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Original C3 alarm system..

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Old 03-26-2002, 11:51 AM   #21
KenSny
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Default Re: Original C3 alarm system.. (BB wowbagger)

This is how I got the factory installed antitheft system working on my '75.

The first thing I did was to buy a wiring diagram of my car. I like the plastic coated (laminated) one from: Lectric Limited, Inc. http://www.lectriclimited.com. It's a nice working size and you can use a marker or crayon to trace wires. It comes in handy when you have loose wires and you don't know where they go, you can usually trace out the color and reconnect or find the other end of the wire very quickly.

1. There is flasher in the jack compartment that makes the alarm horn pulse. If it does not then that needs to be replaced. You can bypass this for a test. There is also a relay that you should hear click when you activate the alarm.

2. If the alarm goes off too easily, then I would look at the door and hood pin switches first. Get new ones and reset them - they are cheap ($2-3) from most local parts stores. If you have replaced the door weather-strip then the pin-plunger-stop is pushed in to far putting the triggering of the alarm on the "hairy edge".

The hood alarm pin switch is located in the engine compartment, on the passenger side, near the cowl edge.

The door alarm pin switches are on the lower rear door corner (at least in '75) and it includes the door ajar warning light on the gauge cluster dash (the interior lights pin switch are in the front near the hinges).

There are access panels in the front of the rear wheel wells. They are the 3" x 5" metal covers for the rear body mount bolts and are retained by 4 little hex screws. If you remove the covers, you'll see the wires within the door jamb, behind the switch. Might make working back there a bit easier. You usually have to take off the rear interior quarter trim panels too. It is a real PITA to work on the wiring behind these switches, but you can usually replace the switches without removing the access panels.

There is a wire running between the 2 switches along the front of the storage compartments under the carpet. Check that the wire is good and not shorted. Rig up a test light from one side to the other to check for a short. An open would not cause the alarm to trigger!

3. Check the alarm horn under the driver's side rear fender. Apply 12v to see if it works.

4. In the engine compartment on the driver's side fender, and it is a PITA to get at, is the keyed arming switch (lock cylinder). You will need to get at it from under the car by removing the carbon fuel evaporation canister first. You may even want to remove the windshield washer bottle (I did because the pump was not working anyway, so as long as I was there....). Like I said it's a PITA! Some people have small enough hands that they can get at the switch from the top, but not me.... and you have to be able to contort your arms to get a wrench in there, so I think it is less hassle to come at it from the bottom.

It is supposed to have a "anti-tampering" switch (looks like a headlight button switch, not the one on the dash but the one up by the light buckets). Sometimes this is broken and it can be removed. This switch is currently (2001) about $35 from Corvette Central and Zip. You can by pass this "feature" if you are short on cash. Personally, if you are going to all the trouble to fix the alarm, you might as well protect this area by buying the switch if you need it.

I spent the better part of two days, tracing every thing down and replacing the switches, etc. Now it works like the General made it. This system is NOT high-tech but it works! BTW: my problem was the tampering switch behind the key switch was broken (the alarm would never set and came on as soon as the key was turned) and the flasher was not working which let the horn blast continuously instead of pulsing.

On my car the flasher is a Delco #552 12V (looks like a normal turn signal flasher for that era, GM #491391) and the relay is a Delco #878 12V (GM #1115878 - discontinued). If you need to replace these and you are not NCRS picky, then try someplace like NAPA, AutoZone, JCWhitney, etc. Or possibly even an electronics supply house like Radio Shack, maybe even Summit or Jegs. I have seen these offered at swap meets, but how can you tell if the used part you are buying is going to work when you get it home? You sure can't return it if it doesn't work!
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Old 03-26-2002, 12:34 PM   #22
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Default Re: Original C3 alarm system.. (KenSny)

Thanks for a most informativ post..This will help me alot..Thanks again :cheers: :cheers:
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Old 03-26-2002, 12:51 PM   #23
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Default Re: Original C3 alarm system.. (BB wowbagger)


My '82 alarm works great! It's even got T-Top sensors so if someone messes with them from the outside the horn will go off. I am keeping the alarm factory, but I am adding a remote keyless entry module, just for the convenience factor. I was thinking about adding a remote start module too, but then I found out they are $250 and decided not to. It would be cool to say to your friends "Check this out "Beep Beep" ....Vrooooooom" from outside the car.
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Old 07-28-2010, 05:13 PM   #24
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On my 1969, the 1 inch round **** that you are talking about is the Wiper Override Switch. This **** turns left and right and is located between the Vacuum override pulldown valves below the Steering column. It is used to stop the WSW motor while it is running to change the WSW blades. Its use is documented on page 16-17 of the 1969 Corvette Owners manual.

These switchs can cost Over $50 on EBAY. If your car has a 1 piece(aftermarket) hood that eliminates the WSW door, you do not need this ****, you could probably sell on EBAY.
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Old 07-28-2010, 05:37 PM   #25
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I believe the '73 is the first year with the single piece hood...if so (and a genuine '73), that **** is not the WSW pause switch since you would not have one. It's the odometer reset ****. Push AND TURN the **** to reset the odometer - you have to move the odometer numbers by twisting. And yes, this would feel like a 'radio tuning ****', a little springy and gritty when turned.

My alarm works perfectly too, after replacing the relays in the jack compartment.

Last edited by spinadog; 07-28-2010 at 05:39 PM.
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Old 07-28-2010, 09:35 PM   #26
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Old 07-29-2010, 09:28 AM   #27
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I already have a Viper alarm on my '74 (came with it) and I like it for the remote door locks...can I rewire my factory alarm as an additional security device to maybe kill the circut to the ignition or something like that ?
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Old 07-29-2010, 09:56 PM   #28
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Good informative thread!
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Old 07-30-2010, 09:17 AM   #29
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Quote:
Originally Posted by bluthundr View Post
Coming off the control switch it says to coutersy lights and PC & Cigar lighter.
What is PC and what does the lighter have to do with it??:"
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Old 07-30-2010, 10:24 AM   #30
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This thread is from 2002 and that diagram is from the Twilight Zone.
Here is the one I use , I think its easier to follow.
Name:  Alarmdiagram72-73.jpg
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Old 07-30-2010, 10:34 AM   #31
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For those of you wanting to use a common standard horn relay from a 78 vette , here is a pic of it wired up. In the diagram I posted above, the connector on the relay is "open end view", NOT "wire end view."
I believe in some cars the pink wire can be orange ( never seen this myself but others have told me this).
Name:  alarmrelayusinghornrelay002.jpg
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Old 07-30-2010, 05:02 PM   #32
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What year is your C3
My 1979 Anti-Theft Alarm works just fine after replacing the Relay Switch.
What is your specific problem with your alarm
EWJammer - SD
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Old 07-30-2010, 06:13 PM   #33
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BB. I have a 1976 (Early). When I purchased it the alarm wasnt working. Turned out to be the horn itself. Changed the horn and all good. It is more of a deterrent than a fail safe antitheft system. But having said that I have scared the crap out of myself when I have opened up the car and forgotten the alarm is on.For the nanosecond or two you get WTF is going on!!! The only problem I have had since then is the actual key switch on the fender. It was a bit erratic so I replaced it with a new one from Ecklers.

Regards

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Old 11-28-2014, 01:14 PM   #34
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I have an odd one. 1976. The alarm will work properly on occasion. I tested all the leads and all are in good order. I replace the flasher and same issue. If I bypass the flasher the horn sounds steady when any of the switches are closed as is proper.

I just can determine why the flasher is sporadic. Could there be too much resistance in the system to allow it to function properly?
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Old 10-19-2015, 08:28 PM   #35
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Default 82 Collector Edition

Anyone have the diagram for the wiring for an 82 CE for the entire alarm system? I have the shop manual but was hoping for something better.

Also, does anyone have a picture or a diagram of the alarm switch that is supposed to be under the hood?

Thanks guys.

Last edited by asby69; 10-19-2015 at 08:30 PM.
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Old 10-20-2015, 09:00 AM   #36
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My 73 has it working properly. I had to clean the contacts in the key switch to get it working.
Fran
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Old 10-20-2015, 09:06 AM   #37
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Quote:
Originally Posted by z10kl View Post
Coming off the control switch it says to coutersy lights and PC & Cigar lighter.
What is PC and what does the lighter have to do with it??:"
That is the connection to positive +. It is shared with the the other items listed. I do not know what the PC is. Maybe "positive connection"?
Fran
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Old 10-20-2015, 12:04 PM   #38
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Quote:
Originally Posted by asby69 View Post
Anyone have the diagram for the wiring for an 82 CE for the entire alarm system? I have the shop manual but was hoping for something better.

Also, does anyone have a picture or a diagram of the alarm switch that is supposed to be under the hood?

Thanks guys.
asby, you do realize that this thread was started over 10 years ago, resurrected 5 years ago and then again last year. Many of the folks that posted back then are no longer reading C3 threads or are even here any longer. My only point, is that the best way to get a relevant response to such an old thread, is to actually start a new thread with your question in the subject line.

As you probably know the alarm system on the C3 evolved quite a lot over the years from the '68 through the 1982. From a very basic, but functional system early on, to the 80's when it had become quite sophisticated and even ended up with its own control module.

Here's a diagram of a 1980 that is closer to your 1982...

https://www.corvetteforum.com/forums...ck-wiring.html

Here's a diagram of a 1981 that even shows the Theft Deterrent Control Module...


https://www.corvetteforum.com/forums...rm-wiring.html

I was able to find these by doing a quick search on the internet. Ironically both linked back to the Corvette Forum.

Hope this helps and good luck... GUSTO
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Old 10-20-2015, 02:38 PM   #39
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This is the only thing that doesn't work on my 82 and wouldn't have a clue where to start??
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Old 10-20-2015, 09:27 PM   #40
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Gusto, thanks for pointing out the age of the thread. Next time I'll look before answering! Embarrassed emoji!

Fran
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