I bought a 77 that has a key cylinder on the drivers side front fender. The lock key fits it, so I assume it's original. I don't have an owners manual yet, and I'd like to see if this works. Does anyone know anything about how it works, or how to set and disarm??

When the car is off and everything shut (the windows don't count) just turn the key and take it out. If you open the door, the alarm will go off. It sounds the horn on and off with a flasher type control. To stop it, just put the key back in and turn it back, the pull the key out.

Ken Styer

Don't be surprised if the alarm doesn't work after all this time. It's very common for these to no longer work properly.

I'm not sure about the 77, but my 75 has all the wiring and controls for this system in the tool storage compartment. I would bet it's the same on yours. It is very common for the voice coil mechanism in the alarm horn (which is located behind the LR wheel) to corrode up and not function. I was able to drill out the rivets and repair my horn. The door switches that are on the latch pillars activate the alarm as well as work the dash "door ajar" light. There should also be an anti-tamper switch mounted against the key switch (it's the same switch as the headlight warning switches). There is a plunger switch against the hood that is located on the firewall near the distributor that activates the alarm the same as the door switches. When activated the alarm also interrupts the ignition circuit through a relay. Trouble shooting this system should not be extremely difficult if you have the correct wiring diagram for your car.

I spent a few hours researching and investigating the alarm (on my 75), When I bought her, I had no idea of what the lock on the left front fender was, let alone a alarm system (on a 75). I did not have a key that fit it, so you are one step ahead of me. I ordered a new lock, with key and a wiring diagram (which is posted on my garage wall) that I use ALL THE TIME. Starting from the lock, I started tracing all the switches and wiring. In my case, the anti-tamper switch (that 'big fish') mentioned was broken. The headlight limit switch is the same as this switch (also around 30 bucks). I replaced this switch, and found the hood switch (located above the fan blower motor) was broken also, so I replaced it. The doors have two switches. One is located in the front, these are for the interior lights and the door adjar. The swithes mounted in the back of the door are for the alarm. I had to readjust both of these. So to recap, there are 2 door switches, 1 hood switch, alarm lock and a anti-tamper switch, plus your horn. My system works like a champ now, but it wasn't easy. If you need any more help, let me know. bill0830

I just 'unearthed' the remains of the factory alarm on my 69' Coupe. Apparently, one of the previous owners had sawed off the lock in the rear end and glassed over the hole prior to re-painting the car.
My question(s) are:
Can a new alarm lock be purchased from GM? If so, does anyone have a part number?
Does anyone know if GM made a door lock cylinder that also incorporates a switch that can be used for the alarm? This would be a more suitable solution for me since I really don't want to drill any holes back in the body for this switch.
Any suggestions or advice would be greatly appreciated!
Thanks-
Elm.

Starting around 77 or 78, somewhere in there, the lock cylinder for the alarm was removed from the body and incorporated in the left door lock. Locking or unlocking the door with the key from outside set or shut off the alarm. So the parts are available for conversion.

Ken Styer

Just a thought anyone every use the key switch for a cut off switch? Like instead of turning the alarm on it kills all power to the engine
Just wondering
Glenn

If the hood is closed the kill switch works well. If there is acess to under hood it's easily defeated, but only by someone who knows how. So it stops rookies and joy riders.
Another is a fuel cut off. Mount a valve under the floor, with a lever under the seat. The car will start and run a very short way, then run out of gas. Not many theives try to restart a car that let them down.
A starter interrupt also works. A hidden switch that prevents the car from being cranked when the key is in it. Also not to hard to overcome, but again You need to know what you are doing.

Ken Styer

Suttvette- are you sure you have a 77? In 1977, the alarm key mechanism was moved from the left front fender to the drivers' door lock mechanism.

I hate to cause extra work for you, but it seems your vette isn't a 77, maybe a VIN search, or the DMV can confirm this for you.