USI Mechanical Siren Alarm SA-3SCP

Hello. I recently picked up a vintage sealed Universal Security Instruments alarm system. Its a pretty old system from the 80's, the kind with a lock that mounts on the fender to arm and disarm. My dad had on on his 1976 Impala, and I used to have one on my 1965 Ford Falcon. Unfortunately, those cars are long gone, so I have no wiring reference. So here's the issue. The manual appears to be missing a section (the most important section of course.) I'm hoping someone on here has experience with these old alarms

The siren is one of the auto-sensing types, and says that it detects changes in the electrical system to trigger the alarm, such as voltage drop when the dome light or trunk/hood light turn on (Bulbs must be working.) It has a white and red wire. The siren bracket is ground. The red wire is shown going to one side of the keyed switch, and then to the fuse panel from there. The system comes with door pins and hood/trunk pins, but says they are optional as long as a courtesy light is in place (which there is.) The white wire is shown going to the door/hood/trunk pins if they are used, all wired together. The missing section (Section 8) describes how to wire it up I imagine. My question is: If I don't use the pins, what does the white wire connect to. Does it stay disconnected? At first, I thought it might connect to the courtesy light circuits directly, but I'm not sure if that's right, as that would tie all those circuits together. It's much different than the modern alarms where you hook up to the trigger wires. This is going to be going into my 87 Caprice, and I don't want to fry anything.

I'm attaching pics of the manual and the siren itself. If anyone can shed some light, I'd greatly appreciate it. Thank you.

I would think if no added pin switches are used, then the white wire gets capped off and is not connected to anything. The reason for adding a pin switch to an opening is if that opening does not have a light that comes on when the opening is opened.

Here's one on Ebay that maybe the seller would be nice enough to send you info on the paperwork it looks like they have with their system: Ebay Link

I remember putting those style alarm sirens in years ago (mid to late 70's ?) and every once in a while you needed to activate the siren so the bearing stayed free. If the sirens sat for lengths of time unused the sirens bearings would freeze/rust up. Also too, add a fuse in case of a short or overload of the sirens wiring. The ones I used to put in were the old Monroe Timer ones that pop up for sale now and again. I just wonder on those older ones if they were allowed to sound for so long then shut off or did they just keep blaring until the battery went dead ?

While things change I did buy this for a 70's GM car I have and wanted something from GM at the time:

GM Auto Alarm (Old School)

Jim

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1968 Chevy II Nova Garage Find 2012
1973 Nova Custom
1974 Spirit of America Nova
1973 Nova Pro-Street

Thank you for the reply.   I believe that as-is, this Universal alarm will keep going off until the battery is dead.   Universal sold a solid state timer module that could be wired in that shut the alarm off after two minutes. (I have one, but the wiring diagrams don't match my alarm, so I haven't decided if I will hook up the timer.)

One quick final question, the red wire going from the switch to the fuse box...   I've never connected a component to a fuse box directly before.   For the sensing to work, should it go to a particular fuse? The instructions call for a 20amp fuse.   I was thinking of jumpering it to the 20amp fuse for the courtesy lights/cigarette lighter.   Would that be the way to go, or is there a cleaner, more recommended route? Also, if I do go this route, do I need a second in-line fuse? If I'm going to do this, I want to make sure I'm doing it correctly so I don't walk outside one morning to a pile of burning wreckage.

Thank you!

I don't think it would matter what fuse as long as you do not overload that circuit and have the proper fusing in place. You will just have to research and see what different spots can take on your car. I know on my 60's and 70's GM cars there are circuits with fuses in the fuse block that let's say have a 20A fuse but what is in place on that circuit might only be drawing 5A and this then leaves me with technically being able to add 15A to it BUT you just have to look at things. No one likes melting the insulation off of the wiring.

Like I said, it's been years since I installed these type of systems and I cannot remember but there was something too about if the car had an electric fan that came on after a while after the car was turned off and the alarm was set, there was something special that needed to be done in either some wiring and/or a module ?. The memory is foggy on that.

If I had what you had,I might install it just as a conversation piece and then have a newer technology system in place with things like shock sensors, starter interupt, parking light flashers, auto reset, event memory, and so on. Just like myself, I bought that old NOS 70's GM alarm and I'll install it and probably not really use it but have a newer alarm on the car for more peace of mind. On my 68 car I have an old air shock setup on it with an underhood compressor that runs off of engine vacuum and I get all kinds of questions asked about it. The good parts is it is functional and working as designed.

Jim

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1968 Chevy II Nova Garage Find 2012
1973 Nova Custom
1974 Spirit of America Nova
1973 Nova Pro-Street