If it seems like I'm doing a lot of posting lately, it is due to the long "after action (trip)" list of things to do. I replaced all the puck lights with LED discs - simple operation, not requiring getting into the wiring. The trouble is that the fuse to the port side bank (dinette and sofa) keeps going out. I can't see how I might have pinched a wire or shorted a ground. It doesn't happen immediately; only when turning on the lights. I'm using a 15A fuse and lower wattage due to the LEDs. Any ideas?
Internal short in one of your new LEDs
Have you experimented to see if perhaps one of the LED pucks is bad/misassembled?
They all come on. How do you test each one? Resistance?
Take out all of the bulbs except the first one. Turn on the lights. Start adding one bulb at a time. A 15 amp fuse is good for 180 watts, about 50 or more LED bulbs, way more than you should have on a circuit anyway. These LED bulbs may not have good voltage compensation and parts overheat. Your old halogen bulbs were 10 watts each.
These older puck light were subject to a lot of heat over a long time. The plastic parts where the G4 bulb pins go in get brittle and may not isolate the +/- adequately.
Do you have a slide? The passenger side ceiling lights are isolated from the drivers side when there is a slide by a relay. In my coach it is above the microwave. It is possible that this relay is having a problem. Mine buzzed with the very small loads of the LEDs. I bypassed it.
The new LED lights are 1.8 watts each and the two pin receiver appears to be ceramic.. Logic would suggest that they are less likely to blow a fuse than the halogen bulbs.
Start by assuming one is bad. Now design an experiment to see which one that is.
Like Roger suggests, put just one bulb in. See if everything is OK. If it is, put another bulb in another fixture. Repeat until the fuse blows. When it blows, set that bulb aside and try a different one (and a new fuse).
We have been buying LED pucks for years and have run into bad ones several times.
I have not worked with LED's, but wouldn't you be able to check with an ohm meter (much lower resistance/no resistance) as with any other light?
I'll start with an ohm meter, since that is the only qualitative test I can do.