need help with trailer lights

centerline · Aug 9, 2012

check the fuses under the hood of your tow vehicle.... if you have everything except brake lights, its a fuse or your brake light switch at the pedal.

Knuttle · Aug 10, 2012

Do the brake lights work on the tow vehicle? If so it is probably something in the way you have the trailer wiring interconnected into the wiring of the tow vehicle.

Your tow vehicle may not have a standard wiring system as the new harness expected.

caguy · Aug 10, 2012

U-haul is usually really helpful,.and can likely solve the mistery in a few minutes, they do this stuff all day long. You will probably spend all day on this one job.

Freedom77 · Aug 10, 2012

HI Carolyn. Long time no hear. How are things in the rainy north. 115 here in Sin City. It ain't hell but you can see it from here!! What kind of vehicle do you have. Generally the brake lites and turn signal are on the same circuit??? See postings on let there be lite for some good ideas from other members.

DBarry73 · Aug 10, 2012

On the trailer wiring Green is right, yellow is left, brown its your trail lights. The brake lights & turn signal is the same circuit. White is your ground. On the lights them selves they usually have black for tail lights, red for stop/turn & white for ground. If your making a light bar find a fence company that does vinyl fencing and you can use a piece of the vinyl fence board. It looks alot nicer than wood.

walt · Aug 10, 2012

A bad ground connection could be causing this. Try running a direct wire from the ground on the tail lights to the ground on the trailer electrical connector (white to white).

When I replace lights on a trailer, I dont remove the old wires, just bundle them together and use them for the ground wire - and usually also tie to the trailer chassis.

DBarry73 · Aug 10, 2012

That sounds like a short., it could even be a bulb shorting out

tkanzler · Aug 10, 2012

Start at the beginning. Check output at the vehicle receptacle between the ground (the odd one) and the furthest (green/right turn/brake) and between the ground and the second furthest (yellow/left turn/brake) while someone steps on the brake. With the turn signals off, they should be hot when someone steps on the brakes, and off course, cycle whenever the turn signal that corresponds to it is on.

If all is well at the vehicle receptacle, as I suspect it probably is (but would check, as it only takes about a minute), then the problem is in the trailer or light board wiring, as as walt suggested, it sounds like a ground problem.

Model 70 · Aug 10, 2012

Might check output at the connector where the trailer plugs into the tow vehicle. With check light or meter probe white as ground and brown with lights on tow vehicle turned on. You should have 12.5 volts or better. Check turn and brake lights on the green and yellow wires. If you are not getting 12.5 or better voltage you may need to check for existence and condition of tow harness adapter. I replaced mine while visiting in Connecticut prior to pulling the V-21 back to Oklahoma.

Squidd · Aug 10, 2012

You need to run a seperat ground wire all the way back to your "light board" and connected to each light to complete the circut...

DBarry73 · Aug 10, 2012

Are you using LED lights or regular incandescent lighting? I personally like LED cause they have a long life span & require less power. A really easy solution to your problem would be to go buy some tow lights from u haul or tractor supply. You would have to connect them together or rig something to stick them to with the magnets or you could take the magnets off and bolt them on your board. Tractor supply had a wireless set for around 100 bucks last time I was in there. No wires to mess with. They run on batteries.

Model 70 · Aug 10, 2012

Squidd said:
You need to run a seperat ground wire all the way back to your "light board" and connected to each light to complete the circut...

This poster is correct. No ground path through a Wooden board.

Model 70 · Aug 10, 2012

Model 70 said:
This poster is correct. No ground path through a Wooden board.

Now that I think about it, you must already have a ground path established or there would not have been any lights at all. Need to get back to the voltage check at the tow vehicle connection.

Squidd · Aug 10, 2012

Needs a ground..

Lights will backfeed thru clearance circut or brake circut, but not when both are on at same time...

Knuttle · Aug 12, 2012

Ground

Save your self a lot of hassle and run a ground wire to each fixture whether we are tallking about fixtue on a board or on the trailer its self. One of the first thinks I remember when Dad was pulling a travel trailer was him trying to get the ligths ground so they worked right. The was standard procedure before we went camping and returned home.

For several years after I got the boat I tried the grounding through the frame, About 20 years ago I ran a ground to each fixture, and Ihave not had a problem since. After sitting for some time after we moved, I can go out an plug the lights into the car and all of them will work.

PS Make sure you include the tailler in the ground system.

MrBill_FLL · Aug 13, 2012

^ 1+

run the ground back to the car. ground is always a problem.

seaStan · Aug 13, 2012

I use a pair of removable trailer lights that hold on with magnets. I got tired of the things always not working. Now I can just take them off when I,m putting the boat in the water or have it parked at home. They can be used on any trailer or for towing cars, anything thats magnetic. They are factory wired so no crossed wires or grounding problems. They come from Northern Tool or Harbor Freight and cost about $40.00 on sale which is often.