Kiwigreg

Hi
I can't find an existing forum on this topic, but that may be my search criteria.
I am trying to repair/reactivate the Anti Theft system on my 74 Corvette - an American, imported into Australia.
The key switch in the front right fender is working OK and I have a clicking from under the car when the switch is on (key vertical) and I lift the hood. So I guess that means that part of the circuit is working, even though the flasher unit (if thats what it is) is not working properly.
However the engine cut off (if there is one) is not working.
I have the Factory Assembly Handbook but can't work out from that how thongs are supposed to work.
So - is the clicking noise under the car a flasher unit and what is supposed to flash if the alarm is engaged.
What is the bulb/cover under the Left Rear Guard (which I think from the Handbook is part of the Anti Theft system), what is in it and how do I access it.
Does the Anti-theft system also immobilize the ignition.

Also, where the wires run from the Anti-theft switch into the wiring harness in the firewall there is a 6 inch grey-ish wire coming out of the same point that has a black rubber hooded plug on the end. It doesn't appear to go anywhere (there is nothing nearby that looks like it needs a plug/cover).
However, inside the hood it looks like some sort of connection has broken off - but not sure. Again I can't see anything in the Handbook.
Any ideas ?
Greg

Mike Ward

A Kiwi in Melbourne?

The alarm systems on '74s and similar are very crude- no flashing lights, no ignition immobilizer. They simply activate a single horn hidden up under the left rear fender. Thieves figured out very quickly to snip the wire prior to breaking into the car.

The flasher unit is located in the jack storage compartment, this might be what you're hearing. If the horn is gone or disconnected, the flasher unit will have no load and not function.

Peterbuilt

Does this help?

LancePearson

Mike! So that's what the flasher in the jack compartment is! Thanks...will probably change it now that I know what it is and renew it! It has to be an antique by now!

Kiwigreg

Hi Mike (and Pete)
Great information thanks. The Kiwi in Melbourne thing is a long story - I'll save that for another day. A few more questions for you (both) if thats OK:
1. What does the flasher unit under the jack then do ? Does it "pulse" the horn ?
2. Looking at Pete's 1st pic, is there some sort of link to the door switch that is a similar set up to the bonnet switch

3. Pushing friendship - and thoughts on my 3rd Q, as follows:
Also, where the wires run from the Anti-theft switch into the wiring harness in the firewall there is a 6 inch grey-ish wire coming out of the same point that has a black rubber hooded plug on the end. It doesn't appear to go anywhere (there is nothing nearby that looks like it needs a plug/cover).
However, inside the hood it looks like some sort of connection has broken off - but not sure. Again I can't see anything in the Handbook.
Any ideas ?

Thanks guys
Greg

corvetteload

yes, makes the horn beep, without it it would be constant blaring not the beep--beep-beep (I think)

Paul L

Yes, it does pulse (beep-beep-beep). As Mike has noted these devices are very crude now although they were pretty modern for 1974. There were aftermarket kits available but very few new cars in that year had them factory installed.

The activators are one under the hood and the courtesy light switches for the doors. The "door ajar" switches at the rear of the jambs are a separate system. Do note that the system does not have a timer: it will sound until the battery goes dead.

In 1978 or so, switches were added to the t-tops, making a total of five. The activation mechanism was moved from the front fender to the driver's side door lock.

noonie

That should be the micro switch that prevents tampering with the key switch.

Peterbuilt

You may be missing #1, it is the same part as the headlight switch that lets you know that the headlights are up.

Kiwigreg

Thanks Guys - a great help, though it makes me realise how little I know about all this stuff. Still learning !

Paul, you said:-
"The activators are one under the hood and the courtesy light switches for the doors"
Does that mean that activating the courtest light switches by opening the door when the anti-theft alarm is on would have activate the alarm/horn?

Pete - great diagramatics - where did you get those (are they available for purchase)?
Also is the micro switch that Noonie is talking about the same as the #1 switch you are talking about ?
I don't have any of the Parts 1, 2, 3, 4 near the anti-theft switch, so figure it has been removed or lost at some time. However the Eng Wiring Harness plug looks about the same.
Can I buy those parts via the likes of Corvete America ? I have looked for the headlight part before and struggled to find it. Do you know Pete.
Thanks for all your help guys - fantastic for those of us out here in the Colonies.
Greg

Peterbuilt

Hi Greg,
In post 3 the top picture was posted by another forum member.
The second picture is from the 74 Service Manual Page 12-47.
The picture in post 7 came from www.willcoxcorvette.com (sponsor- on the left),
they have the (micro) switch, one at each headlight and one more for the alarm. 2375k is the part #.
The drivers door switch (on the hinge side) has 3 wires
Ground for the courtesy lights, the "key left in switch" buzzer and the alarm wire.
The passingers side switch has 2 wires, courtesy light and alarm.
If you need those switches get them and the connectors from Willcox too as they are special.
Reguards,
Pete.

mrmagrath

Thanks for asking that question Greg! You've cleared that issue up for me. Good that you're a Kiwi in Melbourne rather than Brisbane right now. I have family in Dalby, but they're ok.
I'm restoring a 74 convertible in Christchurch. Great fun!
Cheers
Grant

Paul L

Paul, you said:-
"The activators are one under the hood and the courtesy light switches for the doors"
Does that mean that activating the courtest light switches by opening the door when the anti-theft alarm is on would have activate the alarm/horn?

Yes, opening the hood or doors activates the alarm.

BTGRN75

Ok I'm confused. How does the micro switch that prevents tampering with the key switch- have a relationship with the headlights on light?

mrmagrath

I think it uses the same type of switch as the headlight ones.
Cheers
Grant

Peterbuilt

The headlight system and alarm system are separate, they both just happen to use the same switch.

BTGRN75

Thanks guys

aussiejohn

kiwigreg,

G'day, where do you live? I'm in Highett and have a '74 AIM but have very little knowledge of Corvette electrics, however I know some people who do!

I'm a member of the Chevrolet Car Club of Victoria Inc. and our next meeting is in Moorabbin on January 31. You'd be made welcome and there are guys there who'll be able to help you.

Give me a ring on 9502 3227 if you want. I'm home most nights.

Regards from Down Under

aussiejohn