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?

[bdstone914]

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?

I should have one hiding somewhere amoungest my plethora of parts. It should meet or exceed your patina requirements.

[Montreal914]

If Bruce doesn’t find his, I have one.

[Superhawk996]

Thanks guys!

Bruce incoming PM

[gtbarnes]

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?

I should have one hiding somewhere amoungest my plethora of parts. It should meet or exceed your patina requirements.

Is there a reproduction/oem lens available for that, with the white letters?

[JeffBowlsby]

To be sure you get what you need, the 1972-73 are 4-pole, the 1974-76 are two pole. So "73 or later" covers both types. The 4-pole has an IC and circuitry in addition to the bulb, the 2-pole is just a light bulb.

Sounds like you need a '72 or '73, not the 2-pole version. Which do you need?

[bdstone914]

@Superhawk996

date='Mar 5 2025, 01:01 PM' post='3194909']
Thanks guys!

Bruce incoming PM
[/quote]

Go with the one Eric has. I was thinking of another part.

[Superhawk996]

To be sure you get what you need, the 1972-73 are 4-pole, the 1974-76 are two pole. So "73 or later" covers both types. The 4-pole has an IC and circuitry in addition to the bulb, the 2-pole is just a light bulb.

Sounds like you need a '72 or '73, not the 2-pole version. Which do you need?

You are correct Jeff - 4 pole with a PCB stub that serves as the electrical connection. Need that for my car (73’).

Didn’t realize there were other variants after 73’ but should have (IMG:style_emoticons/default/headbang.gif)

Here is a separate question then. On later cars post 73’ where does the seat belt circuitry reside? Is that then moved under the passenger seat as part of that big relay / buzzer / module with the two yellow solenoid wires? I’m thinking that is the case.

I’d like to obtain the 74-76 version of that “module”. I knew the 74-76 current flow diagrams show the circuit differently (ie as a black box diagram) but didn’t realize it was a completely different circuit.

Need the later variant for a friends 74’ project as well.

So in guess I’m looking for two - a mid (72-73’) variant and a late black box (74-76’) I already have one of the two pole fasten seat belt lights with just the plain spade connectors (ie the 911 p/n warning light).

@JeffBowlsby Thanks for pointing this out to me.

I’ll do some more study of the late schematic and the late PET.

[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.

[Superhawk996]

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

(IMG:style_emoticons/default/pray.gif) That would be awesome

[Montreal914]

On a plane now.
Will post pictures of what I have Monday night. (IMG:style_emoticons/default/smile.gif)

[JeffBowlsby]

Cool! Interested in what you find and share with us. And the mods you propose.

So many just bypass and toss these things.

[gtbarnes]

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.

I would be interested in a nos seatbelt dash light unit, if u can sell one???

[Montreal914]

@Superhawk996 Here is what I have. I am not sure which version you want, the PCB one or the tab one. Would come with the lens shown.

Let me know (IMG:style_emoticons/default/beerchug.gif)

[Superhawk996]

@Superhawk996 Here is what I have. I am not sure which version you want, the PCB one or the tab one. Would come with the lens shown.

Let me know (IMG:style_emoticons/default/beerchug.gif)

@montreal914

It’s the one in the left that I need for the 73’

Thank you so much!!