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Need Help - Trying to figure out how to wire a 7 wire trailer connector to my 1957 Buick Harness


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Hi,

 

I am in the process of setting up my 1957 Estate Wagon to do some towing of our new Shasta AirFlyte trailer, and I am stumped on how to wire in a 7 pin connector, specifically regarding the brake and turn signal set up. I have a separate wire for the brake lights and a separate wire each for L/R turn signal lamps. The 7 pin connector assumes, based on current modern vehicle wiring, that the L/R wires also run the brakes. Hence there is my conundrum. 

Can I just jump the brake wire to the L/R wires on the connectors with a splice? Or do I need a converter to take the brake signal and and integrate it to the L/R turn signal. Any help would be appreciated. Thanks

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What you need is a conversion box. It will have inputs for both turn and stop and outputs a combo stop/turn wire. It’s been quite a while since I had to use one

 

check etrailer or google turn signal conversation box. The one from etrailer is about a hundred dollars 

Edited by Mike "Hubbie" Stearns (see edit history)
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you do not need all the outlets? unless you have an electric brake controller for brakes on the trailer.also one is ground one is 12?volt power to trailer for?that leaves left right and taillights.the wiring is based on GM for L R T.you will find the yellow wire goes to the red post and the brown to green post and green to brown post.wired a ton in my time wiring trailers and plugs.this is if you are using a 7 for trailer.there is an easy way if you just want tail and left right.

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You have to use a brake controller or you will be locking up the trailer brakes every time you hit the brake pedal.

The brake controller is not that hard to hook up but you will need to run some wiring from the controller to the bumper.

Don't even try to run trailer brakes from the lights, believe me, this is what I did in my prior life.

Like this or similar, available at NAPA I am sure.

I prefer the ones with the thumb wheel, for quick adjustment.

 

https://www.amazon.com/Tekonsha-90160-Primus-Electronic-Control/dp/B001P11SCM/ref=sr_1_2?dchild=1&gclid=EAIaIQobChMImOiNobHi7QIVFxmtBh0f5Q2lEAAYAiAAEgIXTPD_BwE&hvadid=256371831309&hvdev=c&hvlocphy=9032911&hvnetw=g&hvqmt=e&hvrand=5849745161927945453&hvtargid=kwd-300953242540&hydadcr=7062_9585710&keywords=brake+controller+for+trailer&qid=1608667473&sr=8-2&tag=googhydr-20

 

Edited by JACK M (see edit history)
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Wait what?!!

 

22 hours ago, 1957buickjim said:

I have a separate wire for the brake lights and a separate wire each for L/R turn signal lamps.

 

Are you sure? That doesn't sound Buick-like to me, though I don't have a 57 wiring diagram to look at. I would expect the brake/turn bulbs to be shared in the Buick. Do you mean they are separate on the trailer? Or, did you mean the Buick?

 

22 hours ago, 1957buickjim said:

Can I just jump the brake wire to the L/R wires on the connectors with a splice? Or do I need a converter to take the brake signal and and integrate it to the L/R turn signal.

 

21 hours ago, Mike "Hubbie" Stearns said:

What you need is a conversion box. It will have inputs for both turn and stop and outputs a combo stop/turn wire. It’s been quite a while since I had to use one

 

check etrailer or google turn signal conversation box. The one from etrailer is about a hundred dollars 

 

This is the correct answer if the brake and turn circuits are truly separate on the Buick.

 

The trailer standards in North America have the brake/turn together normally. That is why the plug is the way it is. Most older American cars match. Most North American trailers match. The boxes were generally needed for imported cars in the past, especially ones from Japan. Some newer American cars may need it too. Conversion boxes are a necessary evil in those cases. They are unreliable, but there is no better non-invasive way to do it. Some people add relays to limit the load on the conversion box (and the car wiring too). You've been warned...

 

53 minutes ago, JACK M said:

You have to use a brake controller or you will be locking up the trailer brakes every time you hit the brake pedal.

 

Yep. If it has electric brakes, you are gonna need a controller.

 

.

 

 

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To expand on the tail/stop/turn issue, most trailers and 1960s-vintage US cars use 1157 bulbs in the tail/stop/turn light positions. These bulbs have two filaments with a common ground. The low wattage filament is used for the tail lights. The high wattage filament is used for the stop and turn functions. The turn signal switch in the column normally connects these high-wattage filaments to the brake light circuit, but if you operate the turn signal, the switch disconnects the high wattage filament from the brake circuit on the selected side and instead connects it to the turn signal flasher circuit. Basically, this overrides the stop light function on that bulb. You can connect the tail light circuit directly to the low wattage filament(s) in the trailer bulbs, but you have to merge the stop and turn circuits from your car into a single signal at the trailer. There are two ways to do this, one is to fab up your own "converter" circuit with relays (many newer vehicles do this as part of the vehicle wiring) or you need to buy a converter box that does the same thing. Curt and Reese both sell such converter boxes.

 

https://www.curtmfg.com/learn-more-tail-light-converters

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