With key in the ignition and I open the door buzzer goes off close the door the buzzer silences. When I start the car the buzzer stays on and I can’t figure out how to silence it. Any thoughts would be much appreciated. Thanks

 

On a 77, headlight warning and seat belts is the same buzzer.
seatbelt will buzz no mater what for about 30 seconds. Headlight warning, well shouldn't buzz with engine running.
Do you have a schematic? Do you own the 77 electrical trouble shooting manual?

 

These buzzers are approaching 50 years old. Most people removing them permanently. Just a suggestion if you do not want to fiddle with it.

I disconnected mine from my 1978

 

And when mine didn't work properly, I fixed it. I hate locking my keys in the car.

 

77 & 78 Buzzer units are the same part number, the wire colors & Circuit numbers I used are for a Late build 1977...
To remove the cover of the buzzer unit you will need to carefully drill or grind the 4 plastic rivet heads joining the 2 half's...
To the best of my knowledge there are only 2 timed circuits to the buzzer, Seatbelt warning light & Seatbelt warning buzzer 2 separate circuits #237 & #238...
With the Seatbelt unbuckled Circuit #238 should read 0ohms to ground, Circuit #238 is the primary negative (-12vdc) path to the Seatbelt warning light...
Circuit #237 is the primary positive (+12vdc) path to the Seatbelt warning light...
You say the buzzer keeps sounding but does your Seatbelt warning light turn off in lets say less than 10 seconds?
If so, lets focus on Circuits #39, #237 & #150...
Circuit #150 is chassis ground...
There is a set of contacts inside of the buzzer unit. These contacts are N/C (normally closed) and act like a set of overloads or heaters in motor starter...
When the ignition switch is turned to either the On or Start position(s) Circuits #39, #237 & #150 are connected, or they should be, you would think this is a dead short
The small windings wrapped around Circuit #237 is a resistance wire, the end of the resistance wire is soldered to Circuit #150...
The resistance between Circuits #237 & #150 generates heat, the N/C set of contacts open. Buzzer & Seatbelt warning both should now be off...
Problem areas I have see on the inside of the buzzer is 1. The set of contacts have welded them self's together and 2. the small resistance wire end has broken off the connection with Circuit #150...
Because this is a resistance wire I have had good luck using a Silver Solder with a low temp melting point... I haven't had much luck using Normal solder...
When you see a number like C122 or C123 C=Connector as per the electrical drawing

 

I want to thank you all for responding. Exactly where is the buzzer? I do have a 77 passenger car manual which covers all models so I’ll check that. I’ve had this car for a year now and never had this problem. I’ll take all your advice and see if I make any progress. Thanks again

 

The location of the Buzzer may be in the Service Manual, I didn't look that hard for it...
Another good manual to have is the 1977 Corvette Electrical Troubleshooting Manual, you can find them on e-bay...Don't get a reprint or reproduction manual look for one like this Ebay Link:https://www.ebay.com/itm/15723032588...3ABFBMzub7jNxm
There is a supplemental 4 terminal connector added to the fuse panel. It should be White in color.
Make Note Of The Release Tab center right on the 4 terminal connector, that is the locking tab holding the buzzer in...
2 Connectors need to be unplugged before removing buzzer
The 2 wire connector C122 and a single Green connector with Grey wire that is plugged into the fuse panel.
Press the locking tab out on the 4 terminal connector and pull the Buzzer unit...
Here is a photo from the 77 Troubleshooting Manual, I added color to the LPS connector and wire...

 

You’ve given me a lot to consider and I’ll check this out when get a chance. Thanks

 

Both years, actually all years, it plugs into the fuse panel. The buzzer sound differs from year to year.

BM...didn't you make up a DIY unit? I recall the topic has come up over the years...no one is making a replacement board that I know of.

The orange wire leads to the buzzer box

 

Thanks, I did find the buzzer. Now I just have to find the time to work on this.

 

When you unlock the tab and start to pull the buzzer from the connector and you see the white 4 terminal pulling away from the main fuse panel don't be alarmed, the white connector slides on molded rails so there is a like a dovetail connection between the two...
Let us know what you find...