WTB Fasten Seat Belt Light components, Need Cheap - Not Pretty - nonfunctional OK Options

[Superhawk996]

Need a fasten seat belt warning lamp assembly (housing, lens, circuit card connection)

OK if lens is faded, scratched, white lettering unreadable, etc.

Whatcha’ got?

[JeffBowlsby]

SH, I think you understand the conceptual layout of the two systems. Review the schematics for the basic layout.

The 72-73 is a seatbelt warning system. The logic board is in the dash light, it must be very simple. I think it only senses the drivers seat pad, seat belt receiver and both door switches. Buzzer is on the fuse block panel.

The 74-76 is a seatbelt interlock system. The logic board is under the pass seat, with its separate buzzer (integrated by wires). It senses both seat pads, seatbelt receivers and door switches. And locks the ignition circuits if the seatbelts are not clicked in.

Ask around, surely someone here has one or both of these.

Maybe you can reverse engineer these to figure out how they work!

[Superhawk996]

Maybe you can reverse engineer these to figure out how they work!

(IMG:style_emoticons/default/happy11.gif) Sort of working on that right now to get systems to operate / modify.

Have the 73 figured out - super simple: 1 NPN transistor, 3 diodes, and 3 resistors. Basically want a part I can play around with for some component substitutions; thus the request for crappy appearance / cheap parts. The component schematic is in Haynes (but missing a diode) and I have most of the component values from visual inspection of my 1 good part but the diodes are an unknown visually. I suspect a standard 1N4001 will work but don’t want to mess with my 1 functional part from my car.

After looking at schematic for 74+ I now realize the seat belt circuit is part of the infamous “interlock relay”. Exactly as you stated! Part number vw 133919439. Looks like earlier parts were in a metal case (pic below) and maybe later parts switched to a plastic case.

If anyone has one of these interlock relays (functional or not) and is willing to part with it, let me know. Probably prefer plastic case (easier to open) and non-functional since it looks like fair market price is about $40 for an operational part. Would rather repair a cheap non-functional part.



I will put up an overview of how they operate and component substitutions once I have these proven out and functional on both 72-73 and late 74-76’s.

@jeffbowlsby
@montreal914
@bdstone914

[bdstone914]

Maybe you can reverse engineer these to figure out how they work!

(IMG:style_emoticons/default/happy11.gif) Sort of working on that right now to get systems to operate / modify.

Have the 73 figured out - super simple: 1 NPN transistor, 3 diodes, and 3 resistors. Basically want a part I can play around with for some component substitutions; thus the request for crappy appearance / cheap parts. The component schematic is in Haynes (but missing a diode) and I have most of the component values from visual inspection of my 1 good part but the diodes are an unknown visually. I suspect a standard 1N4001 will work but don’t want to mess with my 1 functional part from my car.

After looking at schematic for 74+ I now realize the seat belt circuit is part of the infamous “interlock relay”. Exactly as you stated! Part number vw 133919439. Looks like earlier parts were in a metal case (pic below) and maybe later parts switched to a plastic case.

If anyone has one of these interlock relays (functional or not) and is willing to part with it, let me know. Probably prefer plastic case (easier to open) and non-functional since it looks like fair market price is about $40 for an operational part. Would rather repair a cheap non-functional part.



I will put up an overview of how they operate and component substitutions once I have these proven out and functional on both 72-73 and late 74-76’s.

@jeffbowlsby
@montreal914
@bdstone914

I am sure i have at least one good interlock relay. Maybe up to five and maybe a NOS.
Free to good home. NO rehoming fee.
I think you PMd your address

And on the seat belt light I will have three NOS ones in about 3 weeks. Can lend one of those.
I have never seen a metal case one.