Lights bright to dim

[seraby22]

I have a 1998 Fleetwood Discovery 36T.
Batteries are good, inverter/converter is good and all fuses are good.
My problem is one circuit for 12v lighting is having issues. The rig is parked along side my house and plugged into 30 amp outlet.
I left the two overhead bedroom lights on all night long. In the morning I turned the lights off. About 3 hours later I was back inside and turned the lights over the bed back on. They came on full brightness then immediately went dim. I've hunted every where for the 12v ground buss for these circuits to no avail.

Any ideas where I might look?

Thanks for any help given.

 

[seraby22]

........Update.......

I have two circuits for 12v interior lights, the second one all lights work fine