How to fix taillights and side marker lights?

[JeffE]

I've got a 75' trullium 1300. The taillights and side marker lights need to be replaced. I am not looking to go all original and am not wanting to hook up the heater, fridge, sink,or interior lights. I just want to bypass all the old wiring with new and get it on the road. Just a dry place to sleep in with no amenities. I wanted to use a utility/boat trailer light kit but I think the lights rely on a metal frame for the ground. So I think I would need to get lights with a ground wire. Am I correct on this? Any suggestions for how to get it street legal again?

[AC0GV]

First, most RVs have three electrical systems. The 120 VAC to run the air conditioner etc. The inside 12 VDC to run lights, water pumps etc. from the house battery.
The one you need for highway safety is the third, 12 VDC from the tow vehicle, for brakes, marker lights, and the stop/turn, the lights are easy to find at any auto parts or farm and barn store. DO not buy them from Harbor Freight if you plan to keep it for years. Chances are that your wiring is all in place and that it be an easy change. Just pick new lights that will cover all the old holes and seal well. The side lights will have 2 wires and the stop/turn/tail will have 3. Have fun.

[k corbin]

The trailer lights are grounded to the frame, not to the fiberglass shell. There will be a ground wire to connect to inside of your new lights. You will need to crimp a ground wire to those and then run it along with your other wires and then attach to your frame. Just look all this stuff up on youtube, there will be videos about it. If in doubt go to your auto parts or marine supply store or Home Depot. All of them will have the supplies you need.

[thrifty bill]

Wire harness is posted in the document center. Its really straight forward.

Original has ground wire that goes all the way to tow vehicle through the plug.

[Lockman]

Jeff,


While Kenneth is correct on the side marker lights, you need 4 wires for the Tail =1, Brakes/turn L/R=2 and gnd=1.


Jack

[Terry in Fowler]

If you're taking the ground to the frame make sure the connection of the ground wire from the TV to the frame is good and not corroded. Since these connections are often in the weather they tend to corrode. I had it happen couple of times over the years. You don't want to depend on the hitch for grounding. When lights start flashing on and off intermittently it is often the hitch making and braking connection indicating a bad wire connection. If I'm running new wires I usually run a ground wire with them.

[AC0GV]

Originally Posted by Lockman

Jeff,


While Kenneth is correct on the side marker lights, you need 4 wires for the Tail =1, Brakes/turn L/R=2 and gnd=1.


Jack

Each stop/turn/ tail light requires 3 wires when he goes to buy them in the store. And the RV will have that many running to each light on the trailer.

[floyd]

Originally Posted by k corbin

The trailer lights are grounded to the frame, not to the fiberglass shell. There will be a ground wire to connect to inside of your new lights. You will need to crimp a ground wire to those and then run it along with your other wires and then attach to your frame. Just look all this stuff up on youtube, there will be videos about it. If in doubt go to your auto parts or marine supply store or Home Depot. All of them will have the supplies you need.

Best if not grounded to the frame.
The DOT wiring on the Trillium would best be replaced with the ground run all the way through a fourth wire. The harness is best run through the inside of the trailer.

You can buy a four wire harness designed for trailer wiring for a four plug.
It is

White(ground),
Brown (tail/running lights)

Yellow ( brake/ left turn)
Green ( brake/ right turn)


All ground/returns through the White
All tail/running/side lights through the Brown

Below is a Trillium which I did before LEDs were popular. Shown here as an example...
I suggest replacing all lights with LED for both brightness and dependability. observe polarity.

[Byron Kinnaman]

Originally Posted by k corbin

The trailer lights are grounded to the frame, not to the fiberglass shell. There will be a ground wire to connect to inside of your new lights. You will need to crimp a ground wire to those and then run it along with your other wires and then attach to your frame. Just look all this stuff up on youtube, there will be videos about it. If in doubt go to your auto parts or marine supply store or Home Depot. All of them will have the supplies you need.

WRONG.... Not grounded to the frame. The only thing that needs to be or should be grounded to the frame in the Green (Safety Ground) wire form power cord. There should NOT be current going through the frame.

[gordon2]

First, since nothing is really grounded (to earth ground) and non-electricians will be confused by the reference to "ground," I will refer to it as the DC negative.

While many trailers use the metal frame as an electrical conduit for the DC negative power, this is not the best way to do it. The connections to the frame are subject to corrosion and failure, and as mentioned, if the only DC Negative connection from the tow vehicle to the trailer is through the frame via the hitch, then it is almost sure to fail. If the trailer's frame is part of the circuit then there should be a wired connection from the tow vehicle to the trailer's frame via the umbilical cord, but sometimes there is not or it fails, so the only connection left is via the hitch ball. Thats bad, esp if the brakes rely on this connection.

Scamp uses the trailer frame as a common DC negative connection for the brakes. One of the two brake magnet wires from each wheel is attached to the trailer's frame. The trailer's frame is attached to the tow vehicle's negative DC power via the umbilical. But this can fail, and has failed for some, so one of my priorities was to supplement this connection with separate wiring from the tow vehicle to the brakes on the DC negative side. You can leave the connection for the DC negative to the frame also if you wish since the DC negative or ground side is a common connection among all the DC lights, brakes, etc... However if there is a direct wired connection, and if the frame connection fails (or does not exist at all), then the current flow continues.

IMHO the only reason to use the frame as a conduit for the DC negative current is to save a very few dollars on wire.

[thrifty bill]

+10 its actually DC negative, not ground as I called it earlier.

[floyd]

Originally Posted by thrifty bill

+10 its DC negative, not ground as I called it earlier.

Never mind that every automotive mechanic has referred to the negative side as "ground" since the positive side quit being ground in the early '50s.
Now do we insist on "hole theory" or can we just stick with electron flow?

[gordon2]

Originally Posted by floyd

Never mind that every automotive mechanic has referred to the negative side as "ground" since the positive side quit being ground in the early '50s.

Yes, the use of the term DC Negative is intended for those readers of this forum whom are not automotive mechanics who are familiar with 64 or more years of automotive electrical theory..

[JeffE]

Thanks to all that have offered up your hard earned knowledge. The more I look at it the more its all starting to make sense. At first it just looked like bunch of spaghetti! Thanks again for all your help.

[floyd]

Originally Posted by gordon2

Yes, the use of the term DC Negative is intended for those readers of this forum whom are not automotive mechanics who are familiar with 64 or more years of automotive electrical theory..

[getaway1]

Hello I would use solder on all wire connections when you work on your trailer. Two reasons for this vibration and corrosion. I would use the flat 4 wire trailer wire kit with the molded plug in on one end. Please note that some kits don't have the white wire full length only a short 6" piece near the plug. You will need to tap in for the front marker lights brown wire and white . Refer to the wiring diagram on this site for information on this. The rear markers can be tied in to the tail light connection. The yellow and green wires are for turn signals and brake lights. The brake lights share both yellow and green to operate. They require no modifications in any way to the system. (same as your TV ) If you use LED lights they are polarity connected if you reverse the wires they don't light at all. Watch for this when working. If you use the matching wire colors you should be fine . Test all the lights prior to soldering and taping (shrink wrapping). Good luck ! I hope this may help you out ! Happy Camping ! Duane

[TomA]

FYI Members


All Trilliums have a white ground wire (12v. negative) running through the trailer.
This is for 12v automotive lights, interior lighting, and 12v. equipment.
The likelihood of this wire being bad is remote, but can be tested if there seems to be trouble. It is not necessary to 'ground' to the frame. First is to ensure the white ground wire has a good connection to the white terminal in the front connector. Then, be sure the car connector white terminal has a good ground to the tow vehicle.:
From here, all the various functions can be tested by volt meter or 12v test light.
See the attached wiring guide, which also includes directions on wiring the tow vehicle.


Mods: Perhaps this pdf should be a "sticky" on this site.


Happy Camping
Tom

[Doctor Harold]

Originally Posted by floyd

Never mind that every automotive mechanic has referred to the negative side as "ground" since the positive side quit being ground in the early '50s.
Now do we insist on "hole theory" or can we just stick with electron flow?

I'm one of those old-timers who call it ground, although I've had a few cars that were from the other side of the pond, and were neither negative nor positive "ground"!

--Harold

[TomA]

Floyd:
"hole theory" - LOL.... You're showing your age, me too.


Harold: Beautiful car... But, where's the hitch?

[Doctor Harold]

Originally Posted by TomA

Floyd:
"hole theory" - LOL.... You're showing your age, me too.


Harold: Beautiful car... But, where's the hitch?

Hitch? I wish!

I had that car for 15 years, sold it and it shipped to Germany in 2016. That 4.2L engine would have pulled the Scamp like it wasn't even there. It had legs!

I've actually daydreamed about putting a hitch on my current daily driver, but I'm not sure my Scamp will corner well at the speeds this car likes to go.

--Harold