Trailer lights not working when hooked up to my truck

Discussion in 'Boating' started by JPritch, Apr 20, 2007.

  1. JPritch

    JPritch New Member

    Messages:
    1,852
    State:
    Lynchburg, VA
    I am having trouble getting the trailer lights to work via my truck. The trailer is brand new, fine and working (was hooked up to the delivery guy's truck and all was ok).

    The wire harness extension from my truck was really old, so I replaced it yesterday, but it's still not working. That lead wire harness connects into a type of t-connector, which also connects what I imagine are each of the taillights. The taillights and brakelight for my truck work fine.

    Any possible diagnosis? Do I just need to replace the connector, or could the problem run further up the chain?

    It's a '95 F-150 with a 4-wire harness if that helps at all.
     
  2. BAM

    BAM New Member

    Messages:
    827
    State:
    Tennessee
    First thing to do is get a volt meter or test light and check the plug on the truck, Each pin. Check the ground also, should be the white wire, that causes more problems than anything. Brown wire is tail lights, Green wire is right turn, Yellow wire is left turn, and White wire is ground. Brake lights run off of the yellow and green.
     

  3. JPritch

    JPritch New Member

    Messages:
    1,852
    State:
    Lynchburg, VA
    Thanks. Off to U-Haul at lunch, they have a 4-wire tester for around $4.
     
  4. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Sounds as though you have a snake in your wiring system. LOL. I would think the problems more in your connector - you did say it was old. For about $10.00 you can get new wire and it probably would save you more time in the future to replace the wiring now. You may, if not all ready, want to raise the tail lights so they are never submersed in the water when the trailer is in. You can do this by rigging them on PVC pipe, or by getting some angle iron, a hack saw and a drill and fabricate a support system. I am not sure about a '95 truck, but my 2004 required a converter to connect the tail/stop lights to a 4 wire harness. Why they always have to change something I'll never know.
     
  5. broncstomper

    broncstomper New Member

    Messages:
    13
    State:
    ga
    also, there is a fuse under the hood that is just for trailer hookup(If the truck had a factory towing package). I always start with checking the fuses and more times than not that'll be it. also make sure your trailer is grounded to the truck.
     
  6. porboy

    porboy New Member

    Messages:
    629
    State:
    TX Panhand
    If this is a tilt trailer you need to run a ground wire back where it tilts to make a good ground. Just drill a hole in each part of the trailer near the place where it tilts and screw a conection wire to both places. You will have to leave a little slack so it will tilt without tearing the wire loose. Be sure to grind the paint off to make a good conection.
    Spent two days replacing everything before I figured it out. This may be or not be your problem.
    Bill
     
  7. jlingle

    jlingle New Member

    Messages:
    1,036
    State:
    Altus, Okl
    I hate trailer lights, and for some reason they always reciprocate the feelings. The running lights refuse to work on my boat. I've unhooked, rehooked, cursed, thrown things, replaced both lights, checked fuses, etc. Now I just use my boat during the day.:lol:

    Pat McManus said that Man invented the wheel, then he invented the trailer, and every since then he's been trying to figure out trailer lights.

    Sorry, I couldn't be much more help. I think working on trailer lights requires at least a 5 gallon bucket of curse words. You may check, but this has been my experience.
     
  8. JPritch

    JPritch New Member

    Messages:
    1,852
    State:
    Lynchburg, VA
    Fixed it!

    Went to Uhaul and bought a 4-wire tester and a t-connector for my Ford truck model year. Decided to test my existing setup first and nothing lit up on the tester. So I took out the old t-connector and installed the new one, and what do you know...it works, at least on the tester. Will have more time tonight to hook it up to the trailer and see if it 100% works.

    I just had the boat delivered Tuesday, but haven't even been able to take it out for driving/backing up practice because I'm not legal with the inoperable lights.

    Thanks for the help everyone.
     
  9. whitewhiskers

    whitewhiskers New Member

    Messages:
    764
    State:
    Evansville, Ind
    Josh, i have a 92 F150. it had the same poblum. sorry i'm late, at least it wasent farther up the harness and a real bear to find, also the rasing of lights is a great idea it'll save a lotta headaches latter. :crazy:
     
  10. riddleofsteel

    riddleofsteel New Member

    Messages:
    353
    State:
    NC
    Mine would not work either until I hooked the trailer ground wire to the frame of the trailer. Be sure it is making good metal contact if the trailer is painted.
     
  11. Katmandeux

    Katmandeux New Member

    Messages:
    1,618
    State:
    Checotah, Oklahoma
    Jerrod nailed it.

    Look, after you do all of this, and spend all of this money, they're gonna quit you some night, anyway, and you may not even realize it.

    Plan for this, and put a pair of reflectors on the back of the trailer, so people will know there's something back there. A little dab of reflective tape on your transom isn't a bad idea, either.
     
  12. badkarma

    badkarma New Member

    Messages:
    772
    State:
    Oxford,Miss
    Hey if you do what I did you won't have to worry about getting your trailer lights wet.I put simitruck trailer lights on my boat trailer,they're sealed,glued tight and water will not hurt them.The only problem is if a blub blows you can't just replace it cause it's sealed you have to change out the whole light.It's not to bad because I've had them on my trailer for 5 years and only had to change out 1.
     
  13. JAYNC

    JAYNC Active Member

    Messages:
    1,312
    State:
    Newport N.C.
    When I bought my boat everything worked fine as far as lighting went, then after a while I noticed that the trailer lights would flicker all the time while trailering. I then realized that the ball was getting rusty, I bought a new ball and started using the hitch ball grease, I haven't had a flicker for almost two years now. Make sure you get a new ball and use the grease, sounds like a simple ground problem. Also in the trailer section at walmart or anywhere that sells hitches they sell trailer harness lights testers, they plug right into your harness and tell you immediately if your harness is good or bad, they are only a few dollars and will save you lots of head aches.
     
  14. JPritch

    JPritch New Member

    Messages:
    1,852
    State:
    Lynchburg, VA
    I had the chance to hook my truck up to the trailer last night and the lights worked perfectly! No fast flickering or anything, nice and steady.

    I like the idea of putting the lights up high so they're out of the water. When I get some guides, I think I will run the wires up them and mount the lights on top of the guides.
     
  15. daniel-delarosa

    daniel-delarosa New Member

    Messages:
    392
    State:
    seminole, oklahoma
    I haven't had a problem with trailer lights in years. Boat trailer, car hauler, stock trailer or travel trailer, not one problem. I read this post yesterday morning, after work I hooked up the boat headed to the lake for a little R and R. I got back to the dock after dark. As I was backing down the ramp I noticed I didn't have any lights! Talk about a bummer.
     
  16. JPritch

    JPritch New Member

    Messages:
    1,852
    State:
    Lynchburg, VA
    Sorry to jinx you bro! :lol:

    Seriously, I hope you can get everything ironed out ASAP.
     
  17. blkhawkdwn

    blkhawkdwn New Member

    Messages:
    169
    State:
    Clarksville, Tennessee
    i had the same problem with my trailer. it would work on my partners truck but not mine. the end result was i took the T-box thingma jig off and connected the wires straight to the plug that connects to the trailers plug and now the lights work fine with no problems at all.
     
  18. SubnetZero

    SubnetZero New Member

    Messages:
    1,619
    State:
    Sherman IL
    Harness on my Truck started acting up.. Left side worked fine, Running lights good.. But no Right Turn signal or Brake light.. So tonite I broke out the multi-meter and started checking pins.. Figured out the green wire was dead in the pigtail.. Mmm, tore apart the harness underneath the truck to check the wire before the pigtail... Still nothing... Did a continuity check, passed with flying color.. Stumped.. must be farther up the harness (GAH!!!) ..hmm, just for giggles let me look over the fuse panel... Don't see how it could be the fuse with half of the lights working, and all of em work with running lights... WHAT!! Ford in their wisdom has a seperate fuse FOR EACH Side of the pigtail, and JUST the pigtail... BINGO.. blown fuse for the right side of the towing pigtail :embarassed:

    2 hours of unwrapping, checking wires, and rewrapping, turned out to be a 2 minute fuse swap..

    So, I agree, Check the fuses first Thing, Always :confused2:
     
  19. thunderchicken

    thunderchicken New Member

    Messages:
    769
    State:
    Yuma Az
    A lot of problems with lights not working or working intermittantly or flickering is caused by a bad ground. Paint, rust, dirt, corrosion, etc. will interfere with a good ground. Fuses and ground problems can make ya have a bad day. One time I was in a hurry to get to the lake to catch a big fish that was waiting for me and the trailer lights would not work to save my life. I walked around the trailer, had someone in the truck hitting the brake and turning the turn signals on.......nothing. It was giving me a headache. After a lot of thought it came to me..and waa laa, they were working!!! It also helps if you plug the connector in! :lol:
     
  20. JAYNC

    JAYNC Active Member

    Messages:
    1,312
    State:
    Newport N.C.
    Just remember that the trialer grounds itself to the truck through the hitch, if you dont have a clean and well greased trailer coupler, hitch ball, and receiver you will never have a good ground. When your buying trailer lights, dont buy the kind that just say submersible, buy the kind that say water proof. The submersible ones can get water inside them, the waterproof ones dont, they have seals and the good ones dont leak. When replacing and lights make sure that all your connections are soldered and heat shrinked and then sealed with sealant. The more effort you put into wiring the longer it will last.