Topic: ANTI THEFT HORN
in Forum: C3 Electrical
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Joined: 12/3/2007
Posts: 292
Vette(s): 1978 Corvette Light Blue
Pulled from the swamps of Miami!
Its a driver and back on the road!
Ok finally some warmer weather in PA. I jumped the dome light courtesy light timer and got the dome lights to work with the doors opened. It needs a new dimer timer $$$$, Thanks for all the help in that department.
But now the second problem I am working on.
I got the alarm horn to go off but its ging off when its not to be.
I cleaneed out the relay had some gook in there and now the relay is working fine or at least I think.
When I arm the alarm on the door key it sets the alarm off. The doors are closed the hood is closed I have the early version 78 so no roof alarm switches. Am I safe to say its something not grounded somewhere properly or a bad switch??? Pulled the wires from the 3 switches and tried to clean the contacts but still alarm sounds when armed. How do I check the proprer grounds? or is it something else? any info will be great???
I have one checklist from one forum that I am trying now but will let you konw what happens?
BB78 Thanks
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Duncanville, TX - USA
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
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#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
It could be that the relay is stuck. Either that, or one of the pin switches for the doors or hood is grounded. The terminals on the pin switches are TINY, and they get damaged very easily, so one of them may be grounding to the switch body. also, make sure ALL of the pin switches are adjusted to where the door(or hood) will actually open the contact when the door/hood is closed.
My first guess is the relay itself....
My first guess is the relay itself....
Joel Adams
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I took the relay apart because prior to this the horn would not go off at all, I could not get it to arm or work. Cleaned the relay because it was clicking... Now no clicking but it goes off as soon as I turn the key to arm it. With it armed and going off thee 3 switches are compressed I took each one apart and cleaned and sanded the terminals, but who knows??? Each as a black/ground wire but who can follow it where its to be grounded??? I purchased the electrical trouble shooting book and lookng at this also. Thanks for the info BB78
On my 79, the bracket for the hood switch kept bending down too far, causing the alarm to go off, Hope that helps.

Barry


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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Each of the wires goes back to the relay. When the switches are closed as when they would be with the doors/hood opened), they go to ground, which trips the relay on, which then closes the contact in the flasher, making the horn "beep".
I still believe the relay has stuck closed, keeping the system armed. Be VERY careful until you find/correct the problem. If the relay is stuck closed, it can overheat, and may possibly start a fire, unless the battery runs down first.
You can open the relay back up, and plug it in with the cover off, and see if the contacts are staying closed. If they are, unplug the relay, and see if the contacts open. If they do, then you definitely have a grounded switch pin wire(s) somewhere. If the contacts do NOT open when you unplug it, the relay is stuck. Be sure that the hood, and the doors are both closed while you do this.
If the relay appears to not be stuck, then remove each black wire from the pin switches one at a time, to see if the alarm goes silent. If it stays on with all three switches dis-connected, then you'll have to dig in to see which one is grounded somewhere except where it should be, which is at the switch itself. The easiest way to check that is by removing each circuit wire AT the relay itself. Whichever wire AT the relay turns the horn off is the circuit(wire) that is grounded. From there, you'll either need to trace the wire out to the pin switch, or simply run a new wire from the pin switch to the relay. I'll look at the wiring diagrams, but I'm not sure if the ones I have have the alarm system in them...
It sounds a lot harder than it really is...I hope this makes sense.
I still believe the relay has stuck closed, keeping the system armed. Be VERY careful until you find/correct the problem. If the relay is stuck closed, it can overheat, and may possibly start a fire, unless the battery runs down first.
You can open the relay back up, and plug it in with the cover off, and see if the contacts are staying closed. If they are, unplug the relay, and see if the contacts open. If they do, then you definitely have a grounded switch pin wire(s) somewhere. If the contacts do NOT open when you unplug it, the relay is stuck. Be sure that the hood, and the doors are both closed while you do this.
If the relay appears to not be stuck, then remove each black wire from the pin switches one at a time, to see if the alarm goes silent. If it stays on with all three switches dis-connected, then you'll have to dig in to see which one is grounded somewhere except where it should be, which is at the switch itself. The easiest way to check that is by removing each circuit wire AT the relay itself. Whichever wire AT the relay turns the horn off is the circuit(wire) that is grounded. From there, you'll either need to trace the wire out to the pin switch, or simply run a new wire from the pin switch to the relay. I'll look at the wiring diagrams, but I'm not sure if the ones I have have the alarm system in them...
It sounds a lot harder than it really is...I hope this makes sense.
Joel Adams
C3VR Lifetime Member #56
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Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
I also have push pin alarm sensors on the T Tops where the peg goes into the body when you push the lever up. Do you have these on your 78? Just another possibility...if the pin isn't going in far enough, the alarm may trigger near automatically...
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Thanks again for al the info will check it all out just as soon as I can get some time.Will let you know . again thanks for the info! BB78
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From what I can tell I have an EARLY 1978 corvette without the t-top alarm pins, either that or they forgot them. But from the wiring diagrams this appears to be an early model so no pins! As soon as it warms up again Will get the meter out and pull the relay and test it and the wires and also checked both ground straps under the car and cleaned and replaced so have not been able to recheck the alarm since. Thanks again for the info, I will get her working one way or another. Finally got the washer bottle back into the compartment. Someone had epoxy ed the door/cover that you go up in through...Like I said I would have loved to have had this car new! How could yo do such a thing????

"BUBBA" is everywhere! Who knows why people do such stupid things to their cars!

Barry

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in Forum: C3 Electrical
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