I have a 1987 fun lite hi-lo camper 8721 fll. All of the 12v lights inside and outside the trailer are not working. I am able to raise and lower it with no problem. Additionally the battery is charging. I dont know if it will charge from the vehicle while towing as I have no exterior running or brake lights so Im using an add on set of brake and blinkers. The lights dont work even when plugged into shore power.

I located the converter under the couch, I opened the panel and there are 4 fuses I have good fuses in but there is only power on one. Does anyone know if there are additional fuses inside the converter? Also if a new converter is necessary Im guessing an exact replacement is gonna be a chore to find. Can someone point me in the direction of a replacement and info on wiring it properly.

William, welcome to the world of HiLo! I'm guessing your Master Switch is in the Raise/Lower position for the top. It is a 3-position switch that is located near the Up/Down switch. Flip it to the opposite extreme - the "Camping Position" and you should have lights inside, as well as fans. water pump and so on.

Now, the exterior running and brake lights are a different problem. They get all their power from your tow vehicle, not the trailer's battery. You may have a problem in your tow vehicle's wiring - have you checked the voltage at all the positions in the 7-blade plug? There is a simple plug tester you can buy on Amazon (and other places) that will allow you to do this easily.

- Jack

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Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH, Progressive Dynamics Converter, Fan-Tastic Fan, LiFePO4 battery 12V DC Electrical System, SoftStartRV mounted on A/C
2024 F150 Platinum FX4 3.5L PowerBoost SCrew

I have water pump at least on shore power. I haven't tried while disconnected. I only have one switch for raise lower I do not see a master switch. There is a pull cord to engage raise lower.

Thank you William - your symptoms sounded perfect for the typical Master Switch problem.

So, it sounds like you have a wiring fault, which is fairly common in older trailers. Rats and mice like to chew on wiring and they can easily cause this to happen. And, over time, connections become corroded or disconnected, which leads to the same symptom.

We don't seem to have any owner's manuals for the 87 model year trailers, but here's a link to a 1990 model year one. https://www.hilotrailerforum.com/f49...-classic-2016/ HiLo published "generic" manuals for all their models in a year production, and, there was very little change in construction from year to year, so I suspect the wiring diagram in this manual matches yours. This one shows 4 fuses, and no Master Switch, so I suspect it is like yours.

I doubt your converter is bad. A faulty converter would not stop the interior lights from working directly from the battery. But, you are not getting DC 12V power to lights and probably a fan. My first guess is that you have a bad ground connection in the light circuits, and this could include the exterior lights too. It's going to take a tedious bit of tracing with a multimeter to find the problem, I'm afraid.

- Jack