View Full Version : Electrical Illiteracy & Trailer Wiring

Evan Showell
12-10-2001, 05:48 AM
I confess! I am astoundingly ignorant about things electrical. I marvel every time I throw a light switch and the room brightens. Amps are things I see at rock concerts. I do a cuircuit in the weight room and grounded -- well, I haven't been that bad in a while.

The problem -- being male, the world assumes I am genetically programmed with an innate understanding of electricity. Accordingly, directions for things such as wiring a small boat trailer are seemingly unavailable.

I have such a trailer. I need to wire it. The tow vehicle is a 1986 Volvo 240 wagon. I have something called a tail light converter and four prong wiring, white, green, red and brown. The kid at the local trailer place hand wrote a chart indicating which wires work for which lights on the trailer. Having been overcharged for new wheels, I do not want to go back there to have them wire the connection to the car. I also do not want to pay my local mechanic to do same. (You could say I'm cheap, but that would be only a part of the story -- don't want to hear SWMBO -- "I knew it would cost more than you figured to get things ready." The lights on the trailer have been tested and work. The trailer was free (for the cost of disposing of the fiberglass wreck of a Jet 14 that came on it [$0.04/lb.]) I've got to believe this isn't rocket science. I've looked for printed instructions and found none.

Anybody got any basic advice about where to look for printed info, or how to go about this?

For the curious, the boat to be towed is a cold molded Jet 14. Something to provide a sailing fix while my wife, brother and I rehab our International Dragon.

J. Dillon
12-10-2001, 07:41 AM

Sent you a wiring diagram I saved from my trailer. Check your E mail.

If any body else needs one , I'll send it to Photo point and post.


12-10-2001, 10:06 AM
Is there a factory provided trailer wire plug on a Volvo? Does the trailer's wire's plug fit it? (Probably not http://media5.hypernet.com/~dick/ubb/frown.gif ) If the above are no then you might be beter off facing the scorn of SWMBO and have it done for you. Perhaps by your friendly local Volvo dealer to avoid any future warrenty hassles.
It isn't rocket science but if the connections to the car's wiring are poorly done you could have problems with corrosion or open circuits to the tail lights. How much scorn would that earn you?

[This message has been edited by TomRobb (edited 12-10-2001).]

Bruce Hooke
12-10-2001, 11:06 AM
I'm not sure how precise the diagram is that JD sent you but I have to say that I have always found car wiring to be pretty confusing, with plenty of unpleasant surprises, and I am generally pretty good at wiring. For example on an '86 it's likely that the wire colors have faded so that what might show on the diagram as a brown and pink wire is now a tan and white wire. So, if it looks too confusing or if you are not confident about making good connections (wire nuts are not generally reliable on something that vibrates as much as a car does) then you might want to bite the bullet and call your local mechanic. I wouldn't bother with the dealer though - I expect the warranty expired on that care sometime early in the FIRST Bush administration http://media5.hypernet.com/~dick/ubb/smile.gif. On the other hand, even if you get it wrong it would be somewhat hard to get it so wrong that it would cost you more to have a garage put it right than it would to have them do it from the start so maybe you should just go for it (of course then you might have to face admitting to the mechanic that you messed up, which can be very good motivation for wasting a lot of time trying to get it right yourself!). Great cars those old Volvos. I drove an '81 for a number of years in the late 80s.

Ian McColgin
12-10-2001, 11:40 AM
Just tho throw an extra hook which I think is legal in most states -

I like to set up my lights and tag on a 2x4 fitted to lash down and secure the stern (about) of the boat. That way the wires can be furled up and the whole light assembly out of the way for launching. I just never believe that light assemblies are all that waterproof and I like the lights up and out where they will be seen.


bob goeckel
12-10-2001, 02:48 PM
you're gonna like my way best: after 3 hours fiddling with it i hauled it to the hitch place and they fixed it for $15.00. nuf said!

Alan Peck
12-10-2001, 02:58 PM
Regarding trailer lights. I have tried various types of waterproof tail/stop lights for trailers. None of them stayed waterproof. About ten years ago I discovered one that is made out of plastic and is completely open at the bottom. Trapped air keeps water away from the light socket and the small amount of water and or condensation that enters drains out. With this design it doesn't have to be truly waterproof. I have used these for years in salt water and have not had a bit of trouble.

Wayne Jeffers
12-10-2001, 03:09 PM
Trailer lights are such a pain, especially if you're dunking the trailer rather than launching with a hoist.

I have recently concluded that the solution that Ian suggests is the only way to go.


12-10-2001, 06:34 PM
you're right to have that converter unit for the WoWoe. The red wire goes directly forward and ties into the pos of the battery (with a fuse). The next thing is to be totally sure that the trailer ground wire is indeed connected to the trailer ground. Some folk like to rely on the ball/hitch union to supply the elec connection, but that's dicey.
Thereafter I just get intuitive with the directions and trial&errorize it. And I used to be religious about disconnecgting the trlr before dousing it, but disc surge brakes discouraged that, and modern WalMart lights and connectors proved to be unbeatable.


charlie keller
12-11-2001, 11:43 AM
the open bottem type are a good choice. anyauto parts store will have wireing diagrams on the back of trailer part packages.

Gresham CA
12-11-2001, 01:47 PM
Guys, This isn't like trying to find the bad bulb on the tree. The converter should be marked as to left, right, running and ground. If not, then a test light or volt/ohm meter will tell you which is which. On the trailor side it's just 4 wires. If you don't wire it to standard colored diagrams but it works, let the next guy figure it out. He's likely gonna have to put new lights on it anyway. I say spend the money you are gonna pay someone else to do it on a v/o meter and them you will have it for the future. Merry Christmas,

Charles G.

12-14-2001, 12:20 AM
For what it is worth, you can get (apparently) good info if you search for "troubleshooting trailer wiring" on Google.com.

I tried it, but can't stop the flashers when the running lights are on, so I took it to the dealer!

Alan D. Hyde
12-14-2001, 10:43 AM
I hate wiring, but there's little we can't learn if we force ourselves to do it. I suggest you buy the books and force feed all the key principles into your unwilling brain.

That way, when you're out on the water, and something goes wrong with the wiring on your BOAT, you'll be able to fix it.

I try not to take anything out on the water that I can't, at least temporarily, fix for myself.

Amps equals watts over volts. You need a hot and a cold line to each bulb filament you wish to light, and maybe a ground. The plug from your car will have tie-ins to the tail-light and brake-light and turn signal circuits. Just figure out which is which, and wire accordingly.

I know you don't like it; neither do I. But I'm sure you can do it just the same. Make yourself do it; you'll be a better sailor for it.


12-16-2001, 01:23 AM
are you trying to wire the car or the trailer here..my vote is the car..but Im not sure anymore.

I can tell you its not hard for someone with a bit of apptitude..SO..buy your favorite mechanic a six pack and watch..ask him to explain so you can troubleshoot the thing yourself later. Just getting it done shouldnt cost enough for even the cheepest to groan too much. and besides that, if your car burns to the ground you will have someone to make pay for it...!!

12-16-2001, 12:15 PM

If there's a U-Haul or towing hitch seller/installer near you, they are experienced at installing these connections on all types of vehicles. I've had them do it a couple of vehicles at very reasonable rates. I don't kid myself that I'm any good at electrical stuff either. Good luck.