early 72 fasten seatbelt light

[Keith L.]

According to the Judging guidlines and tech manual the early 72s only had a light that went off after 15 seconds. So are there no wires under the seats? Where is the 15 sec timer? Does anyone have a wireing diagram? Looks like all i can find show the later version.

[Terry M.]

Re: early 72 fasten seatbelt light

According to the Judging guidlines and tech manual the early 72s only had a light that went off after 15 seconds. So are there no wires under the seats? Where is the 15 sec timer? Does anyone have a wireing diagram? Looks like all i can find show the later version.

All the commonly available resources show the later system, and there was a time when the JM called for that later system on all 1972s. We learned slowly. If anyone knows these 1972 systems it is Sal Carbone. You can reach him through the button above labeled COMMUNITY and the click the MEMBER LIST on the drop down. Send him a PM or an email.

[Edward J.]

Re: early 72 fasten seatbelt light

Keith there is a thermal relay(timer) located under the pass side dash panel up high on the bird cage, there is a bracket left side that secures the dash pad. it is secured to that bracket.

[Don L.]

Re: early 72 fasten seatbelt light

Just like Ed says, early '72 cars had a 15 second timer mounted to the birdcage behind the RH dash pad. You might be able to get to it by removing the windshield wiper switch/plate. The timer looks like an old fluorescent light starter. These things are becoming very hard to find. The good new is that they were on all early '72 GM cars. Mine went south a few years back. I couldn't find a replacement so I had a guy make a micro timer board and he installed it inside the case of the original timer. That lasted for a little more than a year before it failed. I think it needed a heat sink and when it got hot it failed. Luckily, I found a NOS part on eBay. Bought it and it works like a charm. I do see them on eBay, however, not very often.

There were no wires under the seats until the interlock engineering change went into production.

BTW, when I say "early '72" I mean SOP through Dec '71. My understanding is that federal mandates required the interlock design effective January 1, 1972.

[Tom L.]

Re: early 72 fasten seatbelt light

And.... used ones often don't work. I have bought two of them and they're sitting in a box waiting for someone to figure out how to fix them.

[Reba W.]

Re: early 72 fasten seatbelt light

Don is correct in when the change was mandated; however, we have found the interlock system on some mid-December cars. The seatbelt model changed from C14 to C15 with the interlock addition.

[Keith L.]

Re: early 72 fasten seatbelt light

I see the timer thing. When I crank the engine it comes on and goes out as soon as the engine starts. When I cut engine off it flashes once. I unplugged the timer and it does the same thing. I put a jumper on the plug and it still does the same. Any ideas

[Keith L.]

Re: early 72 fasten seatbelt light

Seems to me if the timer was bad the thing would either stay on all the time or not come on at all. What symptoms did you guts have.

[Tom L.]

Re: early 72 fasten seatbelt light

It's been a while since I was really into finding one of those timers but here's what I remember about the circuit. The timer is quite simple, there's a ground and two terminals that feed a normally closed switch that opens when a heater is energized once the ignition switch is turned on. When the heater heats up it acts on a Bi-metal that opens the switch and keeps it open. Once the ignition is off the heater is de-energized and the switch opens. If the heater fails the switch won't open and the light should still be on. I did take notes on the wire colors if you need them. Hope this helps. Good luck!!

[Keith L.]

Re: early 72 fasten seatbelt light

Well that's what I would have expected. When I was putting new bulbs in there was no bulb there. That would tell me someone took it out because it wouldn't go out on its on. I put one in and it stayed on when I turned the switch on. But now it just stays on while the switch is in the crank position then goes out when you let off. And it flashes when I turn the switch off. It would be nice if it worked but it would be a bummer if I put all this back together and it stays on all the time I driving.

[Tom L.]

Re: early 72 fasten seatbelt light

I left the bulb in and pulled the relay. The relay is easier to get to and replace if one ever becomes availible or repairable. Have fun!!

[Edward J.]

Re: early 72 fasten seatbelt light

Keith, Is it possible that you may have installed the wrong bulb? I don't have my wiring dia. at work, But sometimes there are one wire bulbs like the dash lamps and sometimes other ones may have 2 wire bulbs with two posts in the socket.The owners manuel will give the bulb numbers. a one wire bulb in a two wire socket will do funny things.