Running lights not working on my four flat trailer lights

[16' of therapy]

Ever since I bought my boat and trailer four years ago when I turn on my headlights the trailer running lights don't come on. Breaks, turn signals, and four ways all work fine. I have a four flat hook up. Each tail light has two wires and a ground witch are all ran up and have good connection, also all grounded out at the coupler as it's suppossed to be. Is it the lights themselves that just don't have that capability? I'm lost, thanks for any help!

 

[jtexas]

Re: Running lights not working on my four flat trailer lights

you been running 4 years with no taillights?

when you say "grounded at the coupler" what's that mean, exactly?

take that white ground wire from the trailer connector, strip about 4 inches of insulation, and wrap it around a bolt on the trailer frame. wrap it good, then tighten it down, I mean tight.

I assume you've checked the vehicle connector for voltage on the brown wire?

 

[16' of therapy]

Re: Running lights not working on my four flat trailer lights

No I've been driving for four years without "running" lights. I have taillights. I don't drive at night so it's realy not an issue. But if I do huh they don't work. Like if I turn on my headlights the trailer lights don't come on. And yes, at the coupler (front of trailer) it is grounded, and grounded properaly.

 

[Bondo]

Re: Running lights not working on my four flat trailer lights

Ayuh,... Get a Test Light,+ See why they're not getting Power...

 

[Silvertip]

Re: Running lights not working on my four flat trailer lights

The marker (running) lights run off the same brown wire that feeds the tail lights. If this is a relatively new trailer, check inside the trailer tongue. Very often their is a bunch of bullet connectors on the harness tucked in their. The feed to the markers may simply be disconnected. Don't spend a lot of time looking at the lights themselves as it is a "feed" problem to those four lights.

 

[jtexas]

Re: Running lights not working on my four flat trailer lights

oh, those running lights, yeah mine have never worked either. Some prior owner disconnected 'em.

 

[Shizzy]

Re: Running lights not working on my four flat trailer lights

what kind of vehicle are we talking about?

do the running lights work on any other trailers you have pulled?

does your vehicle have a seperate tow/haul fuse?

I had the same issue with my 03 Ranger and it turned out there was a seperate tow/haul fuse under the hood.

 

[Dkrager]

Re: Running lights not working on my four flat trailer lights

First thing I do when buying a trailer.... Get rid of the 4 prong flat plug, they are junk. (Even though that might not be your problem), I switch all my trailers over to the new 7 pin rv style plug found on every vehicle now.

Check for those scotch locks (inline wire taps). My brand new pontoon trailer that I paid good money for, has those cheap *** scotch lock for all the marker lights.(I wasn't very happy to find them) I'm sure eventually they will fail.

 

[16' of therapy]

Re: Running lights not working on my four flat trailer lights

Thanks everyone for your help so far. I will check out the brown wire connection and see if anything is not in order there. I have an F150 and no haven't ever pulled anything else to notice if it's my truck that has something wrong and not the trailer. Electrical work sucks for someone who doesn't do it. But it's better than paying a marina a thousand bucks to do it.

 

[jtexas]

Re: Running lights not working on my four flat trailer lights

Nah, if your taillights are on, the brown wire is fine. The ground is fine. The truck is fine, too. It's all in the trailer. Specifically, it's all in those marker light fixtures.

 

[Dkrager]

Re: Running lights not working on my four flat trailer lights

I'd say if you have tail lights, but no side marker lights, there has to be a problem on the trailer. Most times they tap the main wire with scotch locks to run a wire to the other marker lights. After getting wet numerous time the connection can get corroded and fail. Here's a pic of what I'm talking about.

 

[raven7]

Re: Running lights not working on my four flat trailer lights

My F150 has a seperate fuse panel for the flat 4 / 7 pin trailer plug. It's located behind the right side kick panel in front of the passenger seat. Just incase you need to backtrack anything.

 

[HHIBouy]

Re: Running lights not working on my four flat trailer lights

Ever since I bought my boat and trailer four years ago when I turn on my headlights the trailer running lights don't come on. Breaks, turn signals, and four ways all work fine. I have a four flat hook up. Each tail light has two wires and a ground witch are all ran up and have good connection, also all grounded out at the coupler as it's suppossed to be. Is it the lights themselves that just don't have that capability? I'm lost, thanks for any help!

After re-reading your post, it seems you are saying that none of the running lights on the trailer have been working including the ones that also serve as brake/turn on the rear of the trailer, only in a dimmer mode. If this is the case, you have an issue with the brown wire that could start in the truck all the way back thru the trailer. If so get a test light make sure the light has a good ground, and start at the connector checking for power. if it has power on the brown wire at the truck side, then the problem is in the connector on the trailer or back thru the trailer wiring it's self. just keep probing the wiring until you find no power as you move towards the rear of the trailer. I just finsh repairing my trailer running lights and it was as simple as a corroded pin in the connector.

 

[Raptorman]

Re: Running lights not working on my four flat trailer lights

I had the same problem. I had directionals and brake lights but no running lights. After fooling around with the trailer for a hole day I found out there
were seperate fuses for my running lights and directionals for the trailer plug.
I have a GMC Envoy. The fuse for the directionals was under the hood and the fuse for the running lights was under the back seat on the driver's side.
Not shure if this is your problem but I would check at the plug on by truck first.

Raptorman

 

[jtexas]

Re: Running lights not working on my four flat trailer lights

After re-reading your post, it seems you are saying that none of the running lights on the trailer have been working including the ones that also serve as brake/turn on the rear of the trailer, only in a dimmer mode. If this is the case, you have an issue with the brown wire ...

clarified in a subsequent post:

No I've been driving for four years without "running" lights. I have taillights. I don't drive at night so it's realy not an issue. But if I do huh they don't work. Like if I turn on my headlights the trailer lights don't come on. And yes, at the coupler (front of trailer) it is grounded, and grounded properaly.

btw, if brake/turn aren't working, your problem is in the green and yellow wires not the brown. What does "dimmer mode" mean?

 

[HHIBouy]

Re: Running lights not working on my four flat trailer lights

Dimmer mode

To omit less than the brightest amount of light.

Not as bright as when your turn or brake lamps are working.

Yeah I know he said he had tail lights but he may have been referring to the brake/turn lamps, as he then stated he does not drive at night. I have found that we sometimes read things into what other have stated, but it's really not what the mean.

 

[jtexas]

Re: Running lights not working on my four flat trailer lights

LOL, dimmer = "more dim", duh, I was headed in a different direction entirely........

 

[burp]

Re: Running lights not working on my four flat trailer lights

Ford trucks have a power distribution box under the hood, right in front of the driver. A 20 amp fuse inside the power distribution box provides power for the trailer marker lights. Neighbor had an Expedition and an F150, both had the blown fuse problem as the trailer marker lights were shorted to the frame.

 

[KermieB]

Re: Running lights not working on my four flat trailer lights

I know this may be very elementary, but have you checked the bulbs? When trouble shooting.... check the simplest things first.

 

[16' of therapy]

Re: Running lights not working on my four flat trailer lights

LOL Oh my word, yes I have brake, turns, and four ways all running. Just when I turn on my headlights the taillights don't work. I will check my fuses and hopefully find were there at. Thanks for everyones help so far.