View Full Version : 2003 Ultra Supreme Electrical question

04-02-2021, 10:01 PM
This 2003 Ultra Supreme is new to me. Only 70,000 kilometers and in beautiful condition but interior overhead cabin lights and bathroom light do not work. Is there a master switch over riding the individual light switches. Where are the fuses located for the interior lights? Is there a relay controlling these lights? The bedroom lights and the side lighting over the table, sofa and kitchen counter are working. Does anyone have a wiring diagram for this coach or can anyone tell me where to purchase a wiring diagram? Thanks, Al.

04-11-2021, 09:56 AM
They are all 12vdc, and many times they are connected with the 12V source one to the other, spliced along the way. So a bad splice at the first one can take out the others. Most often there is a switch near the entrance, and one near the bed. No breakers, but you do have a fuse in the power distribution panel for the 12VDC (usually ATC type).

My suggestion; If the fuse is good, and switches appear good, pull down one of the lights and start inspecting wires / splices. One light at a time. Good luck.

04-11-2021, 10:30 AM
Different model but similar year and my overhead lights are all on wall switches so there is no need to reach up to the fixture. I have a fuse block on the front edge of the bed that has a fuse for lighting.
Good luck and enjoy the mh.

04-11-2021, 01:55 PM
Same model, only a 2005.
Main room lights are controlled by a swith at the entrance. At the entrance I have a black panel of 3 switches that control the outside light, the step, and the bin lights. About a foot away there are two separate switches (they are white) near the front of the sink cabinet that control the main overhead lights and the floor lights. Main overhead lights will not work when the switch is off.

There is a ceiling light by the shower. That light is controlled by the bathroom light. I can only turn that one on when the bathroom light is turned on.

Hope this helps.

04-11-2021, 02:00 PM
As you enter the coach There will be several switches on the wall to the left. One of these controls the overhead lights in the forward part of the coach.

05-15-2021, 02:13 PM
RVs typically have a switch by door that controls 1-2 lights at top of step entry. So as you go in, turn ON the light switch; you can turn ON/OFF at ceiling, after you enter, but when leaving or storing, turn ON at Fixture and then OFF at panel/ wall switch as you step out. This way, you can turn on a light at door before you try to step UP in the dark.