12v lamps go dim, then bright repeatedly

converter going bad.

loose connections on your converter

Another possibility is a auto resetting thermal circuit breaker on another circuit tripping & resetting. Do you have any other 12V device that has stopped working? If you have a clamp on DC amp meter, check the battery current. If it goes up when the lights dim, that is likely the problem.

Most converters don't show problems, just go kaput but we had one do the same thing. Just look at the Amperage and style for a replacement. You most likely won't find an exact replacement but it needs to be the same size or a higher amperage by maybe 10 AMPS to replace the old one. It just has to fit in the same place. They are easy to put in, the difficulty being in where it is placed but can be done with a screwdriver. Ours was $65 and took 10 minutes in an Arctic Fox TT. You can pay $250 for a repair facility to do it but all you do is hook Red to Positive, White to ground, copper to the ground wire (usually bare) and plug it in.

I would measure some DC battery voltages. A fully charged battery setup should read around 12.6-7VDC without the shore power connected.

The on-board converter/charger when connected to shore power should be putting out a steady 13.6VDC unless it is doing its smart mode events. My DC output from my on-board converter/charger unit can read 13.2VDC, 13.6VDC, and 14.4VDC depending what mode it is in at the time. Other brand converters/chargers may put out 15VDC for about 15 minutes every 21 hours doing what they call a desulf mode.

Sometimes a shorted cell in your battery setup will really work on your converter/charger unit trying to overcome the shorted cell status. This usually ends up getting your batteries very hot and they may boil out battery fluids.

This is not normal for your 12VDC system to be doing this... Batteries and the on-board converter/charger will be suspect items.

Roy Ken

loose ground in one of the lights. Is it all or just the overhead lights.

Bad converter.

2oldman wrote:
converter going bad.

I have to agree, mine did the very same thing. Your RV is more than 10 years old and if it hasn't been replaced then it probably has the same old WFCO that Fleetwood put in all their RVs.

When I replaced it with a Progressive Dynamics converter the problem went away.

I opened up my old one and there was a few burnt components in it.

Take a look at it and post what it is here, and someone here may be able to help you pick a good replacement.

Absolute classic sign of a failing converter.

My 5th doing the same exact thing! Time to change the WFCO thinking PD, I have the WFCO 8955, what is the best PD model to change to? Thanks