Left tail light keeps failing

[Xspook]

On my Triton trailer, the tail light function on the left light keeps failing. Brake and turn work with no problems on that light. The right light works with no problems. When I replace it, it initially works fine. After a few "dunks", the tail light will fail. All other lights work as expected.

The lights I'm using: https://www.northerntool.com/shop/to...6778_200466778

Would replacing with LED's "fix" this?

[K447]

The left and right lamp assemblies are the same. As you know, you can easily remove the lamp from the rubber grommet by pressing in one side until it swings inward, then wiggle the lamp out of the rubber grommet.

Swap the left and right lamps. If the 'failed' lamp works when connected to wiring on the right side then the lamp itself is ok.

Most failures in trailer lighting are caused by loose connections, corrosion or chaffed wires.

Inspect each pin connection on the on the left side wires. Look for signs of heat, corrosion, looseness when plugged in.

Also look at the wiring for fraying or a spot where the insulated wire runs across a rough metal edge inside the trailer frame.

On the Triton trailers the 'ground' is wired all the way to the flat four pin connector at the tongue. The ground wire color is white in trailer wiring.

Brown wire is connected to all the running lights including both rear tail lights.

Yellow wire is just for the left left corner turn signal. Green for the right rear turn signal. Both wires are powered for braking.

Also inspect the flat four pin connector at the tongue. It is not uncommon for the pins to corrode or weaken and create a poor contact. Check both the tow vehicle and the trailer connectors.

Absolutely LED lights are 'worth it'. Not only do they consume a lot less power, they do not heat up nearly as much as old-school incandescent bulbs. LED lamps are not affected by normal road vibration, no fragile bulb filaments to break. LED lamps should last almost forever, if you buy good quality marine grade LED lamps.

[Xspook]

Swap the left and right lamps. If the ‘failed’ lamp works when connected to wiring on the right side then the lamp itself is ok.

The lamp is definitely failing. When I removed the failed lamp from the left side and moved it to the right, the problem "followed".

I'm basically trying to be lazy and hoping that replacing with LED's would stop the problem.

So, would an LED light fail similar to what's happening with the incandescents? If I switch to LED's would the problem keep happening?

[K447]

The lamp is definitely failing. When I removed the failed lamp from the left side and moved it to the right, the problem "followed".

I'm basically trying to be lazy ...

Look more closely at the wire harness where it connects to the taillight. I suspect you will find a weak/corroded/burned contact.

That poor contact is heating up the electrical joint and the heat is conducting into the tail lamp, causing it to fail.

[Xspook]

Look more closely at the wire harness where it connects to the taillight. I suspect you will find a weak/corroded/burned contact.

That poor contact is heating up the electrical joint and the heat is conducting into the tail lamp, causing it to fail.

I replaced the connectors, but it's still failing (just the tail light function; brake and turn work with no problems).

old connectors:



new:



The new connectors were attached to the main wires via heat shrink butt crimp terminals similar to this:

https://www.walmart.com/ip/200PCS-Butt-Crimp-Terminals-Insulated-Connectors-Heat-Shrink-Tubings-Set/811879572

The connectors for the side marker light were not replaced, but it has also failed.

[K447]

Are the new lamps, which also failed, LED or traditional incandescent bulbs?

[Xspook]

Are the new lamps, which also failed, LED or traditional incandescent bulbs?

New, non-led. Would whatever is causing this make LED's fail too?

[K447]

New, non-led.

Would whatever is causing this make LED's fail too?

I was thinking the other way around. A good quality LED lamp may not fail.

LED is generally much more robust, resistant to damage from vibration, voltage flickering, moisture ingress.

Have you verified the grounding circuit is indeed 100% electrically solid?

Some trailers use the trailer frame for ground. Each place the white wire is bolted to the frame is an opportunity for rust/corrosion. A bad electrical connection can cause constant/rapid flickering as the trailer rattles down the road. Incandescent light bulbs do not like a flickering power flow. *

Another possibility is something is causing excessive vibration in that corner of the trailer. Perhaps a bent wheel, out of balance tire? Seems remote, but possible?


* If you do replace the trailer wire harness, look for a harness that runs all the white 'ground' wires all the way up to the flat four connector, with perhaps a single white wire connection to the trailer frame at the tongue.

[TimeBandit]

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Would replacing with LED's "fix" this?

Yes, LEDs should be a lot more robust - typically sealed better (from factory) since they never need be serviced/opened by the end-user to change a bulb.

Sometimes adding dual guide-posts (PVC), then mounting the lights on-top to keep them out of being dunked ÔÇô not for the lazy

Pulling farts out of the sky here - since the failure moved when you swapped sides, one possibility is the housing seal being bad. I've seen cold water contacting a hot bulb blow bulbs repeatedly. Trapped humidity/moisture corroding the bulb socket. Also the bulb socket itself might have a defect. Also could be the wires attached to the fixture ÔÇô sometimes water will wick-up deep up inside the insulation, so hard to see the corrosion.

Side-tip : not to "crimp" your connections. Rather strip the wire ends and use twist-on wire-nuts, fill, twist-on, then back-fill them with silicone/RTV to keep it water-proof.

-..
Some trailers use the trailer frame for ground. Each place the white wire is bolted to the frame is an opportunity for rust/corrosion. A bad electrical connection can cause constant/rapid flickering as the trailer rattles down the road. Incandescent light bulbs do not like a flickering power flow. *
-..

I personally loathe that the industry's standard wiring practice is to utilize the chassis as the ground-plane. So on all my trailers, I deliberately run a ground wire to all lights, thus not use the frame. This has eliminated 90% of the problematic issues often encountered.

[pops]

Best solution for splicing wires on a trailer is not use crimp lugs or "wire nuts". Solder the connections and seal with the glue filled heat shrink tubing, extending 1/2" on either side of the solder joint. This will seal the soldered connections better than other methods.

If crimp lugs can't be avoided, use them if need be and seal with the glue filled shrink tubing over the connectors and at least 1/2" of wire on each end, or at least use silicone..

[K447]

... serviced/opened by the end-user to change a bulb.

...

Hang on, is it just the bulb that is being changed again and again, or the entire lamp assembly?

If just the bulb is being replaced, I suggest replace the entire lamp assembly.

A bad/corroded/whatever lamp socket can repeatedly mess up new bulbs.

Install a new LED lamp assembly, marine/boat trailer rated. Sometimes these are labeled 'sealed'.

[Xspook]

Hang on, is it just the bulb that is being changed again and again, or the entire lamp assembly?

If just the bulb is being replaced, I suggest replace the entire lamp assembly.

A bad/corroded/whatever lamp socket can repeatedly mess up new bulbs.

Install a new LED lamp assembly, marine/boat trailer rated. Sometimes these are labeled 'sealed'.

I've been changing the entire assembly.

I'll swap out with LED's and see what happens.

[TimeBandit]

Is it possible that when you mount that left fixture, that be something not flush (aka warping the light fixture) with the install perhaps??
I just cannot see a way (even intentionally) why one side would fail more than the other. There's been stranger things... like seeing roulette hit on black 6 times in a row.
Yes go LED, again because these are usually sealed better.

[Spades]

I would check for over-voltage on that lead (with engine running). If its over then the new LED lights could burn up also, although the LEDs will have a wider acceptable range

[K447]

I would check for over-voltage on that lead (with engine running). ...

On a trailer all the running lights are powered by the same single pin on the flat connector at the tongue.

I struggle to see how just one trailer lamp could be affected by high voltage (something over 15 volts?) from the tow vehicle, nor how such high voltage could exist without causing all sorts of possible issues within the tow vehicle.

This appears to be a Triton trailer, with the lamp assembly mounted in a rubber grommet. Generally these do not cause much trouble, especially the LED versions.

I have had occasional issues with loose connections where the harness pins plug into the lamp socket. Even a few cases where one of the wire pins falls right out of the socket. The loose end can then short to the trailer frame, perhaps intermittently.

I still suggest switching to good quality LED lamp module(s). Just less fragile both electrically and mechanically.