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Topic: 1980 anti-theft alarm help!!!!!

in Forum: C3 Electrical

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1980 anti-theft alarm help!!!!! (1/20)
6/25/14 1:48pm

Redwoman
Former Member
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Bellingham, MA - USA

Vette(s):
1980 loaded red on red. 68,000 original miles. Second owner. Well documented with all original paperwork. NCRS Founders Award 9/27/14. NCRS Top Flight 10/12/14.

Joined: 6/23/2014
Posts: 175

Can somebody please send the troubleshoot list for a 1980 alarm. I read another post that mentioned it but I am a new member still trying to figure out how to use the forum. I have checked all 5 switches they are all good!! I have replaced the wiring harness in the drivers door for the alarm didn't help. With the tops on hood close Ttops on when I turn the door key clockwise and counter clockwise nothing happens. But if I open the hood and turn the key counter clockwise the horn alarm sounds and pulses so I know the horn works. If I turn the key clockwise with the hood open nothing happens. I have even tried manually holding all the switches in to make sure they were not out of adjustment. Has anybody else come across this problem. I have read a lot about alarm problems on forums but none that explain this problem. PLEASE HELP!!!! Thank you.

|UPDATED|6/25/2014 1:48:40 PM (AZT)|/UPDATED|

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Re: 1980 anti-theft alarm help!!!!! (2/20)
6/25/14 5:02pm

rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1171

here are the diagrams and some info

http://www.C3VR.com/member_pages/4201_4300/4221/page-40-Anti-theft-system.jpg

http://www.C3VR.com/member_pages/4201_4300/4221/page-41-Anti-theft-system.jpg

http://www.C3VR.com/member_pages/4201_4300/4221/page-42-Anti-theft-system.jpg

Re: 1980 anti-theft alarm help!!!!! (3/20)
6/25/14 5:26pm

rraider1
Limited Member
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1171

With everything installed and closed and you turn the key CCW the system would be armed. no alarm should sound. if you where to remove a ttop or open a door or the hood the alarm would sound.

what you described with the hood open and turning the key CCW the alarm should sound that is normal.

you could use that method for each position. remove one ttop close everything else up if you turn the key CCW the alarm should sound.

Re: 1980 anti-theft alarm help!!!!! (4/20)
6/25/14 6:50pm

Thanks, I will try that with all the other switches to see what happens in the am. Let you know the results. Right now if I closed everything up set the alarm then open a door or hood or top nothing happens.

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Re: 1980 anti-theft alarm help!!!!! (5/20)
7/9/14 5:42pm

I did that on every switch and I hear the relay click and the alarm horn sounds like it should. So basically that indicates all the switches are good. I even tried a different relay for the heck of it and it did same thing. So what am I missing?? With hood closed. Tops on, I turn the key to left and horn doesn't sound. Turn key right to lock door. The alarm should be set. If I open the hood or tops or reach in to open door the alarm doesn't go off. I tried turning the key right first locking door then left to set alarm and still nothing happens when I open anything. What am I missing???

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Re: 1980 anti-theft alarm help!!!!! (6/20)
7/10/14 8:10am

rraider1
Limited Member
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1171

Some thing does not sound right. I believe that you should turn the key to the left CCW to arm and lock your door, you turn right CW to unlock and disarm. at least that is how it is for 77. it sounds like the components of the system are working its an arming issue. I believe this is how the switch works. when you turn it CCW the contacts close and if you turn back to center it should stay closed. when you turn CW the contacts open and when you turn back to center it stays open. That switch could be your issue. turn your key CCW leave it their then open the hood or some other area see if the alarm sounds if ok then turn it to center and see if it still works. If someone has a owners manual it should describe how to arm system, this is from the 77

http://www.C3VR.com/member_pages/4201_4300/4221/alarm.jpg

Re: 1980 anti-theft alarm help!!!!! (7/20)
7/10/14 9:47am

Adams' Apple

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Duncanville, TX - USA

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

Joined: 11/8/2003
Posts: 20201

Redwoman said: I turn the key to left and horn doesn't sound. Turn key right to lock door. The alarm should be set. If I open the hood or tops or reach in to open door the alarm doesn't go off. I tried turning the key right first locking door then left to set alarm and still nothing happens when I open anything. What am I missing???

I think we are all now thoroughly confused! Wacko

Turning the key CCW should lock the door(s) AND arm the system...unless the '80 car is different form the other years.
If you have to turn your key Clockwise to lock the door, then you would be disarming the system every time you locked it...but it would also seem that the alarm would go off every time you unlocked, and opened the door. Wacko

In your first post, you say this...

Redwoman said:
1:...if I open the hood and turn the key counter clockwise the horn alarm sounds and pulses so I know the horn works.

2: If I turn the key clockwise with the hood open nothing happens.

The first statement confirms that the system is capable of working.
The second statement is confusing....when you turn the key clockwise, it should dis-arm the system, and turn the horn off. Are you saying that turning the key clockwise does NOT turn the horn off? You must turn the key all the way clockwise to turn the alarm off...which should also be Un-locking the door.

From what I see, the alarm IS functioning....the problem is in HOW to arm AND lock the door at the same time. Your door key cylinder is not upside down by any chance, is it? The key should go in the cylinder cut side down...

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Joel Adams
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Re: 1980 anti-theft alarm help!!!!! (8/20)
7/10/14 10:10am

rraider1
Limited Member
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1171

Thanks Joel I was hoping is was not just me

Re: 1980 anti-theft alarm help!!!!! (9/20)
7/10/14 5:20pm

Sorry guys! I wasn't typing what I was thinking. Thank you for the lock instructions I actually did get the owners Manual out last night and read it again. Even I was confused. Been screwing with the alarm all day. So let me explain the problem the right way. With the hood closed, tops on and doors closed turn the key CCW to lock and set alarm. When doing this I don't hear the relay click. I can open everything hood doors tops and the horn doesn't sound. Back to square one. If I open the hood with everything else closed. Has soon as I turn the key CCW I hear the relay next to shift click and the horn sounds. I did this with every switch close everything except ttop and when I turn the key CCW Hear the relay click then horn sounds. Etc. Etc. The key is inserted correctly with the flat part up. We had checked that to but The lock can only be installed one way . So we are on the same page I believe I tested everything and it is all operational. But the alarm won't set. I have even tried a new relay, and, all new switches. Even tied a new lock cylinder on off switch and harness. Same exact thing like explained above. In the fuse panel there is a 10 amp fuse for alarm and a 25 amp for courtesy lights and alarm. Is there a circuit I am missing. I believe it consist of 5 switches 1 relay 1 alarm horn 1 flasher to pulsate horn and door switch to set on /off. Stumped !!!

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Re: 1980 anti-theft alarm help!!!!! (10/20)
7/11/14 8:41am

CCasey
Former Member
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New Albany, OH - USA

Vette(s):
1980 Coupe / Snowcrest White / L48, 350 / Comp Cam / Edelbrock Heads / Cyclone Intake / Holley Carb / Holley Fuel Pump / Patriot Headers / Dual Exhaust / Magnaflow Mufflers / 1964 Coupe / Riverside Red / L76, 327, 365hp

Joined: 8/17/2010
Posts: 173

Not that this means anything, but I am the original owner of my 1980 and the alarm system never worked from the day I took delivery. I can't tell you how many times I took it back to the dealer. No luck. It was just one of the many things that were not correct on my car.

Quality was definitely NOT Job One for Corvette back in the late 70's / early 80's.

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Chuck

Re: 1980 anti-theft alarm help!!!!! (11/20)
7/11/14 9:37am

Yipee!!!! I tried setting the alarm a different way and it worked. I turned the key CCW just far enough to set alarm but not lock the door. I open the door and the horn sounds like it should. So it has something to do with locking the door. When I read the owners manual it says the only way to arm and disarm the alarm is with the key. That the power lock or the button lock doesn't have anything to do with setting the alarm. But I had read where other members had said differently. This is the best forum!!

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Re: 1980 anti-theft alarm help!!!!! (12/20)
7/11/14 9:51am

Adams' Apple

Right....the only way to ARM/disarm the alarm system is with the door key. Now...you could lock the door from the inside with the knob/button, and then turn the door key ccw, and then you'll have both locked doors AND working alarm. My guess is that the switch is not properly set on the lock cylinder, or there is some other goofy problem with the switch.
Gettin closer, tho! You know now that the system does work....just gotta figure out why it's so temperamental. LOL

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Re: 1980 anti-theft alarm help!!!!! (13/20)
7/11/14 7:41pm

dskopp
Limited Member
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Oak Creek, WI - USA

Vette(s):
1981 Great White Shark. Red Interior, 350/190 hp. PS, PB (SS), A/C CC, T-Tops. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vettes Car Club. 175,000 Original miles!! Now own a 1998 C-5!

Joined: 5/21/2008
Posts: 1965

My 1981 Door and alarm works when it wants too!! Just like my drivers window!! But the procedure to lock the doors is: Key in the lock outside of the car to arm the system!!

Dan da Man !! Hug

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Re: 1980 anti-theft alarm help!!!!! (14/20)
7/23/14 12:57pm

Do you know what position the switch should be on the back of the lock cylinder. Right now it is a six o'clock. When I repositioned it at 9 o'clock. The alarm set it self without the key. I shut the door don't set alarm or lock the doors manually or with the switch. If I open the doors, hood or tops the alarm goes off. When it is at 6 o'clock the alarm works properly has long as the key is still in the lock. So when turned CCW the alarm is setting. But it is just a hair difference between having the alarm set and removing the key. Just that hair difference is turning alarm off to be able to remove key. So close but yet so far. So it definitely an alignment issue. I have not been able to find what position the alarm wire should be on the back of the lock in any books. When I use the diagrams from the big name vendors they are not consistent. If I wasn't for the NCRS judging coming up I wouldn't care about the manual alarm working. The two eyes in the head alarm works just fine. LOL. The last time NCRS judged my car when it came to the operations section the only deduction was for the alarm. I am trying to obtain the NCRS Founders award. I have meet most of the criteria but the next operations check requires the alarm to operate properly.

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Re: 1980 anti-theft alarm help!!!!! (15/20)
7/24/14 8:53pm

druzac
Former Member
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Joined: 12/6/2012
Posts: 15

I did not think that the alarm system was hooked to the t-tops until 1982. I had an 81 back in the day and had two sets stolen by the thieves breaking the window to steal the tops (never opening the door to set off alarm).

Re: 1980 anti-theft alarm help!!!!! (16/20)
7/25/14 3:52am

See learn something new everyday! 1980 had alarm switches at the Ttops. If the plate where the ttop pin goes in is chrome on your car somebody could of changed them.

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Re: 1980 anti-theft alarm help!!!!! (17/20)
7/25/14 1:15pm

rraider1
Limited Member
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1171

Here are pictures for 77 not sure what differences their are hope it helps

Re: 1980 anti-theft alarm help!!!!! (18/20)
7/25/14 1:22pm

Thank you. Next time I take door panel off I will try to reposition the alarm switch to the 3 o'clock position like in your picture. Let yon know what happens.

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Re: 1980 anti-theft alarm help!!!!! (19/20)
7/25/14 5:39pm

rraider1
Limited Member
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1171

Remember keep it simple (KIS) if you have an OHM meter you can put it on the yellow and blue wire of the switch. you are looking for continuity on the switch when you turn it CCW and back to the center. then when you turn the key CW and back it should be open. I believe you have determined that the other components are working correctly.

The only thing this switch does is when it has continuity (closed) it has setup the ground circuit for the anti theft relay so that when any of the switches (both doors, hood and both t-top) will complete the ground circuit to energize it and the alarm sounds

Re: 1980 anti-theft alarm help!!!!! (20/20)
4/28/25 4:49pm

Flinky
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Vette(s):
Corvette 1981

Joined: 4/28/2025
Posts: 1

Hi,

Many years have passed since wince when this thread was created but I really hope you can still help me.

I have an 81 corvette with the anti theft system and replaced the door lock cilindinders and I am wondering what is the right position for the alarm switches on the colinders.
I guess you managed to solve the puzzle so…should I settle them at position 6 (wires pointing down) or 3 /9 (wires pointing forward) ?

what I noticed using a tester is the following:

Wires pointing down (6 o clock): when you insert the key (key is vertical) there is NO continuity. When you turn the key left to unlock (key is horizontal) THERE IS continuity.

Wires pointing forward: when you insert the key (key is vertical) THERE IS continuity. When you turn the key CW to unlock (key is horizontal) the is NO continuity.

( But when I turn the key vertical to take it off there is again continuity when it should not be until I turn it tothe other side to lock the door…?)

hope you can still help me!

fil

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