12V / 15amp fuse blows while towing w/fridge turned on 12 volt

While towing with fridge on 12v and running, we arrive at camp and 15amp / 12 volt fuse is blown. Fuse is on face of converter and is labeled for interior lighting. Top will not raise until I crawl in and replace the fuse. In 3 years have only had this problem the last 3 trips. Only thing I worked on lately has been the black and gray water tank monitors and that fuse is fine. Could it be anything to do with being hooked up and towing?

Freddie, somethings wrong with your wiring. That fuse should not have anything to do with the lift mechanism. I think maybe, somehow the lift circuit has gotten crossed with that fuse's circuit. The lift mechanism pulls far more than 15 Amps and would immediately blow that fuse. When you are towing, do you put the Master Switch in the center, towing position? That might stop the problem from happening, which MAY be caused by the movement during travel.

How are you at tracing circuits with a multimeter? It sounds to me like you may have some degraded insulation where wires run close together.

- Jack

15 amp fuse

What I do not get, is that the lights are out and top will not raise each time we have made a recent trip and arrive at our destination. I replace the one 15 amp fuse and lights are back on AND top will now raise up. I have a 1990 model 22 foot, 229L model. I would think that if lift is on separate 30 amp fuse that it would still raise even when lights are out. Have only had to deal with this one fuse.

I haven't been able to find a 1990 manual, but there MAY be one in the library that I missed. I found one for 95-96 models and the wiring might be the same in your trailer. If you look on page 19, drawing A, in the manual here: https://www.hilotrailerforum.com/f49/owners-manual-95-96-towlight-621/, you'll see that the lift system looks like it MAY get its power through a 15A fuse, which only protects the solenoid circuit, which is a fairly low Amperage path. It's a black wire connected to fuse #2. ALL of the there fuses seem to be connected to a buss bar that looks like it receives its power through the Circuit Breaker (C which is probably in the battery box. The lights seem to be wired to fuse #4. Fuse #1 is the water pump and Fuse #3 is the bath fan. All of the fuses in this diagram show only ONE wire out to an appliance. Do you have any that have more than one wire connected?

You also don't have a "Master Switch" in your trailer if it's wired like this one. Do you have the Safety Bar indicator light?

Sorry I can't be more help than this. The wiring in these earlier trailers is completely different than the wiring in mine.

- Jack

Update to my last post: I just ran across a manual for the 1990 Classic models. Here it is: https://www.hilotrailerforum.com/f49/owners-manual-1990-25ft-classic-2016/. Page 17 shows the wiring and it's the same as the one for 95-96 models. It should be what you have.

The only circuit you need to study is Drawing A.

- Jack

Thanks for the link to manual. In the morning I am going to trace these circuits and hope I find the problem.

15 amp fuse

Thanks for the link to manual. Used wiring diagram and do believe I solved problem. Also found a problem with 12 volt line to fridge. The in -line fuse link was getting really hot and had 12v into link and very little reading coming out. I replaced the fuse holder and all is well there and freezer gets really cold now running on 12 volts.

I do have two wires on some of fuse links on face of converter and all the links were labeled wrong. I moved the lift motor wire from # 1 to # 3 and on # 1 light circuit I did find an apparent shorting out when I jiggled the wiring under floor in upper cabinets. Now with the lights and the lift motor on different fuses and I have a problem then I have it pinned down to a specific circuit BUT am sue the light wiring was the problem and was blowing fuse and it was not lift motor circuit. As I said before, both were together on # 1. I only have 5 fused 12v circuits and I did relabel all of them.

Thanks again for the help.

You're welcome, Freddie. I suspect a prior owner has tried to "improve" the wiring.

- Jack

By pass all that undersized 12 volt wiring and run a much heavier gauge wire pair direct from battery with dedicated fuse in an easy access location. I used 6 gauge. That toy wiring RV manufacturers use to power a 12 volt fridge is a joke. Much more efficient for load it draws.