wiring help

weightset

Seaman Apprentice
Joined
Sep 12, 2012
Messages
33
im ussaully decent at wiring till i got this older boat trailer which the wires coming out of the lights are brown and white on one side and the other is red and brown what wires do what lol thanks for any help btw its on a normal 4 pin harness. Is it the brown being running lights and the white and red being turn signals
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,413
Re: wiring help

im ussaully decent at wiring till i got this older boat trailer which the wires coming out of the lights are brown and white on one side and the other is red and brown what wires do what lol thanks for any help btw its on a normal 4 pin harness. Is it the brown being running lights and the white and red being turn signals

Ayuh,... Probably, but just put power to either 1, 'n see which is Brighter...
 

batman99

Petty Officer 1st Class
Joined
Sep 13, 2012
Messages
393
Re: wiring help

I agree.

Lift hood of your 12V vehicle, take 12" short 12V - 12 guage wire and "test away" - on the vehicle's 12V battery. Based on your wire colors, I'd also assume your trailer lights are self grounding. If so, take light assemblies steel bolt and run short wire to 12V "-" post. Then, take short wire on 12V "+" post and touch one of the trailers lights color wires. If possible, use a 12V probe test light between battery and test wire as well. The brigher light is the brake wire. The dimmer light is the clearance (aka: night time) lights. This testing works for me....
 

kgrezlik

Cadet
Joined
Jan 5, 2002
Messages
7
Re: wiring help

Need some help-

Towing my 18 ft Fisher bass boat with my Chevy Silver 1500 over the summer, I noticed my trailer lights were funky- I had good turn signals, brake lights, emergency flashers, but no running lights- trailer was dark if I wasn't turning or braking. I thought it was the trailer, but a week later I borrowed a friends boat, 19ft Avalanche, and had the same issue- all trailer lights dark unless I was braking- I checked every fuse in the fuse box on my truck and all are good- any advice?
 

briangcc

Commander
Joined
Jul 10, 2012
Messages
2,429
Re: wiring help

kgrezlik,

You really should split this off to your own topic instead of hijacking someone else's post.:cool:

In any event, since your tow vehicle is the only constant in the equation, I'd look seriously at the wiring for your truck. You can get a plug in tester for your wiring that lights up the LED's on it when you activate the appropriate circuit - lights, brakes, etc.

I'd also suggest checking the plug on your truck along with the adapter you're using - since your truck is more than likely a 7 pin and I'm guessing your trailer is a 4 pin so an adapter is probably being used.

Good luck.
 

Georgesalmon

Lieutenant Commander
Joined
Apr 14, 2012
Messages
1,793
Re: wiring help

Be sure you check the grounds. I've seen all kinds of wierd problems with trailer lights that were cause by bad, weak, intermittent grounds.
 

sccatfish

Petty Officer 2nd Class
Joined
May 29, 2009
Messages
147
Re: wiring help

Need some help-

Towing my 18 ft Fisher bass boat with my Chevy Silver 1500 over the summer, I noticed my trailer lights were funky- I had good turn signals, brake lights, emergency flashers, but no running lights- trailer was dark if I wasn't turning or braking. I thought it was the trailer, but a week later I borrowed a friends boat, 19ft Avalanche, and had the same issue- all trailer lights dark unless I was braking- I checked every fuse in the fuse box on my truck and all are good- any advice?

I've heard that the fuses for the trailer lights are sometimes in a second fuse box in some trucks. If there aren't any fuses in the box you looked in that are labeled for the trailer I'd look for a second box and look in the owner's manual.

But first, I'd check the business end with a test light or volt meter. Make sure you're not getting power at the plug. It's probably either a fuse, a bad connection, or your 7 to 4 adapter isn't making good contact.

If your truck doesn't have a factory tow harness then I'd check the connections where the wires are tapped into the truck's wires. Usually all that is used are those crappy quick connects that you fold over, which can cause serious corrosion issues.
 

kgrezlik

Cadet
Joined
Jan 5, 2002
Messages
7
Re: wiring help

I've heard that the fuses for the trailer lights are sometimes in a second fuse box in some trucks. If there aren't any fuses in the box you looked in that are labeled for the trailer I'd look for a second box and look in the owner's manual.

But first, I'd check the business end with a test light or volt meter. Make sure you're not getting power at the plug. It's probably either a fuse, a bad connection, or your 7 to 4 adapter isn't making good contact.

If your truck doesn't have a factory tow harness then I'd check the connections where the wires are tapped into the truck's wires. Usually all that is used are those crappy quick connects that you fold over, which can cause serious corrosion issues.

Thanks all for the help-
 

okbayliner

Seaman Apprentice
Joined
Jul 26, 2011
Messages
30
Re: wiring help

look in fuse box under the Hood that is where it is on my truck beside battery
 

MH Hawker

Vice Admiral
Joined
Jul 13, 2011
Messages
5,516
Re: wiring help

This may help. click on the picture to make it bigger.


trailer%20wiring%20diagram.jpg
 

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
Re: wiring help

The brown wire usually goes to the running lights. If you don't have any power to this wire coming from the truck sometimes the truck's owners manual will show where all of the fuses and relays are located. On my truck I have had to change a relay in the box under the hood before. I tow RVs as well as boats so I keep spare relays as well as fuses.
 
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