Thanks for that latching relay. it's interesting and I'll have to study that more.

What I'm working with, in simple terms, is a switch to activate the circuit. I cannot change this switch. It changes polarity to the fan location with each activation. I also have a motor in the fan for the fan lid that is DC and can reverse direction on polarity for the up and down action. And I have two limit switches at the fan lid that are NC until the lid opens them. I can wire it any way that is necessary, but that is all I'm working with, so far. The fan motor is a separate circuit and not involved in this.

 

Are there four wires coming from the switch as you showed in your diagram?

 

Are there four wires coming from the switch as you showed in your diagram?

I will make you a new diagram.

 

Is the 12V connection to power to the switch available?

 

Is the 12V connection to power to the switch available?

No. the fan lid switch is remotely located from the roof fan. I do not have access to modifying this switch as it is handled through a remote Plex Panel for it's logic. There is 12V @ the fan AND a lid motor connection of + -. I am only concerned with the lid motor. In a nutshell, there are four wires going to the roof fan. Two are DC for the fan motor which blows air. That is good. The other two are for the lid motor which is all I'm concerned about. There are two different coach buttons. One is for the lid that provides a positive or negative voltage to operate the lid up/down. The other button is an on off for the fan motor that blows air. If this was simple, I could have done it easily. But it's turning out to be complicated due to the operating switch that flips polarity on each press/activation.

 

One is for the lid that provides a positive or negative voltage to operate the lid up/down.

Okay, one last confusion.
Why do you say it's a negative voltage? Have you measured it?
Where is that coming from, since you only have a positive battery supply available.

 

Okay, one last confusion.
Why do you say it's a negative voltage? Have you measured it?
Where is that coming from, since you only have a positive battery supply available.

In the plex device panel, which actually operates the circuits, there must be a dpdt set up that reverses polarity of the circuit. Each time you push the switch to the fan lid, it changes polarity and raises it or lowers it. The way the rv is built is-no switch controls any dc circuit. It sends a signal to the plex panel that operates the logic of all the dc circuits. This is why I cannot modify the switch. It's just Cat V to the Plex Panel. I can only modify the circuit at the fan.

 

In the plex device panel, which actually operates the circuits, there must be a dpdt set up that reverses polarity of the circuit. Each time you push the switch to the fan lid, it changes polarity and raises it or lowers it. The way the rv is built is-no switch controls any dc circuit. It sends a signal to the plex panel that operates the logic of all the dc circuits. This is why I cannot modify the switch. It's just Cat V to the Plex Panel. I can only modify the circuit at the fan.

I understand that but my confusion is still what you mean by "reversing polarity", as no negative voltage is available.
It would seem that the either signal to the lid can be either a plus polarity voltage or zero.

 

 

Okay, but in all cases the (-) polarity must be ground, it's not plus and minus voltages.
That's a significant distinction.

So tell me again what signals EXACTLY, do you need to the lid motor from the Plex Panel signals.
I may be a little dense, but I haven't been able to clearly differentiate between what you have and what you want.
In other words, for each of the two signals from the Plex Panel, exactly what signals do you want going to the lid motor.
And please don't use the + and - terminology, use + and ground, since that's the only two signal levels you have.

 

Okay, but in all cases the (-) polarity must be ground, it's not plus and minus voltages.
That's a significant distinction.

Ok, Ground.. It's a ground to the chassis and battery. I don't think this can be done. Thank you for your input.

 

Ok, Ground.. It's a ground to the chassis and battery. I don't think this can be done. Thank you for your input.

I think it can be as it's not that complicated.
I just need to understand what you exactly need, which should not be that difficult to explain (apparently you think you have).

So are we through here?

 

I think it can be as it's not that complicated.
I just need to understand what you exactly need, which should not be that difficult to explain (apparently you think you have).

So are we through here?

I don't know exactly how to communicate it. I need the plex output that is + on one leg or the other let to split into two circuits to the fan that have limit switches in them. So when you push the button once it's on one circuit and on the second push it switches to the other circuit that has the closed limit switch and will operate the lid in the opposite direction.

 

Okay, thanks for further clarification.
Based on my understanding now, I think a latching relay such as this should work.
Below is the relay the connection diagram:
Solder the coil terminals 1 and 2 to ground.
Solder coil terminal 9 to one of the Plex outputs, and terminal 10 to the other Plex output.
Solder pin 4 to the +12V.
Solder pin 3 to one of the lids limit switch connections, and pin 5 to the other lid connection.

You would also need to connect a small diode (such as a 1N4148) between pin 9 (cathode) and pin2, and between pin 10 (cathode) and pin 1, to protect the Plex output from any spikes from the coil inductance.

Thus the alternate + signals from the Plex output will latch the relay in one direction and then the other, connecting + power alternately to the two lids limit switch connections.

Does that seem like it will work?

Have you had any experience soldering?



Alternately you could use a latching relay on a PCB such as this, but you would have to reverse the two coil protection diodes on the board, to operate from the polarity of the Plex signals.

 

Here's another idea...

https://www.amazon.com/Forward-Reve...12v+latching+relay&qid=1710696418&sr=8-8&th=1

Connect one lid motor wire to forward and one to reverse. Since you will always have one wire '+' and one wire '-' depending on the direction the wire that is positive will select the direction and since the other is "grounded" it won't have any affect.

I wish I would have put a little more effort into it from the beginning. I would have though reverse polarity would have been easy enough to understand.

 

Connect one lid motor wire to forward and one to reverse.

Note that the switch signal is momentary not steady.

 

Here is my understanding of the circuit. I'm retrofitting an RV fan Lid switch to work with a newer fan that is wired different than the original. I cannot change the switching to the fan (the reversing polarity to the fan to operate the lid up/down) so this is what I have to work with. My problem is the limit switches that need to cut the circuit when the lid is down or all the way up.

Use the circuit which I have published here quite a few times, it uses two SPDT relays, you can use the same wiring as you have now. The full up limit switch will open the up relay, the full closed limit switch will open the down relay.

 

Note that the switch signal is momentary not steady.

The switch signal yes... the power to the motor after the plex panel no. That would be the place to connect such a device.

 

I thought I would draw out what @MisterBill2 proposed for a visual. I was somehow under the impression the limit switches were not accessible. If that is the case then obviously it won't work, but if they are accessible then honestly this probably the simplest way to go about it. My apologies for the hand drawn diagram, but it takes me entirely way too long to draw anything in software.



@crutschow my apologies for any rudeness. I know at times people overthink things and get tripped up over details. Since this post is in an automotive environment and some form of actuator I assumed '+' and '-' to be standard automotive markings and nothing more.

 

The hand drawing is much clearer than some others, and there is no question as to how the circuit shown will work. So no apology needed at all.
Note that the limit switches must be wired so that they are closed, except at the desired stopping point. AND, with this arrangement the motor will stop much more quickly when the relay releases. Quite a handy feature if you need it.