power mirror relay setup

I've built a circuit that will do mirrors up and down with only two relays.  You would be able to do left and right with two more relays.

The trick is to use DPDT relays.  You'll end up with one relay for every position.  You could also do it with SPDT relays, as long as you have all the wires rest at ground.

Depending on the motor in the mirror you may be able to skip the relays and go with transistors.  You would need, I'm guessing, 3A transistors on the output.  The overall circuit would be pretty complicated (well, more busy then complicated) and would probably end up taking up more room then a bunch of small DPDT 3A relays.  The nice thing about the relays is that you can drive them directly from a switch with no problems, and no added compoenents.  When you get in to transistors you'll have to add some resistors to bias the base/gate.

So I was thinking....

The big problem you have here is the 'common' wire between the two motors.  This prevents you from running a simple 5 wire setup.

Recently, I bought a mirror control switch off of Ebay for ~$5 that is out of an Infiniti G35 coupe.  The switch is completely setup to run mirrors of your configuration without ANY relays at all.  The switch, at rest, leaves all wires disconnected, and when used for each direction switchs both sides of the correct motor. 

So, if I were you, I would look for a switch that is setup like this and skip building a controller!

Well, with a DPDT relay you'll need a circuit board to mount it on, as I've never seen an automotive DPDT type relay.

The digram would be pretty simple, one relay for each direction.

A DPDT relay is essentially two sets of isolated contacts with one coil.  You run your + voltage to one mirror wire through one contact and your - to the other corresponding mirror wire. 

This will leave you with nothing connected during rest, and when each individual relay is energized the mirror will move.  You may want to throw a safety in there to prevent a left/right and an up/down at the same time, as it may blow the fuse.