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72 seat belt warning switch


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While I didn't find any pictures, I found a good description of the system at the Chevelles Forum. I hope it helps.

First off, this system will only detect whether or not the seat belts have been pulled out of the retractors, not if they are actually latched to the buckles!

The driver's side and passenger side seat belt retractors both have a switch inside of them that ground when the seat belt is retracted (not pulled out). It's this ground that completes that utlimately provides ground side of the circuit.

The driver's side retractor should have a yellow/black wire coming out of it, This leads into the fisher body wiring under the carpet.

The passenger side has a white/black wire coming out of it, this leads up into the seat bottom. If a passenger or something heavy is sitting on the seat, a thin metallic strip presses against another one and causes this ground signal to travel back to the same connection as the driver's yellow/black wire.

This is where it gets tricky, there may be (2) wiring schemes. The one I have shows that the ground signal travels back to the neutral safety switch via a yellow/black wire. All seat belt warning vehicles have an extra set of contacts on the neutral safety switch. When you put the car in "D", this ground is then continued on up to the warning buzzer. The power side to the warning buzzer is tapped off the pink wires that feed the dummy lights or gauges for +12 volts. The warning light is connected off the black wire feeding the buzzer for ground and the pink goes back to another pink wire splice for 12 volts.

So, if you put the car in "D" and the driver's side retractor is still retracted, it's grounded reel sends a ground connection thru the fisher body wiring up to the neutral safety switch, then out thru the extra connectors to both the light and buzzer. BUZZZZZZZZZ. Pull out the seat belt, this "kills" the ground connection and the light/buzzer go off. NOW, if you have bucked up, but your passenger isn't, the system will not turn off because the passenger's retractor is still retracted and this ground is transferred thru the seat sensor (thin switch under the seat cushion) because of the weight of the passenger. Ground continues as described above back to the warning lamp and buzzer. They pull out there retractor, no ground again, system goes off.

Now I've seen some posts mention that the neutral safety switch's extra connectors have pink or pink/black wires meaning GM may have switched the +12 volt side of the circuit thru the safety switch, thus allowing +12 volts to travel to the buzzer and light when the car is in "D", rather then having it interrupt the ground path of the retractors. Regardless, operation is the same.

You should see a small box under the dash (most likely by the turnsignal blinker can)--this is the buzzer module.

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Thanks Dan, Do you happen to have a pic of where it is placed in the seat? I might be taking you up on that switch, mine is very rusted on one side. i am going to try and get the rust off, if not i will give you a shout.

Thanks Willie

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I was not able to come up with a seat that had a switch still mounted to it, but I did find a picture on ebay that should help. I will post the link to it. The plastic fastener on the wire attached to the switch mounts to the seat frame. It pushes into a hole in the frame. If you need more info just ask.

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Hey Dan, that would be great if you can post it. I stupidly took it off without taking a pic and now i dont remember on what spring it went.lol  I am surely not getting any younger.

Thanks

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I found one picture of my seats before I sent them off to Legendary. Keep in mind, these were previously re-done, so hopefully the switch is where it belongs.

IMG_2628.JPG

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I may be picking up my interior parts this week from Legendary,  if you need more pics let me know.

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