Dash switch relay wiring (geekyness warning)
 

Observed fact: OEM dash switches, like those for the heated seats as an example, are momentary switches that require a relay that can latch on/off to do their work.

[IMG]http://www.****************************************************.com/mm5/graphics/00000001/986DEFSWITCH.jpg[/IMG]

Question: how about an OEM momentary switch combined with a 12V latching relay to allow a push of the switch to set an on-state or off-state of a piece of equipment (vacuum solenoid valves on a sport exhaust on/off in my case.)

It appears that something like this would work great. Electrical gurus, have at it!