You obviously have a wiring problem in your truck. I would start at the truck's receptacle and check the wiring where it screws into the terminals. Then, working forward, check every inch of the wiring harness, especially where it crosses over or through the truck's frame. Any spot where you encounter chafing or pinching of the wiring should be suspect. Look at the wiring junctions and follow it all the way to the fuse block. The harness can be crushed by a rock, chafed by a broken cable tie or damaged by any number of ills. You will have to spend the time or take it to a mechanic.

BOL  Gard

On my Ford SD PSD, there is no aux power to the plug until my engine is actually running. Just having the ignition switch in the "on" position will not work. I cannot check my circuit for power unless the engine is running, the point where your fuse blows. So you still have a short in your truck's wiring.

BOL  Gard

Burner

As an aside, sometimes it's very difficult to find a broken or chafed wire within a loom, especially when you may be inspecting almost the whole length of the truck. There are times when it's easier to cut the wire at both ends and run a new wire, saving pig tails at the fuse box and receptacle onto which you can affix splices. Follow the existing loom, secure with cable ties and cover with the split type of flexible wiring harness. Make sure the replacement wire is the same guage wire as the original, to insure the new circuit has the same capacity as the old.

BOL  Gard

Gard,

I should have prefaced my previous with "I don't know any electricity"!!This probably won't be a magic bullet, This trailer is a 95 Featherlite and is "new" to me. Anyway, there is a Magnetek convertor/charger 7200/7204 in it. So in essence, If I plug in to a shore line, the power from extension cord goes in to a dual 15 amp breaker box, one goes on to Air Conditioner, other goes to duplex outlet the convertor is plugged in to. Out of the convertor to a line which is spliced into and powers interior lights.

My lengthy discertation boils down to, is it possible, with those 15 amp breakers thrown, it is pulling too much juice? And if I keep the breakers off, is it possible it won't pop the fuse???

Thanks,

Let's see if I'm understanding what is happening correctly: Your trailer has a 15 amp circuit with a converter/charger that powers your interior lights. When you try to power the same circuit using the truck's aux circuit, it blows the truck's fuse. Is this correct?

The truck's fuse is a 30 amp circuit. This fuse blows whether the truck is wired to the trailer or not? Are these statements correct?

I don't know what you mean when you say the breakers are "thrown". Do you mean they are open (off) and no current is flowing, or are they closed (on) and there is a current.

The first thing that has to be decided is if the problem is in your truck or trailer. I was under the impression that you truck's wiring was at fault. This is not correct? Does the truck fuse blow with out the trailer being attached?

Let me know    Gard

The breakers when energized when it was popping the fuse on the truck.. Now I've got a fuel issue on the truck....leaking valve. Replacing the o rings and when I get power restored I'll check the truck by itself. I just threw out the previous as I put it "a magic remedy"....I'll dig more and isolate truck from trailer, then breakaway battery from the line and I'll let you know.

Thanks!!!

Gard,

I unplugged the trailer from the truck. Put a new 30amp maxi fuse in...pulled the relay, started the truck, fuse was fine. Plugged in relay, truck started, fuse fine. Plugged in trailer WITHOUT breakaway battery/charger hooked up, fuse immediately blew. All lights, turn signals, brake lights, electric brakes work fine. Just that accessory line in the 6 way that HAD the breakaway battery hooked to it. Won't do it with truck to "on" position only.....only running. I'm really lost....any ideas???

THANKS!!!!

I don't know what relay you're talking about. If the truck is behaving correctly with the trailer disconnected and you have power to the aux circuit with the motor running, then I would say the truck is not your problem.

I suspect the problem is with your trailer. Have you ever had a time of your trailer ownership in which you had no problems? Have you changed any wiring on the trailer since you've had it? Let's start with a process of elimination.

Gard

You can replace your fuse with a Napa circuit breaker for about $18

You have a dc voltage problem, so I would think that the ac shore line components can be disregarded. I would start trouble shooting by disconnecting the dc output from the charger/converter and anything else on the same line that is connected in your trailer to your b+ aux from your truck.

If you are blowing a 30 amp circuit with no load on it, it sounds as if you have a direct short to ground.

Gard

Sorry, no I don't. I bought a 20 amp breaker last year for $18. When I inquired about it, the counter guy knew nothing and said there was no such thing. Another person overheard us, dug in a parts book and came up with a whole list which included mine. It was a special order, they didn't have it in stock.

You install it in place of the fuse and forget about it. It auto resets when there is no problem.

Gard

An alternative to those expensive fuses is a 12 volt light bulb and socket.  Wiring a light bulb across the fuse terminals will let you know there's current flowing by the bulb lighting.  Yet, the amount of current passed by the bulb is safe for the wires.  Then start eliminating anything that is on that circuit.  When you've cleared everything the light will go out.  Then you've found your short.

When you are trouble shooting the electrical system of a trailer, it is helpful to have a power source other than your truck. If you damage your truck's electronics, it could be a very expensive proposition.

A 12v battery charger works well and most have an internal circuit to protect itself against a short or reverse polarity. Clip the ground wire (negative) to a clean spot on the trailer frame. Put a nail into the individual terminals of the trailer plug and touch it to the positive lead from the charger. You will then be able to power the individual circuits of the trailer.

If there is a short and the charger is making an unusual noise, do not leave the positive lead in contact with the nail, only momentarily touch it, to determine if it is working or not. The built in meter will tell you if there is a current flow or short.

Gard

Great advice....I actually just used my charger to recharge my breakwaway battery. I'm all over the place I know...should just do one thing at a time, however, can you give me some advice on electric brakes. My used trailer brakes were very rusty and worn...so I am in the process of replacing them with brand new units. I wired the brakes (polarity doesn't matter right?) and with the trailer jacked up, spun the wheels to see if they worked correctly. No, they didn't even stop a little. I put a meter on them, oh, I have a prodigy inertial, not timed, brake controller. The meter gave me readings from 4-6 volts......is that right?? Could the magnets be bad (2 seperate NEW brake units).

Thanks!

Did the brakes work before you replaced them? Did your trailer wiring work before you installed a battery charger? Is a pattern developing?

Gard

Did you spin the wheels going forward?  Some Electric brakes don't work at all with the wheel turning in reverse.

Generic trailer wiring can be purchased in running lengths by the foot. Sometimes it is easier and more reliable to change all of the older wiring harness at one time, than to have to keep trouble shooting additional problems. The cost of the wiring is far less than your labour, and is cost affective with the anticipation of fewer future problems.

BOL  gard