Trailer Lighting

[davidh50]

I recently purchased a small fishing boat and the trailer lights were fine last week. I hooked it up to go fishing yesterday morning and nothing! I have one brake light and turn signal on the passenger side. No running lights at all. I've checked the pigtail on my truck with a voltmeter and all is fine there...full voltage on all terminals. When I connect the two pigtails, I've even left a gap between them, but still hooked up and put the voltmeter to it and it doesn't read anything but the one brake and turn signal. I'm no electrician, but I know enough about this sort of thing to know that something crazy is going on! To beat it all, I just sold another boat and it did the same thing this morning when I hooked it up! Any help would be greatly appreciated!!

In the dark...
David

 

[timheis]

Re: Trailer Lighting

Do you have a conventional 4-wire connector?

If so, with the connectors unplugged, using an ohmeter, check the resistance of the trailer connector, yellow wire to ground and the brown wire to ground. Over time some strands of the wire may be in contact with the trailer. Take the lamps out first so you should read a totally open circuit. with the lamps out, you should read infinate(totally open circuit). If the meter deflects at all, you have a short. The yellow is the left stop/turn and the brown is the running lights.

 

[davidh50]

Re: Trailer Lighting

Yes, I have the 4-wire connector. I just tried what you said and not being that versed in reading the ohms, I assume what you mean by "open circuit" is that the meter doesn't respond when you follow the procedure you described? If so, that's what I've got....an open circuit. Red lead to brown wire, black lead to the trailer. Red lead to the yellow wire, black lead to trailer...nothing.

Thanks,
David

 

[davidh50]

Re: Trailer Lighting

Okay, I've traced the wires from front to back and back again and I find no "open" wiring in the harness. Now what do I do? Things like this drive me bonkers!!!

David

 

[Silvertip]

Re: Trailer Lighting

Obviously if the connector on the tow vehicle is corroded and a sloppy fit, those electrons won't go anywhere. If that's ok, make sure the ground wire (normally white) in the trailer harness is grounded to the trailer chassis and that the connection is clean and tight. Don't just look at it. Disassemble and clean it. Then make sure all of the other trailer light housing mounting bolts/screws are making good connection to the trailer frame. That's how each of the lamps get their ground. Now using an ohm meter, measure from the white wire in the trailer plug to the trailer frame. You should show continuity. If you have a battery charger, connect the negative lead to the trailer frame or the ground pin on the connector. Touch each of the other three terminals on the plug. The corresponding light should come on. If not, use a pin to poke into the wire at various points to find where voltage is and where it isn't. Also make sure the tail light bulbs are not inserted 180 degrees wrong. Yes -- they are keyed but the sockets are made so blasted cheap people continually force the bulbs in the wrong way.

 

[davidh50]

Re: Trailer Lighting

Thanks for the advice! I did what you said yesterday and found out it wasn't the trailer at all! I took a battery and ran test leads from it to each wire on the trailer and everything worked like its suppose to. I knew then the problem was in my pigtail on the truck. Come to find out, this "custom" trailer plug I had installed at a boat center here in town had corroded connectors inside it. I used a small fine tooth file to remove the corrosion, but I still wound up with intermittent power. One minute it would work, the next it wouldn't. I can't stand that! So, I just cut the darn thing off and rewired the pigtail straight to the trailer wiring harness. Everything works perfectly now! Thanks for the help from each one that responded. Hope God richly blesses each and everyone of you. Happy fishing and boating!!

David