Original bathroom light (and fan) wiring schematic?

[Astrodokk]

Before I quit and order all new parts for the bathroom fan and light, I was wondering what the wiring schematic is for that fixture. I believe it was wired incorrectly, because I am able to get the fan working (bad switch), and the lights working but holding the wires different than what it was before.
Someone has been in there before and connected all 4 of the black wires (bulbs) together to the 12V power (and I got a spark), but I connected two bulbs to power and two bulbs to negative, and now they work!
Granted, no switches involved but I can order a pair for 7 bucks and see if it all works after that. I know replacing everything will be better, but as a learning experience, I'd like to finish this little project before investing into more. Also, it's fun painting those yellowed trims.

[Astrodokk]

I just ordered two waterproof switches from Amazon.

https://www.amazon.com/gp/product/B07Z6 ... UTF8&psc=1

I'll get those wired in and hope that everything works as designed originally. The wiring was a mess in the box, so I could use a little help with how to wire it, as I'm not that knowledgeable with electrical.

[caconcourse]

You can't just go by the wire color because the RV wiring uses different choices than standard wiring. In particular, the RV ground wires are generally white, not black. Positive 12V is usually red, but it can be other colors as well, including black. So you get odd combinations when connecting a fan or light for example, red to white for +12v, or white to black for ground.

You just have to measure the DC voltage to determine which supply wire is positive and which is ground. The switch would be wired in series with the hot wire to the + input to the device. The RV ground is just connected to the device ground wire (this could easily be white to black!)

[chin_k]

this is how to figure out if the wire is positive or negative for DC. Since the negative is grounded to the chassis:

1, if the wire to the chassis shows 12V+ DC, it is positive. Make sure everything is off, since it can be the negative wire coming from a low current device. For example, if you test the negative wire coming out of the light, it should show 8-12v depends on the wattage of the lamp. It is not the positive wire, obviously.

2, if the wire to the chassis shows no voltage, and it has continuity (near zero resistant) to chassis, then it is negative.

Make sure you have a fuse if you are not sure about the wiring. It is not fun to have the wiring melt somewhere you can't get to if you accidentally short the positive and negative/ground together. The fuse is to protect the wiring, by burning itself up. If in doubt, remove all the fuse except one, and replace the one you are working on with a low amp fuse, (but high enough for the device). The default fuse should be fine, but it is better to be extra careful until you are more experienced.

[Astrodokk]

I wouldn't worry about it so much if I had the wiring diagram. I'm not so sure it was wired correctly before I opened the box, as it seems someone was in there before. The only undisturbed pieces were the two permanently crimped wires coming in from the ceiling. I cut those to be able to get the fan out. I took a pic before I opened the box but forgot to get a pic after I opened it. Now I have them all loose (but labeled).
I was hoping someone had a pic of the inside of the light box. That would help immensely.
Either way, I will figure it out. Is there a way to disconnect the coach batteries from the coach? I saw a YouTube video of a Chinook with a toggle on/off switch next to the water heater and tank heater switches. I thought that was a good idea precisely for this reason.

[chin_k]

Just take the lugs off the negative terminal and the batteries will be disconnected. But if you do it under the sun, you need to make sure the solar is not sending the power directly to the coach. A regular toggle switch won't be big enough to handle the connection, so it is either one that is rated for 45A or more (I forget exactly how many amp is the resettable breaker for the LVD), or there is a solenoid that handle the current directly.

DC low voltage is pretty simple for the most part. But I did managed to bust up a few hundred dollars of equipment every once a while. Let me know if you want me to do the fan for you

[BobW9]

In general, the Store switch on the overhead in the cab is all that is required to disable all 12V power to the coach. That is its exact purpose. It triggers the LVD to not allow current to pass, and all 12V wiring into the coach should be going through the LVD. Assuming, of course, your Concourse still has the LVD it originally came with.

Yes, the solar panels have a hard-wired connection to the batteries, but if the store switch is on, there is no 12V path from the batteries to the distribution panel, so it doesn't matter that they are still charging the batteries.

[Astrodokk]

Ok, sounds good.
I'll be figuring out the bathroom lights wiring, and I don't want to burn anything up.

[Astrodokk]

Does it matter if I disconnect the negative on the coach batteries as well? I read that if the solar charger is connected to the panels, the batteries need to be connected as well.

[BobW9]

If you disconnect the negative on the batteries, make sure the store switch is on STORE, without power to the coach. I had a service tech one time who disconnected the negative while the coach was on, and it fried the LVD (the LVD manual warns that can happen).

I have, without thnking, disconnected the batteries and not had any damage to the solar charger, but that doesn't mean its a good idea. Put a heavy blanket over the solar panel, then there is no power coming in to the solar charger, and it has to be safe.