5V Trigger for 12V Relay

Dang! I found a FET circuit I drew, but it was a P-channel.... All you need is one FET per circuit - ie, instead of the relay. FETs that switch 10A - 50A or more are commonly available and sometimes cheaper than relays. (I can get ~60A MOSFETs for $2 each.) So powering a window motor is no problem. The other main component needed is a resistor to protect the FET's "Gate" (equivalent to the Base of a transistor, or coil on a relay), but you have that as part of your switch. [FYI: For transistors, the Base current determines output current so the Base resistor is critical. But FETs are a high impedance VOLTAGE input so its input resistance is NOT critical - only the Gate voltage is.] And to ensure the FET turns off, a resistor from Gate to ground - in your case probably 1k (1,000 Ohms) or above. So one resistor and one FET instead of (resistors? &) a transitor and a relay? And silent operation? And more than (say) 100,000 relay operations? The rest is implementation. I'd assume the FETs will NOT be in the console. Relays when used are usually in the doors etc so that only one pair of heavy wires are needed (+12V & gnd). The same would apply to the FETs. But the FETs might require a small capacitor or something to filter out any noise from the console to the FET gate. Then again, a FET Gate may need a few volts to turn on.... What voltages can internal transmitters, GSMs, audio and switching produce in "other" wires? Just find a nice cheap local N-Channel MOSFET that handles the motors (ie - max current - eg, when jammed etc), but consider the biggies like 50A - they are still much smaller than relays. We can take it from there if interested.... (Dang! Another drawing....)

This is all running around in circles! The quick cheap and effective answer (no relays required) would be to get some illuminated Spal switches!

Yes Howie, but the customer.... lol - But I agree. However if people are keen to match the normally incompatible.... (At least this isn't like after market 2nd hand EFI/ECUs where people buy some ECU configuration and rather than pay for a re-config, modify their hardware (ie, distributor or sensors) at often greater expense only to end up with unique hardware!) The bummer here was the time to realise it's a series-resistor switch. That was the circling! I reckon that switch is perfect for FETs which are cheaper, smaller, quieter and last longer than relays, and can almost be used directly with no other components - maybe not even the turn-off resistor. But FET and relay, or worse still - transistor with relay (though without may not be too bad).... not me.