[ghjedi]

My 1966 mustang coupe has the seat belt warning light installed under the dashboard and I'm trying to find a replacement light bulb. I believe it is a special bulb that goes off after heating up, but I could be mistaken. Does anyone know where I can find one? Or does anyone know what the bulb type or number is?

[Ivy66GT]

I can't say what bulb number it uses since mine has never burned out and its also not listed in the Ford shop manual like almost all the other bulbs. Its probably an 1895 or something similar which are $0.75 at Virginia Classic Mustang. Whatever number it is, the bulb does NOT cause it to go out after 10 seconds. That is a special seat belt light widget somewhere under the dash.

Take the bulb out of yours and see what number is printed on the side of it.

[ghjedi]

Thanks for the tip. I thought it was a special bulb, so given that the new bulb stays on all the time, I've got another issue here. Any thoughts on what might cause the light to stay on all the time? It used to work so well (turned off after a minute or 2 upon startup)

[67ragtopStang]

A relay is what causes the light to to go out after several seconds. On my '67', it was attached to a wiper motor bolt.

Just follow the wire back to the relay.

[jdstefan22]

The bulb is dependant on when your car was built. Pre 9/6/66, use 1895, post 9/6/66 use bulb 1445.

Now, for the relay. There is not a repro part available that I have found yet for this. Unless you buy the total repro seat belt warning light setup, which does not use the relay, you will need to ebay or someother thing to find an NOS relay. I found on fairly easily on ebay.

If this is your problem, to change out the relay is simple, take out the gauge cluster and you will find the relay bolted to something. When it normally is working, it stays on a short time after the car is started.

The bulb itself is responding to the relay-which is getting an electrical signal after ignition. The relay internals move over the 30 seconds or so, until it breaks the connection to allow the light to illuminate, the connection is broken, the bulb goes off, until you start the car the next time, that is basically how it works.

Of course, all of this has nothing to do with your seat belt being actually on or anything, but it is cool to have nonetheless!

[Ivy66GT]

Originally Posted by jdstefan22

The bulb is dependant on when your car was built. Pre 9/6/66, use 1895, post 9/6/66 use bulb 1445.

That sounds like the change occurred for the '67 model year?

A 1445 is a low power version of an 1895. Its about half the power (i.e. heat) and half the light output. The higher power of an 1895 may tend to melt the lens on the light holder or possibly Ford decided a dimmer light was more what they wanted.

I would imagine the exact time required for the light to go out varies quite a bit. Mine only stays on for around 10-15 seconds.

[jdstefan22]

I got my info from the CJ Pony Parts bulb chart in their catalog, so not sure for the reason behind the change, other than I know I have read that the lens melting was a common problem, so your explanation makes a whole lot of sense why they would have changed to a less hot bulb.

If the 1445 bulb fits where the 1895 is called for in this particular application, I would guess it would make sense to use the 1445, so you dont melt the lens, why even bother with the 1895, unless they changed the plug that the bulb goes into after 9/6/66, doubtful they did though.

Other than that, I am not sure, but in a 66, that is about the only warning light I have in the car that illuminates red, other than the high beam switch, so I find it a cheap thrill every time I see it go on!

[Ivy66GT]

Originally Posted by jdstefan22

...unless they changed the plug that the bulb goes into after 9/6/66, doubtful they did though.

No need to. The base for an 1895 or a 1445 is the same BA9, i.e. 9mm bayonet. At only 15 seconds a pop melting the lens seems unlikely but then maybe there are some that stay on a lot longer than mine.

I agree, a 1445 sounds like it would fit and work in any of them. A 1445 is 1.9 watts, an 1895 is 3.8 watts.

[ghjedi]

Thank you Ivy66GT and jdstefan22! I really appreciate your detailed insights. This is definitely not a critical safetey component of the car, but I was facinated by that light when I was a kid and I'd like to see it work correctly again. My '66 has been in the family since it rolled off the dealer floor.