Dimmer switch

[1carguy]

I have a Jayco Eagle HT FW that has 6 ceiling mounted main lights. When turned on these are super bright and way too much light. I wish the 2 lights in the hall were on a separate switch but they aren't and I'm not willing to tear apart ceiling and wall panels to access the wiring to rewire these on a separate circuit.

So, another alternative is to install a dimmer. Seems that all the 12V dimmer switches I've seen are 3 wires. The switch that controls the lights now are only 2 wire switches. I'm assuming that the 3 wire dimmers need a separate ground. If I'm correct, that means I would have to try to fish a wire through the wall and find a ground somewhere. Am I correct in thinking this? Any easier solutions?
This is the dimmer looking at:

 

[Gary RV_Wizard]

There are two types of dimmers, resistance and pulse-width modulated (PWM), The simple resistance type goes inline with the +12v feed and has two wires. PWM has to be wired to both +12v and ground (12v-).  You don't see the simple 2-wire types as much anymore because LEDs generally don't work well with them (LEDs are very voltage sensitive). I strongly recommend using the PWM 3 or 4 wire) type if you have LED lighting or may change over to it in the future.


Assuming you don't have LED lighting. here's are a few that would probably work for you without requiring a ground wire.
https://www.ebay.com/itm/Dimmer-Switch-12-volt-on-off-Light-RV-Motor-Home-Camper-Travel-Trailer-Marine-Br-/391283790553
https://www.ebay.com/itm/RV-CAMPER-TRAILER-ELECTRONIC-DIMMER-CONTROL-SWITCH-BY-COLE-OF-BOSTON-/122197851727
https://www.ebay.com/itm/Dimmer-Switch-RV-Boat-Camper-Interior-Led-Ceiling-Light-Rotary-Switch-Panel-/202537687053

 

[1carguy]

Thanks for the reply Gary. If I can run a ground wire easily, I'll go that route. If I have to tear everything apart, I try one of the switches you linked to. I'm pretty sure the 6 lights in the ceiling are LED, but I haven't popped off one of the lens to make sure.
thanks again....

 

[grashley]

In case you do not know, ground locations are not hard to find.  On my camper, the main control panel that includes switches like this is located almost directly above my power panel.  A ground connection there is easy.  Any 12 V negative works.  Also, any metal frame or chassis member works.

 

[Gary RV_Wizard]

I've probably got a 12v two-wire dimmer laying around that you could have for free, but it might cost as much to ship it to you as buying a new one locally.
As grashly noted, there must be a usable ground nearby since every 12v circuit needs one and the RV chassis & frame serves as ground for the entire system (just like a car).