Trailer bake ?

[Mushin]

So I'm getting to the end of my build, little things take forever! I have never had a trailer with brakes before and I'm testing all my electric again.
My ? is, dexter axle, electric brakes, one wire to trailer frame, one wire to blue on 7 pin, correct?
Next ? is, if I'm testing the wiring NOT w trailer hooked to vehicle and using battery at the 7 pin, will the brakes not engage just by putting 12 volts on blue wire cuz trailer frame has no ground cuz not hooked to vehicle tow hitch? Make sense? Any help would be appreciated!

[H.A.]

If you connect 12v directly to the brakes wire, (from the spare battery sitting directly on your concrete floor for example for example ) it will apply the wheelbrakes at maximum force.
If everything is wired up as typical RV, Negative from the "test battery" must be connected to the trailer chassis.

Blue wire from the cars brakes controller, applies power at progressively graduated amount depending how firmly one is pressing the brakepedal of the car.

[halfdome, Danny]

I'd run a dedicated ground wire for each wheel to your highway wire junction box, can't depend on the chassis.
Danny

[Mushin]

The battery that will be in my trailer will no be grounded to the frame, it's strictly running my interior lights and my fantastic fan.
So saying that, does there need to be a ground from the 7 pin on the trailer side to the trailer frame? Then a corresponding ground on 7 pin on car side?

[Shadow Catcher]

I will second Danny, separate wires! I used heat shrink with glue splice.

[H.A.]

The battery that will be in my trailer will no be grounded to the frame, it's strictly running my interior lights and my fantastic fan.
So saying that, does there need to be a ground from the 7 pin on the trailer side to the trailer frame? Then a corresponding ground on 7 pin on car side?

There should be, its good practise to connect all negatives to chassis ground.
But would not be needed if the negative of your trailer brakes are wired directly to the negative grounding pin of trailers connector cable.

As an aside,
Do you charge the trailer battery from the car whilst towing ?
If so, That battery negative must also connect to the grounding pin. (Either via chassis or a direct wired connection.)

At the car, The negative grounding pin should be grounded to the car chassis (easier...)
or it could be routed & direct connect to the car battery negative terminal.

[Mushin]

Battery is not charged while driving, I have a portable Renolgy Solar panel I hook up if needed.
I only have 7 pin connector for the trailer brakes, or I would stuck with basic. 4 pin. So I will run the ground from my trailer side 7 pin to 1 of the brake wires, run the blue to the other wire. On car side blue from controller will go to 4 pin to 7 pin harness I bought, I'll ground white wire to frame and all should be good when both are hooked up! I hope....
Let me know if that sounds about right, and thx!

[Dale M.]

I use trailer frame for grounding lights so frame has ground bond in general from tow vehicle in place, BUT I use two wires directly from brake magnets to 7 pin connector on vehicle connector for brakes as I seriously do not want brakes to fail when I want them most.....

Dale

[Mushin]

I use trailer frame for grounding lights so frame has ground bond in general from tow vehicle in place, BUT I use two wires directly from brake magnets to 7 pin connector on vehicle connector for brakes as I seriously do not want brakes to fail when I want them most.....

Dale

I have now run 2 wires directly from brakes to seven pin, on to ground on to blue. When I use battery to test all I get is sparks. Double checked everything and nothing is shorted out. Took both wires right where they exit the axle and hooked em to battery and still all I get is sparking. Could brakes or wiring in the hubs be the issue? His is all that's keeping from the road!

[Mushin]

Got em working! Thx to all who helped me out!

[OverTheTopCargoTrailer]

So what was the problem, don't keep us in the dark ??

[Mushin]

I bought a seven pin cable for the trailer, np there. Then I bought a 4 pin to 7 pin from the vehicle side. I was testing with that plugged into the trailer side without the car involved, just using a battery. Well come to find out the 4 to 7 pin plug was not wired in relation to the trailer side. Stop wire was left turn, running lights were not even hooked up inside plug, screw was out of it! Brake wire was wired to ground, it was all jacked up so I rewired it all to match up! Hours were wasted and bad words were said!

[H.A.]

.

[Mushin]

Yep, live n learn, now I know

[Dale M.]

I bought a seven pin cable for the trailer, np there. Then I bought a 4 pin to 7 pin from the vehicle side. I was testing with that plugged into the trailer side without the car involved, just using a battery. Well come to find out the 4 to 7 pin plug was not wired in relation to the trailer side. Stop wire was left turn, running lights were not even hooked up inside plug, screw was out of it! Brake wire was wired to ground, it was all jacked up so I rewired it all to match up! Hours were wasted and bad words were said!

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Dale