BaysideC4

I read through the archives and didn’t find anything that was similar to the problem I experienced yesterday.


I have a 1990 C4 (alarm unit hidden in the front boot somewhere, pretty much inaccessible). After washing my car I started it up and the alarm went off. The doors were never locked, no sensors were tripped. I could not shut the alarm off regardless of what I did. I noticed that the alarm stopped for just a moment when I the starter engaged when I turned the key. After starting and stopping the ignition a few times the alarm stopped, but a few minutes later it started again. This went on and off for at least 30-40 minutes.

Finally the alarm stopped for good. I am assuming that the alarm unit got wet when I was washing the car (it’s not the most watertight vehicle I ever owned) or the alarm system is starting to go.


Has anyone had anything like this happen? I would gladly disconnect the factory alarm and install a new one if I could get to it, but I don’t think that’s happening.

Any help or guidance would be appreciated - Thanks

Indycam

Hiya BaysideC4
Does the alarm work now ? Can you get the alarm to go off ? And by off I am asking if you can get the alarm to scream ? If you can get it to scream , does it turn itself off after a bit ?
You can unplug the horn under the car so that it can not scream and put a light bulb in its place so you can see when the thing goes on and off . Your ears and neighbors will be thankfull .

BaysideC4

I will test it today - is the alram siren located near the air horns?

One thing i forgot to mention, a few weeks ago i rolled up my window and a piece of rusty felt came out of the drivers side window. I plan to replace that part - but i guess thats one more place that water can enter from. Anyone ever replace that part?

Indycam

Hiya BaysideC4
#1 Yup .
#2 Yup .
#3 Can I try your bike someday ?

BaysideC4

You can definitely take the bike out for a spin if you’re in NYC (ride at your own risk)

So, I can’t get the alarm to sound and to tell you the truth I don’t know if it ever worked correctly because I have never tested it like this before. I do recall it going off once when I locked my doors while my trunk lid was popped opened, when I fully opened the lid the alarm went off.

I locked the door with the window opened, reached in to manually unlocked the door – no alarm, however the immobilizer was activated and the car wouldn’t start. I even tried the hood release trick as this set it off once in the past, but still nothing.

Do you think I shorted out the siren?

Indycam

" (ride at your own risk) "
You would lend your big old bike to a doofus to ride in NYC and not take full responsibility for any and all the stupid things I might do ? Deals off !

"Do you think I shorted out the siren?"
Could be .

"I locked the door with the window opened, reached in to manually unlocked the door"
This does not sound like it would set off the alarm . You should be able to sit in a locked car and unlock it from the inside without setting off the alarm . The car does not know if you are inside or outside . I could be very wrong on this.
The hood open test should set off the alarm , I've had it scream at me a few times for this .

BaysideC4

Does anyone know a sure fire way for me to set off the alarm?

BaysideC4

Anyone intimate with the factory alarm in 90 C4 (located in the front boot)? Its functionality, location, etc???

Thanks

KirkF

Its been about 2 years so this is from memory:

It is located in the front boot/trunk/whatever you wanna call it. Reach deep into the passenger side hinge and you will find a small box clipped way back in there. You can unclip it and and there is enough wire to pull it forward so you can see it.
If you remove it, the car won't start.

There is no siren with a factory alarm. It uses the horn only. If you have a siren, there is an aftermarket alarm installed as well.

I went searching for a problem with my factory alarm, and found 3 other aftermarket alarms buried in my car.

Kirk

BaysideC4

Thanks Kirk -

I havent actually seen a siren, but when it was going off it was clearly not the trumpet airhorns so I made my own assumption. In fact I honked my horn at the same time to verify. It sounded like a buzzer type of siren (also my foglights flashed).

Thanks for the clues to finding it.

KirkF

I would guess you almost definetly have the remnants of an aftermarket alarm in there. I would look under the dash by the steering wheel. Thats where I found two in my car. (The third one was in the trunk). I had to tear out bushels of old wiring to straighten out the mess.

(In my case the car doors spontaneously started locking themselves after I started the car, and if I opened a door it would set off the alarm. Very embarassing)

I forgot to mention to you that the alarm used on the 89,90 models is a different setup than all the other years. (Important if you are reading other posts about problems, wiring, etc) Also the alarms installed world wide were different depending on area. (ie: UK cars got some other other options) but i think the USA and canada cars all got the same setup.

Kirk

BaysideC4

The alarm finally dried out completely. It works now! When I pop the hood or open the door by manually unlocking it through the window, it goes off normally.

Now I need to find out where the waters coming from.

BaysideC4

Kirk,

I just wanted to send out one last update. There is a seperate horn for the alarm (it does not use the air horns). It may be a year specific thing but I thought this was a good piece of information just in case someone else has this problem down the road.

KirkF

Hmm. Learn something new every day!

Glad your issues worked themselves out. Digging through porsche wiring sucks.

Kirk

Indycam

Hiya BaysideC4
Is a siren and a horn the same thing ? I think not .
When KirkF pointed out that
"There is no siren with a factory alarm. It uses the horn only."
he was pointing out a clue . A clue that I missed completely .
When KirkF posted that , I understood what he was talking about .
If it had a siren , it probably was not the factory alarm going off cause the factory alarm uses a horn .