1970s 75 Eldorado Theft Deterrent System

[Richf1966]

I am a new member to the club as well as this forum. I have a question regarding mid 70's theft deterrent systems. I recently purchased a 75 Eldorado convertible with almost every option available, the theft deterrent system is one of them. It appears a professional such as a dealer disconnected the system. I believe this for two reasons, the first is that the electronic controller is up inside the dash and only accessible by removing the dash pad. The connectors for the system are located up inside the dash above the radio. Another sign is that the indicator lamp socket was tucked away in the `dash conduit with a plastic "slug" inserted into the lamp socket. This slug is specifically designed to keep foreign objects from getting into the socket and shorting the wiring. Other than that, the system is completely in tacked.

My question is to those of you who have a mid 70's Cadillac with the theft deterrent system, is it worth it to reconnect the system and have it function as it was designed or leave it disconnected as its not worth the hassle assuming these systems were unreliable and more of a nuisance?

I appreciate any useful input and I have included pictures of the harness and the bulb socket with "slug".

[TJ Hopland]

I had a 73 that had it.  Discovered that it was even an option when I started hooking up various wires that were disconnected trying to get other things working.  I never really dug into it.  I think when I was messing with mine someone posted a link to the manual but it was a long time ago so I have no idea where it was.

[The Tassie Devil(le)]

Actually, the plastic plug is there to stop the lamp holder from slipping down the wire, thereby opening the lamp live end from grounding out on any metal piece nearby.

It physically acts as a lamp base, holding everything into position.

Bruce.

[bcroe]

I see the system detailed on page 15-8/9/10/11 of
the 1975 CADILLAC SHOP MANUAL, part no 109 9842.
There is a lot of wiring, such as an extra switch
to every door (as opposed to just the drivers),
hood, buzzer, relays, control switches, etc.  Most
important there is an ELECTRONIC CONTROL BOX which
may by now be of unobtainium.  My experience with
EFI for that model implies the box may be relatively
simple and repairable (if not impregnated), but first
you must find someone who has knowledge of its inner
workings. 

The top of the dash is not very difficult to remove,
better than other cars forcing you to crawl under
the dash.  Bruce Roe

[bcroe]

The system in the 76 manual appears very similar,
possibly identical.  Bruce Roe

[Steve Lomas]

I have the same car with the theft deterrent. Just curious if you still have the key to set the alarm- on the driver side front fender? Also the siren under the hood on the wheel well?

It's not something I ever used, where I live I don't usually lock my cars, but I wired the siren up to a switch under the dash- since it's fun to use when you get waves etc 

Other than that you'll find this is a great forum- I've found lots of invaluable advice here.

[Joe G 12138]

   I had that system on a '73 Eldorado I had. I disconnected it because of a parasitic draw that would run the battery down. The power source as I remember it, was an orange wire connected strait to the alternator, which wasn't shown in the shop manual or wiring diagram. I guess that's how they kept the secret security setup a 'secret"  Joe Gibeault

[Richf1966]

I have decided to keep it disconnected as I have not gotten any good feedback when inquiring on several other threads. Its more of a novelty at this point. Just wanted to get it working and verify its functionality. Its more hassle than its worth since the car is now used only occasionally and not driven to places where that would be a concern.

[TJ Hopland]

I had that system on a '73 Eldorado I had. I disconnected it because of a parasitic draw that would run the battery down. The power source as I remember it, was an orange wire connected strait to the alternator, which wasn't shown in the shop manual or wiring diagram. I guess that's how they kept the secret security setup a 'secret"  Joe Gibeault

I kinda remember the same thing. Mine wasn't hooked up and I didn't think it looked factory but I hooked it up to see what it did.  I think it was later I found out it was the factory alarm.  Same car also had the track master brakes.  Someone liked checking all the option boxes. 

[bcroe]

The first systems attempted to sound alarms.  Jacobs
will let a car be driven just onto the street and
then shut it down, not where you want to be blocking
traffic in a stolen car.  Others track the car by GPS
and report by radio.  Bruce Roe