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1970 Alarm problems

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Old Sep 28, 2009 | 11:54 AM
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Default 1970 Alarm problems

Hello. When I bought my Corvette nearly everything worked, except the alarm. I quickly discovered that the only rust on the car, was in the buckets containing the alarm relay and the flasher. They were rusted apart. Thankfully that's the only damage. I replaced the flasher already and found it difficult to replace the relay. It was discontinued in 1991 through GM and has to be ordered for around $40. I found on this site that a replacement may be a 1978 Corvette horn relay, for $6. I bought one this morning, installed it and turned on the alarm. With the passenger door open the horn didn't activate, and within a minute the relay was smoking. I double checked the wiring, it's correct. Any ideas? Should I buy the $40 relay? Now I'm afraid of cooking an ordered $40 part. Any help is appreciated in advance. Thanks! Jason
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Old Sep 28, 2009 | 12:44 PM
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Make sure the horn is not grounded , the relay and flasher does this to cycle it. Here is a wiring diagram. I posted a pic of a relay with wires attached I'll go look that up and make sure I didnt get the wires wrong.

edit-- Ok went and checked and the wiring colors for the relay in the pic are correct.
1970 stingray are your wires at the relay wired like the picture. I'm pretty sure the original wiring diagrams view of the 3 wire connector is opposite the wires end.


Last edited by ...Roger...; Sep 28, 2009 at 01:45 PM.
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Old Sep 28, 2009 | 01:56 PM
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The wires are attached as you show in the picture. I even tried switching them around. It seems as if I have a dead short somewhere. I have no idea where to begin, except the door switches. The driver's door switch is faulty and only activates the courtesy lights very sparingly. But I would have thought that the switch would close the circuit and activate the alarm intermittently as it's supposed to, not ground the system. A little while back I put another horn relay on and the horn chirped and then never sounded again. That relay became hot. Is it possible that I burned up the horn? And that's causing the short? This is frustrating....
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Old Sep 28, 2009 | 02:18 PM
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Originally Posted by 1970Stingray
The wires are attached as you show in the picture. I even tried switching them around. It seems as if I have a dead short somewhere. I have no idea where to begin, except the door switches. The driver's door switch is faulty and only activates the courtesy lights very sparingly. But I would have thought that the switch would close the circuit and activate the alarm intermittently as it's supposed to, not ground the system. A little while back I put another horn relay on and the horn chirped and then never sounded again. That relay became hot. Is it possible that I burned up the horn? And that's causing the short? This is frustrating....
Yes it is possible its the horn but I would have thought the flasher would have been clicking like crazy.
Try this unplug the flasher and turn the key in the deck to on,now take a piece of wire and ground the yellow wire from the flasher connector and see if the horn blows.
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Old Sep 28, 2009 | 02:21 PM
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One other test is to put a 12 volt test light in place of the horn and turn the system on and see if the test light blinks on and off like the horn would.
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Old Sep 28, 2009 | 02:58 PM
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Just run 12vdc directly to the horn to see if the darn thing works at all. I think the horn may be your problem, also.
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Old Sep 28, 2009 | 11:32 PM
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Thanks guys. I'll try that tomorrow if I can. I'll report any findings or progress.
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