24 volt trailer wiring (again)

[Mr Tibbs]

I know this has been discussed before but today I had a different idea on how to wire the trailer lights in my HJ61. I first had the idea to just put 24 volt bulbs into my trailer and be done with the issue, but that will only work for one trailer. If I want to borrow a different trailer or rent one to help a friend move I'm SOL.

So, my question is can I wire in another converter in the back and use relays to turn the trailer lights on? 12 volt to the relay from the converter, and a 24 tap to turn the relay on, then 12 volt to the trailer wiring. Does that make sense? Will it work? If so I should be able to hook up to any 12 volt trailer and be good to go correct??

 

[lisponger]

I have the same truck, same wiring(24v) and live just a hop skip and a state beside you in Colorado.

My thoughts were the same as yours but I will also run into the same problem come winter when I occasionally need to tow a different trailer...

I was just researching this today and it looks like @Stone posted this about 10 years ago for a solution: https://forum.ih8mud.com/threads/trailer-lights-logic-circuit-step-down-voltage-converter.43609/

 

[Mr Tibbs]

That step down converter looks like the ticket, but damn it's expensive!! I would think a bank of relays and some wire would be cheaper. Then again I don't have the best track record with wiring.....

 

[HJ61 12HT]

The easy way is to add resistors in each line, all you need is a plug and socket and make up a little box of resistors.
Perhaps a metal box inline outside the car to allow heat to be dissipated easily...

 

[SteveJackson]

That step down converter looks like the ticket, but damn it's expensive!! I would think a bank of relays and some wire would be cheaper. Then again I don't have the best track record with wiring.....

I found the attached diagram here on mud and use this every time. I use 12V-50A relays from Radio Shack or any other source, works great, several units have multiple years without failure.

The easy way is to add resistors in each line, all you need is a plug and socket and make up a little box of resistors.
Perhaps a metal box inline outside the car to allow heat to be dissipated easily...

Have you done this with good results? I'm a little concerned about the constant heat for multi-light trailers when the running lights are on. Constant load could be a heat problem for the resistors?

 

[fireball]

Steve the drawing says to use 24v relays and you say you use 12v?

 

[The Dude]

I started off using 24V lights in all my trailers but it turned into a pain. If you have a 24-12 converter already it's a simple process. The resistors will produce heat, especially on your running lights. the others not so much. Using LED bulbs would help as well to keep amp draw to a min. Actually, now a days you could prob get LED trailer bulbs with a 12V-30V rating. Doesn't help if pulling a buddies trailer though.

You should be using relays with 24V coils unless you are using the resistors.. then 12V will work.

Here are the pics of my unit. I got the larger relay holders off of amazon but have switched over to the BRIC interconnects. (much smaller and hold fuses as well)

BRIC

6 Way Automotive Relay Base Holder Box for 4/5 Pin Relays - Lucas Rists 51158524 | eBay

IMG_4211 by Brad Taylor, on Flickr

IMG_3837 by Brad Taylor, on Flickr

IMG_3815 by Brad Taylor, on Flickr