I have a fasten belt light i pulled from my 72 parts car and want to put it on my 71 dash and have it wired to come on when all other accessory lights are on. what wire (of the four options) do i need to connect to the blue/black line? Is there a relay or anything inside the unit that needs to be bypassed??

Thanks!

That's some free thinking David...

Never saw that coming. Most want to do the opposite!

Do you have the seatbelt relay installed under the passenger seat?

haha, ya I am a free spirit Rob!

I want to emphasize safety first, lol. And i really like lights. I am redoing the dash face to replace the radio section and figured while im at it i could add this light; I dont want it to beep or anything, that would be awful, just light up.

Mike, no seat belt relay installed, I dont believe '71s came with them...

Based on standard German (DIN) wiring, the brown/white is a switched ground and the black/blue is power. I have never opened one to see how it works but I think it;s just a lamp inside.

The 1970-71 cars have no such circuitry.

The 72-73 cars have a Seatbelt Warning System - 4-pole 'Fasten Seatbelt' light, seatbelt switches, pass seatpad switch, round buzzer at fusepanel. The integrated circuitry in that "Fasten Seatbelt" housing makes it more than just a light bulb holder.

The 74-76 cars have a Seatbelt Interlock System - 2-pole 'Fasten Seatbelt' light, interlock circuity/buzzer cube under pass seat, seatbelt switches, seatpad switches.

To do what you want to do, get the two pole version of the Fasten Seatbelt housing from a 74-76 car, its just a light bulb housing.