I got some oem switches and I want to mod them into light switches.

Here is my situation:

I would like to use the oem switch since it has illumination and button that matches the car.I have already located the illuminations and found out the switch is momentary.

I'd want them to operated as on/off switches. Here is the diagram for the lights and the included switch: https://dl.dropboxusercontent.com/u/6569565/Forester/2014-12-09%20201.jpg

The momentary switch has 2 wires, but the included switch has 3, + - and ground.

So far I've found latch relay and ic jk flip flop would work, but they are too complex (I can't seem to find the right diagram for my needs). Are there any pre made relay for my purpose, 12v?

Edit by Kamil:

I've found this one on the net, but it's for 5V: link

and can someone list the parts that are in this circuit?

Mainly the spec for the jk flipflop? For 12v tho.

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    – Kamil
    Dec 12, 2014 at 1:06

1 Answer 1


This does not use a relay but a FET, seems to tolerate your voltage needs (from 4.5V to 20V). You have to check if 10A max is ok for your application.


If you bypass the push button with your momentary switch you should have what you need.

  • \$\begingroup\$ Thank you for your answer, but I think I am still a little confused. my original wire harness has a positive negative and a ground, so If I add this to my assembly, how would I connect the ground because there are 2? Do I connect both to the same ground? I see there are 2 V in and V out. Do I just use one? \$\endgroup\$
    – ken
    Dec 12, 2014 at 17:32

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