quickly. The lamps are your standard one wire type that grounds to the skin of the trailer with the mounting screw. The lamp is a 194. The wire protrudes about 4" outside the back of the lamp. They appear to be mountable in any orientation. 222430

- MC31AB

Lites arrived in a timely fashion. Good quality, whish they were brighter. 193446

- MC31AB

the lights were delivered on time. will be installing all 14 on my camper trailer. thanks for the help and videos they were very informative art 95504

- MC31AB

bought these for my home built trailer - great product - great price. 56506

- MC31AB

great service and fast shipping good quality. i like the black mounting instead of the traditional white 5486


Ask the Experts about this Optronics Trailer Lights

  • Measuring to Ensure Clearnace Lights Fit Yacht Club Trailer
    There is a way for you to find out if the Oblong Trailer Clearance, Side Marker Light with Reflector # MC31AB fits your 2006 Yacht Club trailer, though we do not have any parts lists for years, makes and models of trailers that would allow us to know this. Instead, you will simply need to take a measurement; Clearance Light # MC31AB is surface mounted with mounting hole spacing 3" apart on center so if your trailer has that mounting hole spacing it would work for you.
    view full answer...
  • Clearance Light Recommendation for Trailer # MC38AB or # MC31AB
    Between the clearance lights # MC38AB and # MC31AB the difference is mainly aesthetic. I personally like the black base and rounder edges of the # MC31AB so that is what I would go with. You would need to use bolts or screws to secure the base of the light to the trailer and then pop the lens on top of it to install it.
    view full answer...
  • Picking Out Replacement Taillight Bulbs for 1990 Jayco Popup Camper
    I looked up a few pictures of a 1990 Jayco popups and found that they all seemed to have taillights like the # 30-92-003 that you referenced. This light takes a 1157 bulb like the # A1157B for an incandescent bulb or the part # DG52624VP for an LED version that will be brighter and last longer. The side clearance lights appear to be the part # MC31RB for red and # MC31AB which use 194 bulbs like the # A194B.
    view full answer...
  • Replacement Lens for Optronics Trailer Clearance Light MC31AB
    The lens you need is # A31AB. It fits clearance light # MC31AB which is 4 inches long, 2-1/16 inches tall, and 1-3/32 inches deep overall. Optronics has an MC and MCL series but not just an M and the lens is not replaceable on the MCL version of the light so that is why # A31AB would be the correct lens.
    view full answer...
  • Availability of a Oval Trailer Clearance Light with a Black Base
    The closest thing we have to a version of the Oval LED Trailer Clearance, Side Marker Light # MCL31RB that you referenced with a black base in an amber and red lens would be the Red Oblong Trailer Clearance, Side Marker Light # MC31RB and the Amber Oblong Trailer Clearance, Side Marker Light # MC31AB. Both these lights have black bases, but they have incandescent bulbs instead of LEDs.
    view full answer...

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Info for this part was:

Expert Research:
Jameson C
Updated by:
Laura H
Updated by:
Sarah W
Updated by:
Brian T
Installed by:
Cole B
Installed by:
Randy B
Video Edited:
Chris R
Video by:
Zach D

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