Topic: Seat Belt Interlock
in Forum: C3 Electrical
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Lifetime MemberIndianapolis, IN - USA
Joined: 9/3/2006
Posts: 2429
Vette(s): Silver 1974 Convertible - L82 4 speed
Low miles (was only 8,900 when I bought it in March 2006) - Now 54K miles. Original owner bought it as an investment for son's college expenses.
2008 Jetstream Blue Convertible
The seat belt interlock works on my 74 - sometimes too well. Often, after I've had a passenger, the seat still thinks someone is there. If I jiggle the seat, sometimes I can get the buzzer to go off, sometimes I actually have to fasten the passenger belt to get rid of the buzzer and start the car.
Also, on rare occasions, when riding with a passenger, the seat belt warning will start going off even with the person sitting there.
Any ideas? Is there an easy fix, or do I need to get some parts and replace? I'm thinking that even as inept as I am with tools, I shouldn't have too much trouble - I think I can take a seat out and put it back!
Hopefully, it's not too much more than that!
Hopefully, it's not too much more than that!I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Welcome to the wonderful world of '74 Corvettes! 
There are pressure sensitive switches in the seat bottoms. They "sense" when there is weight(35lbs) in the seat, and remind you to fasten the seatbelt. If you don't it won't let you start the car.
The switches are a bit wierd, in that the contacts are on one end, and are connected to two strips that span the seat bottom, side to side. When weight is put in the seat, the strips move down, and pull on the end of the switch with the contacts, pulling the contacts together, and completing the circuit. The switches can get bent, or rusty, keeping them from functioning properly. The contacts on the end can get bent, too, and make it to where they want to stay connected all the time.
I have redone the switches in my '74, and it was a major PITA to get them cleaned, straightened, and working right again. Even so, every now and then, the light and the buzzer will go off. I have gotten in the habit of just raising the e-brake handle up one notch when that happens. That shuts off the buzzer, so it doesn't drive me nuts.
I don't know if these switches are available anywhere or not, but seeing that they are one year only, I'm thinking NOT!
I think I have a couple of extra switches here somewhere. I'll look and see, and take some pics, so ya'll can see what they are, and how they work...
There are pressure sensitive switches in the seat bottoms. They "sense" when there is weight(35lbs) in the seat, and remind you to fasten the seatbelt. If you don't it won't let you start the car.
The switches are a bit wierd, in that the contacts are on one end, and are connected to two strips that span the seat bottom, side to side. When weight is put in the seat, the strips move down, and pull on the end of the switch with the contacts, pulling the contacts together, and completing the circuit. The switches can get bent, or rusty, keeping them from functioning properly. The contacts on the end can get bent, too, and make it to where they want to stay connected all the time.
I have redone the switches in my '74, and it was a major PITA to get them cleaned, straightened, and working right again. Even so, every now and then, the light and the buzzer will go off. I have gotten in the habit of just raising the e-brake handle up one notch when that happens. That shuts off the buzzer, so it doesn't drive me nuts.
I don't know if these switches are available anywhere or not, but seeing that they are one year only, I'm thinking NOT!
I think I have a couple of extra switches here somewhere. I'll look and see, and take some pics, so ya'll can see what they are, and how they work...
Joel Adams
C3VR Lifetime Member #56 
My Link 
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
in Forum: C3 Electrical
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