Tow vehicle lighting and wiring question.

[ClydesdaleKevin]

Okay, we have a "new" tow vehicle, a 92 Jeep Wrangler with a hardtop. 

Our old tow lights are magnetic, so they won't work with this Jeep.  The simple solution is to just get the tow lights with the flaps and stick them in the hatch of the hardtop.

But I'd like a more elegant solution.

At the RV store the other day, I saw some universal tow vehicle wiring kits...little sealed boxes with input and output wires coming off of them.  They contain diodes so there is no backfeed to the RV lighting system.  Then you wire them into the tow vehicle.

Then your tow vehicle marker lights, brake lights, and signals work in conjuction with the RV's when towing.

My question is, is there an easy way to wire these things in, or do I have to run a new wire to each light that I want to operate?  The kits are cheap, so its not a bad plan, but is there a relay center or something I can just wire one harness into, or is it going to be an involved project requiring individual wires to each light?

Kev

[gadgetman]

Not sure on your jeep light setup, I have done three different vehicles and on all three there was room to remove the lights and drill one inch holes and simply install pop in 1157 sockets and run the wires to the ft. Another vehicle I had uses 2 bulbs for the tail lights, I removed one set and installed 1157 sockets there and just left the factory harness disconected for that set.

[ibdilbert01]

At the very least you should just be able to patch into the wiring harness under the dash.   

[Elandan2]

Hey Kevin,  At most auto supply stores you can get the 4-wire cable for doing up trailer lights.  You could get enough of that to wire up your lights and run it through the jeep to reach the connector coming from your MH and be able to simply plug them in.  The diodes probably allow you to hook up a system using separate turn and stop/tail lights on the motorhome to the new lights with a combination stop/tail/turn setup.  Rick

[gadgetman]

you only need the diodes to pull a vehicle that would normally a seperate turn/brake light. If the vehicle dosent have that you can just tage into the lights that are there but still may need a diode on the pos taillight so it dosent turn on the vehicles park lights, maybe even the dash lights, all depends on the wiring.

Thats why I find it easier to add a socket to the lights that are there,or delete one if its a 4 socket system. You could just add a socket set to a harness and remove the factory ones and install the towing ones for the trip, thats easy too. I just dont want TOW LIGHTS stuck on top of my vehicle.

[ibdilbert01]

For the folks who have never seen one of these kits...


http://www.etrailer.com/Tow-Bar-Wiring/Hopkins/38955.html
(Or search for Tail Light Tow Isolating Kit)


Basically the kit is designed to keep the rest of the towed electrical system from back feeding into the RV or the other way around.   The blocks actually contain "two" diodes inside. For those who don't know, diodes only allow current to flow in one direction, sorta like a check valve in plumbing.   I got out my magical markers and tried to draw a quick diagram explaining whats going on.   Because of the diodes, there is no way for current to back feed from the jeep to the RV, or from the RV to the jeep.   





Regarding Gadgetmans "separate tun/brake light" comment, thats another kit.   These kits are normally called "2 to 3 wire tail light converter" or "3 to 2 wire tail light converter". More information in this video below.  (Some cars and trailer share the brake lights with the turn signals)

http://www.youtube.com/watch?v=kFJgmybAPdo


If your car has a computer system that detects if the bulbs are blown, you might want to make sure the kit you buy is compatible.   I had a Grand Cherokee that I put a universal 3 to 2 tail light converter on it and from that moment on the computer thought all its brake and tail lights were burnt out.  After a few years of being annoyed with that, I built my own converter using optocouplers, but thats another story for another forum.   

[ClydesdaleKevin]

Thanks guys.  The wiring is pretty basic on the Jeep, and the computer only controls the fuel injection on the 4.0.

If I have time at this show I'll see about wiring in the lights directly, and if I absolutely had to run wires to each light I want to operate, then I'm not opposed to Gadgetman's suggestion, although if I had to add a light to each fixture I'd probably go with LEDs.

Otherwise I'll get the flap lights for the hatchback, and figure out the wiring in Carolina before our winter vacation.

kev