4 pin wiring to battery on 77 Scamp

[GreatDane76]

Hi everyone... I searched the forum but couldn't find an exact answer to this wiring question so hopefully someone here can help me.

I just purchased a 77 13' Scamp but the wiring has been redone several times over and poorly at that. The wires are very faded and mismatched to the original harness so I'm going to tackle rewiring it myself this weekend using the wiring schematic in the Document Center. I'm doing this using a 4pin flat connector wiring harness on my Isuzu Rodeo.

My question is... should the white ground wire from the trailer harness be grounded directly to the frame of the Scamp and then run into the Scamp to ground the signal and marker lights - bypassing the battery altogether? Or should I splice the white ground wire so it's connected to the negative terminal on the trailer battery as ground - bypassing the frame? Hope this makes sense. I've searched online and I've seen it wired both ways.

Thanks!!

[Thomas G.]

I would ground the white wire from the harness to the frame (solder it to the steel) and then run a separate ground wire to the lights and brakes.

If you charge your battery from the tow vehicle, I would also use the frame as a conductor, meaning connect the battery negative directly to the frame with a 10 gauge or larger wire.

[GreatDane76]

Thanks Tom! I've only had this Scamp for about 3 days and the wiring was redone by a "skilled homeowner" at some point along the way.

Apparently the white ground was never attached to the frame and was run through the negative battery terminal.

One more question though... is it possible to charge the battery from my truck through a 4-pin harness? You mentioned attaching the negative battery terminal directly to the frame so will that charge the battery while I'm towing it?

Thanks again!

[Thomas G.]

Originally Posted by GreatDane76

Thanks Tom! I've only had this Scamp for about 3 days and the wiring was redone by a "skilled homeowner" at some point along the way.

We all have our previous owner stories.

Apparently the white ground was never attached to the frame and was run through the negative battery terminal.

The frame doesn't need to be grounded unless something is attached to it that uses electricity (like lights). Best to keep the frame out of the circuit unless charging battery, where it serves as a large conductor.

One more question though... is it possible to charge the battery from my truck through a 4-pin harness? You mentioned attaching the negative battery terminal directly to the frame so will that charge the battery while I'm towing it?

Thanks again!

Generally this is done with a 7 pin connector. You could add a second plug of some kind just for charging. In order to maintain an adequate voltage, you need to use quite large wires (10 gauge or larger)

[john warren]

to the frame. nothing on the four pin goes to the battery. you only hav ground, running lights, brakes , and turnsignals. nothing to do with the battery.

[floyd]

Don't confuse house wiring with DOT road wiring.
Dot wiring (the four plug) does not, and in my opinion should not, be grounded to the frame on a Scamp. Instead I always provide a ground back to the plug through the white wire.

Brown wire= Running lights
Green wire= Right turn/brake
yellow wire= Left turn/brake
White wire= Ground

Here is E-trailer's take with a lot of helpfull info.

Trailer Wiring Diagrams | etrailer.com

Note: They wire the ground to the frame, which I don't do since the trailer is fiberglass and the wiring can be inside the body with all connections protected.

Your "DOT" wiring is dependent and centered on your Tow Vehicle's wiring.

Your 12 Volt "House" wiring is dependent and centered on the house battery/converter.

You can add a harness to your TV to supply charge power to the House battery while towing, with the addition of a "two plug" or with the conversion to an RV plug.

[john warren]

Originally Posted by floyd

Don't confuse house wiring with DOT road wiring.
Dot wiring (the four plug) does not, and in my opinion should not, be grounded to the frame on a Scamp. Instead I always provide a ground back to the plug through the white wire.

Brown wire= Running lights
Green wire= Right turn/brake
yellow wire= Left turn/brake
White wire= Ground

Here is E-trailer's take with a lot of helpfull info.

Trailer Wiring Diagrams | etrailer.com

Note: They wire the ground to the frame, which I don't do since the trailer is fiberglass and the wiring can be inside the body with all connections protected.

Your "DOT" wiring is dependent and centered on your Tow Vehicle's wiring.

Your 12 Volt "House" wiring is dependent and centered on the house battery/converter.

You can add a harness to your TV to supply charge power to the House battery while towing, with the addition of a "two plug" or with the conversion to an RV plug.

yes your right, i'm used to trailers where the lights ar grounded to the frame, this most likely isn't the case with lights mounted on a fiberglass trailer.

[Byron Kinnaman]

Originally Posted by john warren

yes your right, i'm used to trailers where the lights ar grounded to the frame, this most likely isn't the case with lights mounted on a fiberglass trailer.

Having poke around at my Scamp wiring I can assure that there's only one connection to the frame. That happens to be the "GROUND" wire coming into the trailer via the 120 Volt cord. The 12 volt system gets to the frame through the converter and it's 3rd wire ground on it 120 power cord. That's it, there aint no more, unless somebody has rewired and tried to second guess the engineers.

[GreatDane76]

Thanks for all the info guys! My wiring is definitely a mess so I really appreciate the advice and input before I rewire it myself.

Unfortunately I don't have a AC -> DC converter in my Scamp. It would be nice to have but that'll have to come later I guess.

I do have a 120v AC plug wired directly to a 15 amp circuit box that only powers the fluorescent light and a single 110v outlet. I'll be adding a dorm size refrigerator later that will use this as well.

The water pump, range hood, cabinet lights, and an aftermarket DC outlet are all on 12v DC and wired directly to the battery with their own lead wires independent of the trailer harness.

The trailer lights were apparently grounded to the negative terminal on the battery for some reason (still trying to wrap my brain around that) but I take it that's not necessary and I should just leave the ground off the frame and let my tow vehicle's wiring supply that.

[GreatDane76]

Correction... I just bought a AC > DC converter for my Scamp

So the rewiring project continues to evolve...

[RogerDat]

Really don't need the tow vehicle to charge battery. A modest solar cell and a small AC battery charger would cover you for most of your needs.

If you do want to use tow to charge trailer it would probably be worth going with the 7 pin plug on the tow. You can always add wiring and hardware for charging later and use an adapter to 4 pin for the short term or other trailers.

[GreatDane76]

I really like the solar panel idea... definitely going to look into that more once I get the wiring completed as well as a few other projects.