Tail lights with two bulbs

[JX007]

Hi everyone,

I have a Trillium 1300 1979 I purchased last fall and I am doing some work on it. Today I started changing all lights on it for new ones. When disassembling the tail lights, I noticed my existing ones have two bulbs (4 wires) in them but my new ones only have one bulb (3 wires). Any idea why? I will do further testing if I have to, but just wondering if someone can shed some light on this...

Tks a lot in advance.

[Dave Fish]

I guessing that on the old one, the bulbs are single filament with separate bulbs for turn/stop and tail lights. The two white wires are probably ground. If there are wires on the left and right that are the same color, they are probably for your taillights.

If I'm correct, you just need to figure out which wires on your new lights are ground, turn/stop, and tail and you'll be good to go.

You should hook the trailer to the car and test the circuits with a tester to verify my assumptions.

[Nicolas]

When it comes to wiring, never make the assumption that what should be is. Good advice to use a tester and hooking up to the car to test the circuit. Sometimes the wiring colours don’t match up or the previous owner ran a new wire of a different colour.

You just need to eliminate the extra ground wire and hook up the two coloured wires to the single, double filament bulb holder correctly. Ideally, the brown wire is the taillight wire; the yellow is the right stop/turn light; the green is the left stop/turn light.

[mary and bob]

Did the original lights have a separate bulb for the turn signals. If you have a 4 pin plug, that would require the converter for the tow vehicle.

[Nicolas]

Good point. Is the trailer connector a 7-pin or 4-pin? One would think that as a travel trailer it would be 7-pin but, if not, then the wiring harness would be different colours.

[ThomasC]

Originally Posted by Dave Fish

I guessing that on the old one, the bulbs are single filament with separate bulbs for turn/stop and tail lights. The two white wires are probably ground. If there are wires on the left and right that are the same color, they are probably for your taillights.

If I'm correct, you just need to figure out which wires on your new lights are ground, turn/stop, and tail and you'll be good to go.

You should hook the trailer to the car and test the circuits with a tester to verify my assumptions.

This is correct. The only additional thing to check is the brightness of the two filaments. Apply 12 volts to each filament and notice the brightness. The brighter is brake/turn signal, and the dimmer is tail lights.

[Wayne Collins]

As long as you're changing lamps, go with a LED unit with tail, stop, turn and 4 way flasher capability. They give off brighter light, and will not burn out as fast. and don't take as much amperage.

[Radar1]

A few possibilities.
One, is that you had separate bulbs for the running and signal lights.
Two, is that you had a combined bulb for running lights and brake lights, and another bulb for turn signals.
Three, is that you had backup lights on the old setup but not on the new setup.

Might even be more possibilities but I can't think of them right now.

[ThomasC]

Originally Posted by Wayne Collins

As long as you're changing lamps, go with a LED unit with tail, stop, turn and 4 way flasher capability. They give off brighter light, and will not burn out as fast. and don't take as much amperage.

I was reading in the past year about the speed of led brake lights. They come on faster so anyone following you has more time to brake. It is a measurable amount and makes your vehicle safer.

[TomA]

In the mid 70s, "Foreign Cars", mainly European cars, started coming out with amber turn signals. This required the separation of stop light bulbs from turn signals. So, we installed these extra bulbs as an option on the trailers. There is yellow wire in all Trilliums to serve as the brake light light circuit. It runs from the front Bargman connector to each tail light. There is a Trillium Wiring Guide in the document section of this website which will help you.
Today, you can buy an adapter to be wired into the tow vehicle so these extra bulbs aren't necesary.

Tom

[Rick In Mn]

https://trilliumrv.files.wordpress.c...trlrwiring.pdf

My scamp has extra bulbs too, I wired it to the back up lights.
It helped

[Francesca Knowles]

Originally Posted by TomA

In the mid 70s, "Foreign Cars", mainly European cars, started coming out with amber turn signals. This required the separation of stop light bulbs from turn signals. So, we installed these extra bulbs as an option on the trailers. There is yellow wire in all Trilliums to serve as the brake light light circuit. It runs from the front Bargman connector to each tail light. There is a Trillium Wiring Guide in the document section of this website which will help you.
Today, you can buy an adapter to be wired into the tow vehicle so these extra bulbs aren't necesary.

Tom

Really fascinating bit of history there Tom, thanks. I'd always thought that yellow wire was there to allow for the addition of backup lights, an option I've often thought about adding.

[TomA]

Francesca - Yes, a good idea today.
Back then, there was no way to add back-up lights to the tail light platform. But, there was a need for separate brake lights. This was a simple solution for us.
With the elimination of the old Bargman light, you can add back-up lights instead of stop lights. (With the car adapter if needed, and a variety of fixtures to chose from.)
Tom