72 Seat Belt Warning Light

[Dan A.]

The seat belt warning light on my 72 LT1 coupe will sometimes come on and remain on for 20 seconds when using the turn signal or when activating the high beams. It works normally when the key is turned on but I have noticed that it will stay on for the 20 seconds even if the key is turned off before starting the car. I have years of maintenance records and noticed the the prior owner replaced the original seat belt light timer with some sort "upgraded" timer several years ago. All other electrical functions work perfectly. Any ideas for a cure?

[Don L.]

Re: 72 Seat Belt Warning Light

Dan, what's your car's build date?. Early model year 1972 had the timed warning light that lit for approx 15 seconds after it's energized then extinguishes on its own. Beginning somewhere around late December 1971 (I think to comply with January 1, 1972 FMVSS regulations), the occupant sensor system was put into production. The answers to your issue may depend on which system you have. Build date will help to sort through the issue.

[Dan A.]

Re: 72 Seat Belt Warning Light

Don,
it is an early car, built in August of '71. It was also a Canadian export car, if that makes any difference. Thanks for the reply.

[Don L.]

Re: 72 Seat Belt Warning Light

It's an early car with the timer set up then. Mine is too. In fact, mine is an August '71 built car, just like yours. When my timer failed a few years back, I couldn't find a replacement, so I had a solid state unit put inside the original unit's casing. It worked for a few months before failing. I think heat killed it.

I eventually found a NOS timer and installed it with no recurring problems.

Have you checked your ground connections?

[Dan A.]

Re: 72 Seat Belt Warning Light

I have not, and in fact i don't even know where it is located. Can you shed some light on that? I have looked in my AIM and found a relay, but no mention of a timer. Are they one and the same?

[Don L.]

Re: 72 Seat Belt Warning Light

Dan, the "timer" is GM part#3961500 and it can be found high on the inside firewall, behind the passenger side dash pad. Remove the pad and you'll find it to the right of the center gauge cluster. It's a hard part to replace, since it was only used from August 1971 till December 1971 (or so). I don't know how to test it, but I determined mine was dead when I pulled the canister off the base and found the thin wire broken. It's the wire that gives the timer it's function. When the wire heats up, it opens contact points and extinguishes the WARNING light on the dash. Make sense?

[Dan A.]

Re: 72 Seat Belt Warning Light

Don,
it makes a lot of sense. I figured out that the PO used a timer made by Wolsten Tech and must have figured out a way to make it work, sort of. I will try to find it in the location you described. Thanks again for the replies.