trailer brake light blinkers not working?

[sailors hornpipe]

ok today about 8 pm as it was getting dusk i backed up my truck (2009 ford f 150 with 7269 mi) and hooked up my trailer lights in the drive way to check them - ive had the boat out once for a maintenance run (1992 180 nitro fs /150 hp johnston evinrude 17.5 ft) i purchased the bost a month ago and am trying to get it ready for the season-now with the lights hooked up all the trailer lights light up including the brake lights but the problem is the brake lights do not brighten( to signal actual braking) when the i step on the truck brake pedal - i did notice that the drivers side trailer brake light brightens ever so slightly but almost unnoticeable unless you are looking really hard at a couple of feet away- also the blinkers do not work on the trailer but the brake lights are functioning and stay lit - from reading other threads on this subject i checked to see if the trailer brake lights were grounded and they are ,i can see the ground wire screwed into the frame of the trailer on each side- i read my trucks fuse and relay info and only saw one fuse in the whole fuse box having to do with trailer lighting it was marked (trailer brakes) however upon inspection the fuse was good - i did see in the truck manual that there are relays that are marked ( right trailer turn signal) and ( left trailer turn signal) but unless im wrong i dont think a relay would go bad on a 6 mo old truck, and isnt the fuse suppose to blow before the relay is damaged anyway? im guessing it has some thing to do with with bulbs inside the the trailer brake lights themselves? or could it be the trailer connection plug that connects to the truck? i also checked all visible wiring for exposed / stripped areas- oh and yes blinkers and brake lights on the truck work fine- i did see two wires hanging down with metal connectors on them wrapped around the frame of trailer/ drivers side brake light side - these two wires are brown and white and are not long enough if unravelled to reach the passengers side trailer brake light - dont know if those two wires have something to do with it? please please help / im stumped!

 

[sqbtr]

Re: trailer brake light blinkers not working?

Did you check the fuse box under the hood?

 

[Timmy222]

Re: trailer brake light blinkers not working?

sounds like it is not getting a good ground. Pull the ground wire off and make sure they are clean and making good contact with the trailer. Put them back on tight enough and try the lights again. Let us know what happens.

 

[dockwrecker]

Re: trailer brake light blinkers not working?

Brown wire is running lights, white wire should be a ground.

 

[bitterboater]

Re: trailer brake light blinkers not working?

I am having a similar issue with my Sub. I have narrowed it down to possibly the trailer plug itself.
Having tested the wires before, at and immediately after the wire plugs at the truck trailer connection.
Using my test light I have power to the Tail\Brake light wire (Brown wire) as well as the Right turn wire.
However I do not have power to the left turn wire.

It is possible that you have a similar issue. Try testing the wires at the plug.

 

[sailors hornpipe]

Re: trailer brake light blinkers not working?

ok so i checked the plug coming from my truck with a tester light and found there was no power to the blinkers of the trailer so i checked as one of you mentioned the fuse box under the hood and tracked down a blown fuse having to do with trailer light turn signals and i replaced the fuse - now the the right trailer light brightens when i mash the brake pedal and also the blinker works on the right side now but the left side does not brighten when i press the brake pedal and the left side blinker does not work but the left side brake light is on- i tried looking really hard at the light to see how many bulbs are in there -are there one or two bulbs in each trailer brake light? i think through the lens i see 2 bulbs in the now working right side trailer brake light but hard to tell with the glare so could it be a bulb? the brake light doesnt go on and off by itself just sitting there so i suppose it is not a grounding issue - also i ckecked the trucks plug again after replacing the fuse and all power including blinker pulse power is there to both sides so its not the tow vehicle so im guessig a bulb? so again are there 1 or 2 bulbs in each brake light? and is it possible that if there are 2 bulbs -1 maybe out? any ideas guys?

 

[sqbtr]

Re: trailer brake light blinkers not working?

It's a single bulb with two functions, pick up an 1157 bulb and you should be good to go, unless it's one of those waterproof housings.

 

[BamaGunner]

Re: trailer brake light blinkers not working?

did you find out where those 2 wires on the left side (drivers side), that were wrapped around the trailer went to? Check around the lens itself. You see a ground wire at the tongue of the trailer, there could be a ground wire coming out of the lens. Some of the sealed units though, have the ground hooked to the studs internally that mount the lens to the trailer, so the lens grounds to the metal its attached to. Could possibly have a grounding issue there. I will say this, it is something simple. I work for the town here, and we have an 07 F-250 that I was having the same problem with. I came to find that the factory plug on the truck side, didnt like the new wiring harness when I rewired a trailer. The ground liked to stay a little loose in the socket, and it was having to ground through the ball, which at times, it still doesnt like to work, but wiggling it around a little bit or taking a couple corners, and it starts working again. Good luck.