Flickering LED light blows circuit??

[Vladimir]

The light over the stove in my Casita Spirit trailer started flickering. I assumed it was a poor contact and tried seating the light. Nothing seemed to help, but once when I seated the light and turned it on it quite working and I did hear a slight tick noise. I assumed that I blew the light. 

After that adventure, I noticed that the shower light and the two lights over the dinette turned on but very dim. Also the hood fan quit working. I opened up the fuse box and it looks like circuits 2 and 3 the fuses are fine, but there is a red light behind both fuses and it is lit RED. 

Does that mean that both fuses have blown and need to be replaced?? Both are 30 amp fuses. 

Anybody have a clue....I sure don't.

 

[Kirk W]

11 hours ago, Vladimir said:

Does that mean that both fuses have blown and need to be replaced??

Most fuse boards that have the red LED put it there to indicate a blown fuse. It is designed to carry no current unless the fuse opens up, creating an infinite resistance. The only certain way to know if a fuse is good is to measure it with an ohm meter. A reading of 0Ώ is a good fuse and anything more than 10Ώ is bad. 

If you have a 30a fuse that is open, there is a good chance that the problem was more than just an led light. 

[oldjohnt]

Those fuses are either blown or they aren't. Often a visual inspection can see if the fuse element burned and is opened or not and a simple DC continuity test light or an ohm meter as Kirk mentions can verify. Open circuit approaching infinity ohms BAD,,,,, Closed continuous circuit near zero or low ohms GOOD.

 Id "first" guess dim lights are due to a loose/burned resistive wiring connection or a bad/resistive switch somewhere in the circuit (or even the lamp base itself)  which drops voltage (V = I x R)  leaving less for the dimmer light. As long as a light glows dim the fuse isn't blown total open (or perhaps there's an alternate resistive current path, lamp etc. ??).....If the fuse blows complete open there must be a short in the wiring and if not fixed it will just blow more fuses in the meantime. Its possible to have a "minor" x ohms resistance short that's NOT drawing enough current to blow a 30 amp fuse.....

 Connections,,,,,,,,Crimps,,,,,,,,,Butt Splices,,,,,,,,,,,,,Bad resistive switch contacts,,,,,,,,,,Wiring shorts,,,,,,,,,,Blown fuse but alternate resistive current path allowing for dim light,,,,,,,,,,,,,,,all come to mind.

 If you start at the beginning source of the circuit you should have near battery voltage, but if down the line after connections or splices or switches (with load like light applied drawing current) the voltage drops YOU FOUND THE PROBLEM. Of course, a short bad enough to blow the fuse may be the problem. Get your 12 volt DC test lamp and ohm and volt meter and go to work  

PS this assumes a good strong reliable voltage source upstream (battery or charger etc) and the problem is in the lighting branch circuit NOT at the source

 

 John T

[lenp]

If the light was turned ON when you were re-seating the bulb, you may have shorted the circuit.  Replace the fuse and make sure the bulb is seated properly and try again.

Lenp

[Wrknrvr]

 I have found if you are questioning a fuse pull it out and put it somewhere as that it will not be used again. Atleast not now. Put a new one in.

 

 Through the years doing RV repair for a living. A fuse can look good? It can test good? 

 And it can even not light that red light.

 Several years ago I had a custom check a 2 amp control fuse on his wipers. I travel 80 miles round trip. Stick a new fuse in first thing I did .

 

 Wipers work fine.

 

 Just this week I was helping a customer replace the electric day night shades in a King Aire motor home. New shades had 3 wires, old shades had 5 wires.

 

 Called Newmar for tech support and received a service documents on replacing the units.

 Very frustrating as the blinds seam to have a mind of there own. Cannot program them. But they seam to work some.

 

 This the lesson on fuses. The unused two wires were for each blind where just sniped off. They were joined together, side to side , so just use a side cutter.

 

 In that process we had one fuse blow and show a red light. Two fuses blow and not show the red light. One fuse that you could not see where it was disconnected.

 

 So finally separate each set of wires that were not used. Dead end them properly. New fuses and now everything operates and could be programmed.

 

 You can have a fuse blow apart and still test good and not light that red light. 

 

 Safe travels,    Vern

 

 

[Vladimir]

Thanks for all the replies. I just got back into a cell service area after a few days.

I talked to a friend and he suggested waiting until I get a supply of replacement fuses, before attempting to diagose a repair.

It turned out to be a blown fuse. One blown fuse. Not sure why the other circuit lit up and the LED lights came on very dim. He suggested that it make be a connection along the neutral wire.

Anyway, one blown fuse. Now I have to find another LED light!!

Thanks all the replies. I learned some new stuff.

[oldjohnt]

1 hour ago, Vladimir said:

Not sure why the other circuit lit up and the LED lights came on very dim. He suggested that it make be a connection along the neutral wire

 Makes some sense to me:  If the fuse was completely blown and open but there was still some albeit small current, it had to be via some alternate resistive path. Its a bit similar to when there's a bad ground or faulty wiring in a trailer so the return current finds other paths causing some bulbs to glow dim.

 Oh well congrats and thanks for the feedback

 John T