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OEM 79 Anti-Theft Alarm

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
I finally repaired the driver side door lock. When I lock the driver side door with the key I can hear the Anti-Theft relay engage. But when I remove one of the t-tops or open the hood to close one of the Anti-Theft switches nothing happens. How do I properly test the OEM Anti-Theft Alarm? Since I hear the relay and close a switch and nothing happens, what might be the potential issue here as to why the alarm is not working? ;help
 
B

bmotojoe

Guest
Could be as simple as a dirty pin switch or could be more complicated like a bad relay as there are several at least on the 1977, and also the horn unit itself.
Maybe the 1977 drawing will give you a little incite on what’s going on and a few places to check. You should have a DC meter or a test light to check circuits.
Hope this helps,
Brian
 

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
Hey Brian. The 5 switches and the relay are fine. I will troubleshoot anti-theft flasher and horn later tonight.
 

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
Well, I have a bad anti-theft horn. I am hoping all I have to do now is replace it and then "waa-laaa"....
 
B

bmotojoe

Guest
Yea same with my original trumpet style horn when I purchased my car back in 1982. The coil was shot so I replaced it with an aftermarket 12 volt compact design style OEM replacement. The first one I installed I didn’t like the sound, found out it was the high pitch horn so I returned it for the low pitch but it is all about personal preference. I used a metal bracket I had that was anodized that supported an in dash stereo, the type with holes punched about 1” apart. Before replacing your horn make sure it has a nice clean ground as it won’t work if it isn’t grounded well.
Brian
 

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
Brian, you just mentioned what I was wondering. Was the Anti-Theft Horn Low Pitch or High Pitch? Suppose I can get a horn at AutoZone or Pep Boys? Hey, by the way, I am on my third wheel with cleaning and repainting. So far so good! The rear window trim appears to be more difficult as the fine steel wool is not removing most of the paint easily. Thinking of using plastic razor blades.
 

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
Well, I replaced the horn with a low pitch universal horn that has two pig tails (connections). One for your constant 12v and the other is your signal wire. Just connect the two wires to the two terminals. Set the anti-theft circuit and then pop the t-top or hood to test. All works well!
 

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