Quote:
Originally Posted by wally999
Does anyone know which wire does what on the back of the PSM switch on the dash? I want to use the switch as an off and on for some driving lights.
|
Ahh! A subject I have spent a lot of time on lately. I'm not an expert but I am in the process of getting parts and wiring up some stock switches, so maybe I can help. Almost all the Porsche dash switches with an LED indicator are the same. So Chuck is correct, you could also use a footwell lights switch, and as you see he posted the diagram for it.
All these switches are momentary, which means you'll need some sort of latching relay to keep your lights on after you release the switch. There are a couple good options for these relays but one I like the look of is a VW headlight relay from the RHD Beetle. Its nice because it will allow you to use an OEM dash switch as a pushbutton on-off, but when power is cut to the relay (from turning off your ignition for example) the relay resets. Meaning when you start the car the next time the lights are automatically in an "off" state. See this link and scroll down the page to "434 relay."
Graeme's Webspace
If you want the lights to "remember" the last position you left them in you'll need a relay that stays latched even when you turn off the main power feeding it. That shouldn't mean the lights will stay on when you turn off the car, but if you wire it right they will come on again with the key if you had them on when you shut off the car. This is the relay I have ordered to control my homemade sports exhaust, so it will remember the last position I left it in, on or off. (At least I think so, the part should be here in a day or two and I can report back.)
12V latching relay | changeover latching | 12V 25A latch relay
Finally, if you want to light up the LED on the switch when your lights are on, you'll have to supply that LED a negative connection when the circuit is active. Having a separate relay that trips and supplies ground to the LED when the switch is pressed is one way to do it and probably easiest since your main latching relay will be switching +12V.
The OEM switches are easy to get hold of, so no need to use your PSM switch unless you have an extra...
Good luck
