Blowing fuses

Estroka · 08-14-2018, 08:51 PM

Hi all, looking for some help troubleshooting an electrical problem. It’s a 2016 2417, on a recent camping trip plugged into shore power and popped a 20 amp fuse that leads to the monitor panel. It was raining on the trip which probably contributed to the problem. (I suspect the trip when plugged into 110 was incidental.)
I’m trying to troubleshoot at home with limited results. The fuse blows instantly with no shore power and just on battery. There is no power to the monitor panel, and stove igniter. There is power to the radio, antenna and the fridge. The furnace doesn’t turn on, but I didn’t check voltage at the thermostat.
There was water inside the wiring connector box leading to the air conditioner. That would be a safety issue, but has no effect only on battery. I’m suspecting water caused an issue, but I’m not sure where to start.
Any ideas?

Thanks for the help!
Eric

**Bill** · 08-15-2018, 10:09 AM

Eric -

Do you have your blue book? If so, dig out the owner's manual for your trailer, and find the wiring diagram. TM wired the power distribution differently in different years and models, so it is really helpful to find the manual for your trailer. Once you have it, the first thing to check is whether there are any other loads fed by this particular fuse.

If the only load is the monitor panel, a 20-amp fuse is way too big. In my TM, the fuse is 7.5 amps, feeding the monitor panel alone, even though the panel itself requires less than 1 amp.

The fact that a 20-amp fuse blows instantly (in other words, a really big overload!) suggests to me that there is a short in the wiring behind the monitor panel. Since there are a number of wires that are connected to the panel, it is easy for a short to occur.

My next troubleshooting suggestion would be to disconnect shore power, disconnect the battery, unscrew the panel, and gently pull it out of the cabinet face. When you get it out, lay it face down on a folded cloth or blanket. In other words, electrically insulated from everything else. Take your time, and look over the connections (any of them loose? broken?). Make sure no wire is touching one near it.

Assuming everything looks good, move on. For the next step, it is helpful but not required to have someone else watch the back of the panel while you reconnect the battery for a moment. Does the same fuse blow? Does the observer see any sparks?

I'm suspecting that the rain was incidental. Let us know.

Bill

Estroka · 08-15-2018, 09:17 PM

Bill,
I did pull the monitor panel and disconnected the water pump, fridge fan and water heater from the switches. It still blew the fuse instantly. I have the manual, but don’t believe the wiring diagram. It does show the monitor panel, fridge, radio and fridge fan on the same circuit. The radio and fridge still have power.
The wiring behind the fridge is a mass of wires, but nothing obvious sticks out. I will have to try looking in the panel while someone connects the battery. That could make the troubleshooting a lot easier. There has to be spark with that kind of load.

Thanks,
Eric

Estroka · 08-19-2018, 08:05 PM

For anyone with a similar problem, I did find a fix. The issue was a missing screw in the 12V cigarette lighter plug. The hot wire was touching the ground and blew the fuses. It wasn’t easy to see until I removed the exhaust shroud above the fridge.

I’ve used this site for ideas and fixes, maybe this one will save others some aggravation.

Eric

tentcamper · 08-19-2018, 08:54 PM

About 30 years ago, I had a fuse in a car that keep blowing. It ended up being a penny or dime one of my kids put in the cigarette lighter socket.

But your problem is strange being it only blew when when you plugged into shore power. I would have thought it would happen while on battery power?

oldstick · 08-20-2018, 06:57 AM

Quote:

Originally Posted by tentcamper

About 30 years ago, I had a fuse in a car that keep blowing. It ended up being a penny or dime one of my kids put in the cigarette lighter socket.

Had a car once where the horn kept tooting while going down the road. Pulled off the horn cover and found a dime inside where one of the kids must have been playing vending machine with the steering wheel.

Padgett · 08-20-2018, 08:07 AM

Way to troubleshoot is to replace the fuse with a light or buzzer. Then start pulling things. When it goes out/off there you are and no wasted fuses.

Estroka · 08-26-2018, 01:47 PM

To be clear, the fuses were blowing on 12v. I just noticed it after plugging into a campground during a rainstorm. When I got it home and started troubleshooting, I noted it was happening on 12v and on 120.

Problems should occur at the connections or run through a panel. Finding it was the challenge, since it affected multiple items on the same circuit. And the wiring is a big bundle, all tied together. The manufacturer did a decent job, there just isn’t a lot of room to run everything and access is a challenge.