Reverse polarity relays for linear actuator.

I am wiring up my retractable liscense plate. I want to use the channels from my shaved door kit to raise and lower it (no switch). I have a couple of diagrams to do this, but I don't understand any of them. The one I found on the internet said to use two relays, run (+)12v constant to the 87,86 terminals of one and 87,85 of the other, then run the (-) remote outputs to 86 on one and 85 on the other, then connect the wires of the motor to the 30 terminals. However, it then says to to connect the middle terminals (87a) to ground... but they are hot!

Has anyone ever tried this, or do you even know what I am talking about. If I can't figure out how to do this with only 2 relays, I think I can get it to work with 4, but I've heard that it can be done with only two.

Never mind, even if it can be done with two, I don't want to hear about it, becuase I just did it with four. It works.

sounds too complicated, why dont you just run it on a switch?

It can be done with 2 and you have the correct instructions. 87a should not be hot unless you have 30 hooked to hot.

Originally posted by MadMatt

but I don't understand any of them. The one I found on the internet said to use two relays, run (+)12v constant to the 87,86 terminals of one and 87,85 of the other, then run the (-) remote outputs to 86 on one and 85 on the other, then connect the wires of the motor to the 30 terminals. However, it then says to to connect the middle terminals (87a) to ground... but they are hot!



no, they are not. The diagram is right. It is what is called a "rested ground" relay. Unless the relay is energized, there is ground, supplied by 87a, on each motor wire on 30. When you energize the relay (12v on one of 85 or 86 and ground on the other) you "break the ground" from 87a and connect 87 to 30.

This way you can keep the ground on the wire you dont need and 12v on the wire you do need and get reversing action. Its the same way power windows work, only they use special switches that do the same thing.

I'm sure I had everything hooked up right, and 12v was comming from 87a. I got it working though with 4 relays, and I already got the wires cut and hooked up. I'll post some pics when I get everything together. I made a whole new front bed panel out of 1X2 tube, and it looks pretty clean. I used a 6" Warn actuator that I got on Ebay for $40, and I made my own rail system.

Originally posted by MadMatt



I'm sure I had everything hooked up right, and 12v was comming from 87a. I got it working though with 4 relays, and I already got the wires cut and hooked up. I'll post some pics when I get everything together. I made a whole new front bed panel out of 1X2 tube, and it looks pretty clean. I used a 6" Warn actuator that I got on Ebay for $40, and I made my own rail system.

there is a difference between an abscence of ground and 12v, even though they read the same on a voltmeter. There is no currrent on 87a, it is only connected to 30 until the realy is energized, then it is disconnected from everything while 87 is connected to 30.