Dim LED's

Switch or chassis negative (ground)

my first procedure would be to pull them out of where they are and try them in another fixture... the leds can fail, but not likely both at the same time.

I would be inclinded to say there is a wiring issue at the particular fixture that could probably be found by removing it and inspecting it for a loose ground or hot wire.
some fixtures have the wires rivited to the contacts, and Ive seen where these connections have not gotten tight enough in the manufacturing process, or loosend by the heat from an incandescent bulb that may have been in the fixture before...

it could also be a wiring issue upstream somewhere, but not as likely as the problem being at the fixture.

bad switch ?
bad negative/ground on that circuit ?

I'm going to try the old bulbs and see if they work. I agree it might be a feedback issue as the roads on I-10 have not been nice. I'll try the other suggestions after church and dinner tonight. On the road tomorrow so I'll have time each night until it is fixed.

Thanks and I'll update as I go.

dalenoel wrote:
I'm going to try the old bulbs and see if they work. I agree it might be a feedback issue as the roads on I-10 have not been nice.

A "feedback issue"? :h

I went and pulled, again, every fuse, checked and put them back in. None were bad. Tried the switch just because, and all the lights worked very well. Just like they should.

Glad it is all working but I still don't know what the problem was or is.

Thanks for the suggestions. This is on a Monaco A DP.

dalenoel wrote:
I went and pulled, again, every fuse, checked and put them back in. None were bad. Tried the switch just because, and all the lights worked very well. Just like they should.

Glad it is all working but I still don't know what the problem was or is.

Corroded switch contacts that were cleaned by exercising the switch. Still would like to know what a "feedback issue" is though. ;)

dalenoel wrote:
Tried the switch just because, and all the lights worked very well. Just like they should.

The problem likely will be back.
You NEED a multi-meter.

At one point you mentioned the inverter.
That is NOT a factor because the LED lights run off the 12 V battery supply.

Could have been a connection problem at the fuse holder.

Mandalay Parr wrote:
Could have been a connection problem at the fuse holder.

That was the only contacts touched so you must be right.