Friday, August 14, 2009

Trailer Hitch and Wiring

I also did a little work on the trailer wires and hitch setup last weekend. The wires turned into a rat’s nest of splices, dangling wires, broken grounds and lots of small pin holes in the insulation from years of testing. I cut the wires far enough back to avoid any trouble spots.

I saved the cluster as reference for matching wires since the lights worked off and on during the journey from Wisconsin. I also took pictures when I disconnected the lights for painting to cut down on confusion. For the new harness I purchased a trailer end harness for about $6 from Wal-Mart. It was a little short, so I soldered another length of trailer harness left over from a previous trailer project that was in my wiring toolbox.

I used a length of old compressor air hose that I salvaged from my dad when he got a new one to cover the harness where it comes up from the belly of the trailer.

This helps protect the harness from shorts as it rubs on the frame during transit or should I forget to plug it in and drag it down the highway. Would I do that? Nah, never.

Should you have an already dissected harness and you are wondering what is what, here is the skinny. On the trailer, the green wire goes to the four teardrop lights, the license plate light and the small running light bulb in the Bargman taillights.

The black wire goes to the dim filament in the large bulb in the Bargman taillights, sort of a second running light. The red wire goes to the bright filament in the left Bargman,

the left turn/brake light.

The brown wire goes to the bright filament in the right bargman, the right turn/brake light.

When you hook up a modern four-post harness to the existing wires, it should look like this: harness white wire grounded to the frame and body of the trailer; yellow left turn/brake wire connected to the red left/brake light wire on the trailer; green right turn/brake wire connected to the brown right turn/brake wire on the trailer; and finally, brown running light wire connected to the green running light wire on the trailer.

I also connected brown wire to the black wire. I think that you could either connect this wire to the running light system or just cut it short and leave it disconnected. I used wire nuts to connect to the wiring on the trailer so that I can change things up in the future, i.e., trailer brakes, charging system, back-up lights, etc.

I reused the existing bargman taillights. The bases were pretty rusty, but I wire brushed around screw holes for better grounding and replaced the bulbs using contact silicone to prevent highway light flicker. I reinstalled the bases using putty tape to insure no water leaks behind the base.

I cleaned up the lenses and put them back on.

If Vintage Trailer Supply gets their new replacement lenses for the Bargman Taillights, I may replace them, but for now they are fine.

For the teardrop lights, I ordered the Teardrop Marker Lights from VTS. Mine were rusted beyond repair and one was missing. These replicas have an aluminum base and the screw holes match perfectly, and at $5 each I thought they were a great deal.

I used a little putty tape on these as well.

I used wire nuts to connect all my lights. I like them better than crimp splices, and in the future I won’t have to cut the already short wires again.

Someday I may put LEDs behind the teardrops and the brake lights, if I have problems with burnt out bulbs.

After I got the lights functional, I moved on to the hitch. I bought new safety chains from Wal-Mart for $10 and a Reese Pro Friction Sway Control from eBay for $45. For the chains, I drilled a hole on either side of the hitch and attached them with ½” Grade 8 bolts. This way I can cross the chains to make a cradle in case the trailer comes off the hitch. The old chains attached at the same spot on the trailer, making this impossible before. For the sway control I had to drill five holes for the plate and bolt it on with 3/8” Grade 5 bolts.

I had a welder buddy of my father-in-law’s weld up a sway hitch attachment on the hitch that I had already been using.

I tested out the new setup on the way home from the farm and it worked great. I had trouble with sway before the sway bar when passing a semi on the highway, but now that isn't a problem. For $45 it makes for great peace of mind.

All in all, it was a very productive weekend.

So, if you are following along, so far we have:

Trailer $900

Bearing Repack $100

Steel $10

Sealant $10

Fan-Tastic Fan $140

Three Sheets 1/8 Birch $50

3M Polish $18

Buffer Pad $12

Mothers Aluminum Polish $8

TSP Cleaner/Paint Prep $8

Rollers, brushes and trays $30

Frog Tape $10

Etching Primer $5

Goo Gone $3

Paint 3 Gallons $98

Foam $250

Upholstery Fabric $510

Curtain & Pillow Fabric $80

Glass $50

Glass Seal $72

Backframe Gasket $80

Pile Weatherstrip $6

Vinyl Weatherstrip $5

Silicone Discs $5

Butyl Tape $15

Screws $70

Chains $10

Harness $6

Teardrop Lights $20

Sway Bar $45

Bringing our tally to: $2,626

Until next time dear readers, shasta la vista...


  1. Hey Jeremy,
    This has been a huge help to me, thanks. wireing has always been my weak point...I think you would be a great asset to my web community for old trailers!
    B.Tal 1963 shasta astrodome (under construction)

  2. nice guide! thank you!/I love it ! Very creative ! That's actually really cool Thanks.

    Trailers Parts

  3. Hi Jeremy-
    just purchased a 1959 Forester and am trying to locate 1/8 in Birch - can you share your source?
    Much appreciated!

  4. I love the picture of the 7-pin connector cluster! Looks exactly like the one on my 1961 Compact-- it disintegrates every time I touch it. This was very helpful. Thanks!

  5. On the trailer, the green wire goes to the four teardrop lights, the ...

  6. Just handed over deposit on a 1965. Looking forward to the same shopping list.