# Wiring Troubleshooting



## maple lake duck slayer (Sep 25, 2003)

Like many on here, I am not an electrician but know just enough to get myself in trouble.

I went and bought a new wiring harness for my truck(7 pin) as it is wired for it halfway back the truck but only had the 4 flat at the back.

I got that wired in and bought the relay for the battery charge. All other fuses for the battery charge are in the inside fuse panel and present.

Last night, I put the plug end on the trailer and wired up all the lights, including running a hot wire into the trailer. This is where I have the issue...

Just to test the hot wire, I connected a fog light the hot wire and grounded it to the trailer. When I touched the light to the trailer, it sparked(a little is normal I know) and really bogged down the truck. I did a little testing and after a while, held the light on the trailer for a while...and burned through a 30 amp fuse.

Anybody know what may be wrong? Is it because that battery charge line runs from the alternator and is not made to run directly to a light? Do I have to run everything to a battery first and then run the power from the lights to the battery? Or maybe I need to run the hot wire to a different terminal, like the trailer backup lamps terminal?

Any help is appreciated, trying to get everything hooked up by the middle of next week.

Thanks,

Chad


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## wingaddict (Sep 16, 2009)

What make model of Pickup? and did it come with a factory tow package? This will help figure out the problem.
Also what guage wire is running back to the plug? 12g should be the bare minimum.

If I'm understanding you correctly, you are running the wire directly from the alternator? that could be part of the issue. (bogging the truck down)
I've ran hot wires directly off the postive post of the battery (with an inline fuse) or many vehicles with an undermount fuse box have a postive post that is deisgned to run hotlines or other power sources off of.
Keep it off the alternator, and run it right to the battery. (just make sure to shut off all your trailer lights if your truck will be not running for any long period of time) Also lose the relay, a 20 amp fuse between the battery and the plug should be fine.

Dont wire it off any other circuit like back up lamps etc. they arent designed to handle that draw.

Next get rid of the "flood light" and get yourself a test light. Go to any hardware or auto parts store and you should be able to pick one up for less than $10. This will help diagnose any future electrical issues as well.


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## maple lake duck slayer (Sep 25, 2003)

It is a 2000 F150, no factory tow package. All the wiring for the factory tow package is ran to the back of the truck, I just needed to install a new harness that tapped into that wiring and the tail lights to get the 7 pin to the back of the truck. This harness was direct from the dealer, it was plug and play. I did not run a wire to the alternator or battery...I am using the battery charge port on the 7 pin plug. Everything is wired factory on the vehicle side, with all fuses and relays in place.

In the trailer, I ran 10 gauge wire to the battery charge terminal on the 7 pin plug.

I will have inline fuses installed...I bought a switch plate that has four switches and two fuses from Cabelas. Just not quite to that point yet.

I am assuming that the truck(wired from the factory) has the battery charge wiring running from the back of the truck to the alternator? Like I said, if that is the case I think that is the issue and it needs to be run to a battery first, and dispersed from there.

Looking forward to more input.

Thanks,

Chad


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## wingaddict (Sep 16, 2009)

> I am assuming that the truck(wired from the factory) has the battery charge wiring running from the back of the truck to the alternator? Like I said, if that is the case I think that is the issue and it needs to be run to a battery first, and dispersed from there


.

It should go to your fuse box first.
What size wire is the hotwire (battery charge wire) that is on the truck? 
Where was the 30 amp at that was blown? Truck or trailer? 
I'm still scratching my head about the "bogging down" of the truck.


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## maple lake duck slayer (Sep 25, 2003)

It does go to the fuses and relay first before going to the back of the truck. The fuse that blew was in the truck under the hood, a 30 amp maxi fuse for the battery charge function. The hot wire under the truck is large, I believe it is probably 10 gauge, possibly 12 gauge.

It puzzles me also, because when I hooked the light up under the hood to the battery, it didn't bog the truck down at all. That is what leads me to believe that hot wire (battery charge) is run to the alternator and hooking something up directly to that draws too much power, leading to the blown fuse. Maybe putting the battery in the trailer is the way to go to fix that?

Anybody?


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## maple lake duck slayer (Sep 25, 2003)

Figured it out...I'm an idiot.

I'm used to white wires being ground wires...turns out on the fog light black is the ground, white is hot. I had it reversed. Tested stuff out last night and it appears to be working now. I have wires run, battery set, switch plate set, just gotta connect the wires and mount the lights and I'll be good to go. Hopefully I'll have no more issues.

Thanks for the input


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