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Old 01-20-2022, 02:12 PM   #1
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THOR #18162
LED dimmers

The main living overhead LED’s in my 2020 Thor outlaw are too bright and I’m looking to add a dimmer control.

The switch only has a wire in and out so I am thinking one is a 12v hot and the other is going to the light. In the YouTube below the owner connected a three wire dimmer to a similar two wire switch. They also sell a small switch cover plate that adapts the dimmer to fit the switch plate. Though I’m not sure that would fit a Thor panel.
Has anyone done this on a Thor.


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Old 01-20-2022, 02:49 PM   #2
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Don't you have two switches for the interior lights (3-way)? Not sure if that might throw a wrench in the plan. Also, not all LEDs are dimmable.
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Old 01-20-2022, 03:34 PM   #3
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Originally Posted by 16ACE27 View Post
Don't you have two switches for the interior lights (3-way)? Not sure if that might through a wrench in the plan. Also, not all LEDs are dimmable.
No there is only one switch to turn on the lights. I guess I could try wiring a dimmer to see if it works. But some switch’s are wired on the negative side to turn the lights on. So I will have to check my wiring. I’m not sure if the grand design is negative side or positive wired in the video.
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Old 01-20-2022, 04:53 PM   #4
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Without getting deep into the weeds on technicalities, LEDs themselves are all dimmable... it's when they are driven by an AC to DC conversion circuit that problems happen - like with the screw-in replacement bulbs for household (AC power) use. But those are generally NOT used in today's RVs... nearly ALL RV lighting today is powered by DC current

LEDs in your motorhome work on DC current, so dimming is simply a matter of reducing that current by using a variable resistor (or potentiometer), the knob control, to lower the current going to the LED.

There should be three wires/contacts on the variable resistor control: 12v DC in, Ground, and DC out - which is the line with the reduced current. Your existing "on/off" switch simply breaks the circuit - BUT it may be wired into the ground, not the 12v positive. So key is figuring out which wire is "hot", and which is ground using a multimeter. Then hook the wires to your dimmer as described above.
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Old 01-20-2022, 05:10 PM   #5
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Originally Posted by Chateau_Nomad View Post
Without getting deep into the weeds on technicalities, LEDs themselves are all dimmable... it's when they are driven by an AC to DC conversion circuit that problems happen - like with the screw-in replacement bulbs for household (AC power) use. But those are generally NOT used in today's RVs... nearly ALL RV lighting today is powered by DC current

LEDs in your motorhome work on DC current, so dimming is simply a matter of reducing that current by using a variable resistor (or potentiometer), the knob control, to lower the current going to the LED.

There should be three wires/contacts on the variable resistor control: 12v DC in, Ground, and DC out - which is the line with the reduced current. Your existing "on/off" switch simply breaks the circuit - BUT it may be wired into the ground, not the 12v positive. So key is figuring out which wire is "hot", and which is ground using a multimeter. Then hook the wires to your dimmer as described above.
Yes so there is only two wires. So it may not have a ground wire in there. But I’ll have to check if it’s a ground switch. But I would think it’s a 12v hot wire type. Curious does anyone know off hand. If there is no ground wire do I need to go to the battery or look around for a ground. I’m not sure if the Grand Design is the same as they did it in the video.
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Old 01-20-2022, 05:33 PM   #6
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If you know how to use a multimeter, check if one of those two purple wires going to the switch is +12 volts. It will either be +12 volts or ground (no current). Then the other one will go to the lights.

If no current is found at the switch, they likely ran 12 volt power directly to the lights; putting the switch in the ground wire... which makes wiring a dimmer, while not impossible, more of a pain. You can check that by popping off a cover on one of the lights that the switch controls.

If those purple switch wires aren't carrying 12 volts DC, wiring a dimmer into that switch (like in the video) won't work. You'll have to do some rewiring - which could get more involved if you're not comfortable with - and understand - 12 volt circuit wiring.
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Old 01-20-2022, 07:28 PM   #7
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Originally Posted by Chateau_Nomad View Post
If you know how to use a multimeter, check if one of those two purple wires going to the switch is +12 volts. It will either be +12 volts or ground (no current). Then the other one will go to the lights.

If no current is found at the switch, they likely ran 12 volt power directly to the lights; putting the switch in the ground wire... which makes wiring a dimmer, while not impossible, more of a pain. You can check that by popping off a cover on one of the lights that the switch controls.

If those purple switch wires aren't carrying 12 volts DC, wiring a dimmer into that switch (like in the video) won't work. You'll have to do some rewiring - which could get more involved if you're not comfortable with - and understand - 12 volt circuit wiring.
Ok I checked and there is no current. So it looks like they ran 12v direct to the lights and are breaking the ground at the light switch. I’m not sure what to do in that case. Could or would the dimmer go next to the first light that has the incoming 12v power.

The problem with trying to run wires from the switch is it is located on the side wall of the sink and the lights are on the ceiling.
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Old 01-20-2022, 08:10 PM   #8
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Wait.
Was switch off or on ?
Did you try both sides/ends of the switch?
Did you check the meter against a known good 12v source?
Did the meter read correctly when you checked the known good source?
Where did you ground the other lead?
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Old 01-20-2022, 08:36 PM   #9
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Originally Posted by ducksface View Post
Wait.
Was switch off or on ?
Did you try both sides/ends of the switch?
Did you check the meter against a known good 12v source?
Did the meter read correctly when you checked the known good source?
Where did you ground the other lead?
Maybe I should check it again because I read a switched negative on lights is rare. But I checked the solar controller below and it read 12.6 V then I checked both sides of the light switch for power. One lead on the negative of the solar to the battery and the other to the switch both sides. The switch was on at the time I think.
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Old 01-20-2022, 09:28 PM   #10
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If you have a working solar charge controller nearby - and it's ground terminal is directly wired to the negative battery post, you should have confidence in that as a good ground source.

Turn the switch ON... verify it's in fact ON (and current flowing) by the ceiling lights being on. Then CAREFULLY touch the meter negative lead to the charge controller negative terminal... touch the meter positive to either of the switch contacts.

If you DO NOT get +12 volts, the switch is wired with the ground wire. If you DO get +12 volts, your job just got a LOT easier... you can just wire in the dimmer.

A possible caveat: If there's another switch that controls the SAME lights, you likely have a three-way switch combination. But it appears that yours is just a single switch... with only two wires. So I'm assuming NO 3-way switch.

Regardless of the switch, pop a cover off one of the ceiling puck lights. Are the wires soldered? Crimped? Or just plugged in with connectors? Usually all the lights in the ceiling are strung together in parallel and work from a single switch.

If in fact your switch is using a ground wire, you'll either have to fish a power wire from the switch to ONE of the parallel lights... OR use another "creative" method - IF YOU TRUST YOUR SKILLS!

You can "convert" that existing ground wire to a powered wire... BUT you must reverse the wiring on the first light, AND find another nearby ground source. See where I'm going with this? LEDs are diodes, which are polarity sensitive... they won't work with positive/negative switched.

The dimmer switch can be put anywhere in the 12 volt feed wire powering the lights. But you have to make sure that you tap in close to the lights so as not to interfere with any other lights/devices which may be on that same circuit.

It's really not that complicated if you think it through - AND mark things as you go.
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Old 01-20-2022, 10:05 PM   #11
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Quote:
Originally Posted by Chateau_Nomad View Post
If you have a working solar charge controller nearby - and it's ground terminal is directly wired to the negative battery post, you should have confidence in that as a good ground source.

Turn the switch ON... verify it's in fact ON (and current flowing) by the ceiling lights being on. Then CAREFULLY touch the meter negative lead to the charge controller negative terminal... touch the meter positive to either of the switch contacts.

If you DO NOT get +12 volts, the switch is wired with the ground wire. If you DO get +12 volts, your job just got a LOT easier... you can just wire in the dimmer.

A possible caveat: If there's another switch that controls the SAME lights, you likely have a three-way switch combination. But it appears that yours is just a single switch... with only two wires. So I'm assuming NO 3-way switch.

Regardless of the switch, pop a cover off one of the ceiling puck lights. Are the wires soldered? Crimped? Or just plugged in with connectors? Usually all the lights in the ceiling are strung together in parallel and work from a single switch.

If in fact your switch is using a ground wire, you'll either have to fish a power wire from the switch to ONE of the parallel lights... OR use another "creative" method - IF YOU TRUST YOUR SKILLS!

You can "convert" that existing ground wire to a powered wire... BUT you must reverse the wiring on the first light, AND find another nearby ground source. See where I'm going with this? LEDs are diodes, which are polarity sensitive... they won't work with positive/negative switched.

The dimmer switch can be put anywhere in the 12 volt feed wire powering the lights. But you have to make sure that you tap in close to the lights so as not to interfere with any other lights/devices which may be on that same circuit.

It's really not that complicated if you think it through - AND mark things as you go.

Nice good info. I was thinking the easiest way if it’s a negative switch would be find the incoming hot wire to the ceiling lights. Then fish through the light hole to the wall cabinets and put the switch underneath a cabinet.
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Old 01-20-2022, 10:21 PM   #12
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Ok I checked and there is no current. So it looks like they ran 12v direct to the lights and are breaking the ground at the light switch. I’m not sure what to do in that case. Could or would the dimmer go next to the first light that has the incoming 12v power.

The problem with trying to run wires from the switch is it is located on the side wall of the sink and the lights are on the ceiling.
So what difference does it make? You're taking a rheostat (3 wires) and turning it into a variable resistor by shorting two leads. The voltage drop will be the same whether the variable resistor is in series before or after the LEDs, on either the positive or negative battery leg. What am I missing?
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Old 01-21-2022, 12:34 AM   #13
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Originally Posted by 16ACE27 View Post
So what difference does it make? You're taking a rheostat (3 wires) and turning it into a variable resistor by shorting two leads. The voltage drop will be the same whether the variable resistor is in series before or after the LEDs, on either the positive or negative battery leg. What am I missing?
Ah I’m not the wiring expert. So hopefully I can use the same three wire dimmer switch on the negative leads coming from the light switch. That would make it easier to wire from the switch.
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Old 01-21-2022, 12:50 AM   #14
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Can you swap in Bluetooth controlled bulbs?
Bazillion color light, dimmer, timer, auto-off, remote controller, auto-on....

https://www.amazon.com/AIBOO-Changin...60888959&psc=1

Hundreds to choose from(inexpensive sample above)
Easier than what you're trying now.


Maybe, doubtfully, theoretically, impossibly controllable by the thor system....
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Old 01-21-2022, 01:51 AM   #15
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To complicate things a little more here's a good read about dimmers specifically for RVs. Note the references to "high side" and "low side" type dimmers. This gets a little technical discussing PWM dimming methods and possible RF interference (buzzing noise) on radio and TV audio. But stuff to be aware of.

RV Dimmer Wiring Options.

So, regardless of the switch wiring, seems as though there's a solution for every scenario. Just be aware of potential drawbacks and gotchas.

Me? I'd pick out one and try it... either it works or it doesn't. Return it and try option #2!
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Old 01-22-2022, 12:03 AM   #16
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Ok good news for anyone doing a dimmer in a similar Thor set up. I found the plus and minus wires in the first closest LED overhead light I took off. Then I opened the wall cabinet and found the same plus and minus wires going from the switch to the lights. So now I have a plus and minus and can likely fit a dimmer next to the cabinet door or the bottom of the cabinet. The white wire is the plus and the purple negative. Now to find a dimmer I can get in there.
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Old 01-22-2022, 12:12 AM   #17
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https://www.thorforums.com/forums/f4...ays-20421.html
This will fix your pictures.

Thanks for the follow through on your installation.
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Old 01-22-2022, 12:30 AM   #18
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Originally Posted by ducksface View Post
https://www.thorforums.com/forums/f4...ays-20421.html
This will fix your pictures.

Thanks for the follow through on your installation.
Thank you pictures fixed.
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Old 01-26-2022, 08:11 PM   #19
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Originally Posted by Snks View Post
The main living overhead LED’s in my 2020 Thor outlaw are too bright and I’m looking to add a dimmer control.

The switch only has a wire in and out so I am thinking one is a 12v hot and the other is going to the light. In the YouTube below the owner connected a three wire dimmer to a similar two wire switch. They also sell a small switch cover plate that adapts the dimmer to fit the switch plate. Though I’m not sure that would fit a Thor panel.
Has anyone done this on a Thor.


You have tried to hold light button, most after 2018 dims by holding button
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Old 01-26-2022, 09:45 PM   #20
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You have tried to hold light button, most after 2018 dims by holding button
It only has a toggle type of switch either the switch is flipped up to on or down to off and it’s switching the negative wire. So I don’t see any way it could dim.
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