Stupid 12v trailer wiring!

Reply

  #1  
Old 09-25-19, 05:51 PM
XSleeper's Avatar
Group Moderator
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 23,320
Received 216 Votes on 201 Posts
Stupid 12v trailer wiring!

Ok, so I've got this small 5x8 lawn trailer and the tail lights didn't work at all. So I got new lights, cleaned off the frame with a grinder (since these lights use the frame where they mount for a ground) hooked them up temporarily, and everything worked perfectly.

A few hours later I wanted to finish the job by soldering the wires together then was going to slide waterproof shrink tube over them. Unfortunately I'm color blind and somehow mixed up the left tail light wires. Discovered this when I tested and nothing worked.

So I switched the wires back the way everything should be, but still no love. In retrospect, I probably should not have had the trailer hooked up and hazards on while I did this. But to my knowledge, no hot wires ever touched a ground. But I guess I was soldering them with an electric soldering iron, so I suppose that is what grounded it.

The correct voltage is present at the connector on my truck but there is no power at ANY of the tail light wires. I can't find a fuse anywhere on the harness but there must be one concealed inside the frame a few feet behind the hitch. Is that a reasonable conclusion?
 
Sponsored Links
  #2  
Old 09-25-19, 06:54 PM
XSleeper's Avatar
Group Moderator
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 23,320
Received 216 Votes on 201 Posts
New info... just performed a continuity test... all my power wires are going to ground. What the heck???
 
  #3  
Old 09-25-19, 07:00 PM
Member
Join Date: Jan 2013
Location: U.S.A.
Posts: 2,049
Received 60 Votes on 55 Posts
Based on my experience, maybe not vast, but enough, I would say that it is pretty rare to find a fuse on a trailer of that size. Several things come to mind, but with nothing working on the trailer I would be back to chasing the ground, starting with the connector on the truck. If it's factory installed, and the truck is in decent shape, not a lot of rust and corrosion, I would be content at least for the time being if the ground checked out good at the connector. The way I would check it to be sure is with the cable disconnected at the positive battery terminal and a long wire from the negative terminal to the connector. Pain in the but, I know, but then I'd probably check continuity from the trailer connector to the tail lights. If it's an older trailer, it quite likely uses 1157 bulbs, and unless you've already been there and/or have maintained it yourself for a long time, another place you might want to start is pull those bulbs out and make sure that they are oriented correctly. I can't remember all of the problems, but do remember tracking a few anyway back to the bulbs having been forced in the wrong way. And if the wiring is old, any more I would probably just rip out the old and replace it. I pulled out a roll of trailer harness wire off a bottom shelf in the shop a couple of years ago to cut a piece off for a neighbor, and it was Packard brand which was good quality in its' day, and the exposed ends were bright shiny copper, but when I cut it the wire was all black. So after cutting something newer and he was on his way I stripped that roll back in several spots and darned if it wasn't black every place I checked. Connected a meter to each end and had nothing. So it does break down, and maybe the little incident of cross connecting it was enough to take out an already bad spot.
 
  #4  
Old 09-25-19, 07:02 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,965
Received 59 Votes on 52 Posts
You will read continuity to ground if the lights are incandescent as you will read through the filament.

Make sure you have a wire going to the frame of the trailer off the connector to the truck. Do not rely on just the ball.

I have never seen a fuse on a simple trailer.
 
  #5  
Old 09-25-19, 07:21 PM
XSleeper's Avatar
Group Moderator
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 23,320
Received 216 Votes on 201 Posts
Ok, good advice, thank you. So am I correct in thinking that if I wanted to test the continuity of each wire from the plug to the tail lights, all I would have to do is take all the bulbs out?
 
  #6  
Old 09-25-19, 07:31 PM
Member
Join Date: Jan 2013
Location: U.S.A.
Posts: 2,049
Received 60 Votes on 55 Posts
Correct, that is how I would do it. Not knowing what you have for a plug, unless it's molded you might want to open it up and see what you have in there too. Could be as simple as a loose or corroded terminal inside the plug.
 
  #7  
Old 09-25-19, 07:55 PM
XSleeper's Avatar
Group Moderator
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 23,320
Received 216 Votes on 201 Posts
Yeah its a molded 4 prong connector. (Ford F150) Okay, no fuse. Good.

Ok, so good news. Everything is working again. I double checked the trailer ground. (Should probably scuff that up better) Removed all the bulbs, cut off the running lights which were smashed, checked the continuity of each wire from the molded plug to the tail lights, everything checked out ok. So then I hooked it up to the truck again and it works!

I don't know if it was an intermittent ground or if the running lights were short circuiting everything. I will probably replace them next (so that they can get smashed again next time I go down a gravel road.) Trailer lights are such a pain in the you know what.

Thanks for the help!

I'll probably try soldering again this weekend if I have time.
 
  #8  
Old 09-26-19, 04:06 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,965
Received 59 Votes on 52 Posts
Trailer lights are such a pain in the you know what
True that! That and batteries and tires.
 
  #9  
Old 09-26-19, 05:23 PM
Member
Join Date: Jan 2013
Location: U.S.A.
Posts: 2,049
Received 60 Votes on 55 Posts
This was about 40 years ago so the statute of limitations has run out, we were going to take the snowmobiles up north the next weekend, it was the dead of winter, colder than heck, the days were short, I was working full time and going to college at night, and the doggone trailer lights didn't work. Can't remember the particulars, although that may have been when I started running separate ground wires to each light, but I got them working and life was good. Only problem was that I couldn't resist the urge to tow it down the road a mile or so and make sure everything stayed working. Yup, you go it, I had just set the coupler on the ball to work on the wiring, hadn't clamped it down, and, as if planned that way, the trailer came uncoupled at the first ravine, and the plug held but all of the wires on the trailer pulled out of it. Overall, again, can't remember all of the particulars, I think I had the wires back in the plug withing 15-20 minutes, so no big loss there, but between going back for a come-a-long, winching the trailer back up to the road, and the embarrassment of doing something so stupid I recall it well enough to ensure that I always double and triple check everything before heading out the driveway.
 
  #10  
Old 09-26-19, 06:32 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,965
Received 59 Votes on 52 Posts
Not nearly that long ago I loaded up a snowmobile and brought it over to a buddies house to transfer it to his trailer for an ice fishing trip. When I got there to unload I realized I didn't put on the ski bar to secure the snowmobile to the trailer. Then, when I went to the front to pull the pin on the bed I realized I didn't do the coupler either! Wow! I felt dumb and very lucky all at once! I also double and triple check things now.
 
  #11  
Old 09-27-19, 04:58 AM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 7,461
Received 72 Votes on 67 Posts
Wow! I felt dumb and very lucky all at once! I also double and triple check things now.
Hearing you say this makes feel a bit better when I've done a few stupid things.

Recently I hooked up my trailer to the car and thought the ball was properly locked into the hitch. Proceeded to drive the riding mower onto trailer. Talk about flipping the front end up. Glad only a only few people saw it. I was so embarrassed. Did similar with the big trailer a couple year ago, Just totally forgot to attach trailer to car before driving the ATV on to the trailer. Now I always double check also.
 
  #12  
Old 09-27-19, 05:11 AM
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 46,164
Received 131 Votes on 117 Posts
I was having trouble with the hitch on my old tandem axle trailer so I had it in front of the barn working on it. I took it all apart and reassembled it thinking I had it fixed, hooked up to my truck, let out the clutch and it just popped off the ball [and I hadn't hooked up the chains] The runaway trailer was stopped by my son's old 4x4. Fortunately he didn't care about the body! I replaced the hitch coupler and vowed to never forget the chains even if I'm only going a short distance on my property.
 
  #13  
Old 09-27-19, 08:19 AM
Member
Join Date: Jan 2012
Location: Canada
Posts: 2,739
Received 15 Votes on 15 Posts
Tolyn Ironhand,
I did the same thing with my dad's double snowmobile trailer when hauling my broken down motorcycle.
Did all the prep work on the 2x4 wheel chocks (~650lb wet weight 1979 gs750), strapped it down, forgot to install the tilt pin.
Nearly tore the top deck off the trailer when the trailer tilted.
 
  #14  
Old 09-27-19, 08:55 AM
Member
Join Date: Jun 2002
Location: Northern Minnesota
Posts: 1,624
Received 1 Vote on 1 Post
My son finally came for his old boat and trailer from my yard, needed new lights. Told him to leave the original wires, we'll use them for grounds right to the plug.

Much better me thinks.
 
  #15  
Old 09-29-19, 01:23 PM
XSleeper's Avatar
Group Moderator
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 23,320
Received 216 Votes on 201 Posts
Long story short, I got all new tail lights, all new marker lights, and now everything works great. Soldered all the connections, covered the splices with heat shrink tube. Sanded down to bare metal where the ground wire and tail light posts connect to the frame, everything works good now.

We have a lot of liquid salt used on our roads in winter months and its pretty hard on a trailer in tow. Seems trailer lights don't last long on gravel roads either. But I should be good for another couple years.

Next time I have trouble I think I will have to replace the whole wiring harness. There were indications that the wire was starting to turn black with oxidation inside, like aka pedro mentioned earlier. Those areas were harder to solder.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: