Bryan Welch

Does anyone know how to disable the alarm system in a 1991 Porsche 944S2? I installed a new stereo and didn't realize that alarm system monitors the radio. The car alarm now goes off randomly when locked. Note it's random, not a bit after the car is locked as one might expect. I park the car at home, lock it, and a couple hours later it might go off. Or it might go off immediately.

I pulled the fuse for "Central locking system / alarm system" but that didn't do anything other than make the red lights on the door locks stop flashing.

For installing this stereo, there weren't any standard stereo plugs for connecting the stereo to the car, so I had to make one. The original stereo was a Blaupunkt Lexingtion with a Blaupunkt EQ. I removed both the stereo and EQ and replaced it with a new stereo.

If anyone has any ideas, please let me know. It's terribly annoying to have the car alarm going off randomly, but I really don't want to leave the car unlocked.

Tye

I had a different problem with my alarm, but this may still be useful. I tried several things that didn't work. I finally disconnected the battery for a few minutes. I've not had a problem since I hooked it back up. Hope this helps.

Adrian

Dear Bryan,
Common problem across the whole Porsche range. Porsche installed on the radio rack a switch which activates the alarm if the radio was removed. Do you know what system was originally installed because with the CD-Players this switch was actually mounted inside the radio assembly itself but the circuit remains the same.
After your install what did you do with the green wire. The alarm wire is the green wire, you should find this wire sitting all alone. This wire has to be INSULATED not grounded. What is happening is that wire is floating around in the back of your dash shorting out somewhere setting off the alarm.
Every time it shorts out it is telling the alarm that the radio is removed.
My commnets are based on standard wiring and set ups of course. The green wire from the alarm is there somewhere.
Now theother cause of this problem is the glove box switch. Some people deal with the green wire problem in accordance with the Porsche TSB but when working around the glove box area damage the glove box switch. Makes sure that this switch is properly adjusted. There is also a TSB (Technical Service Bulletin) on this as well.
However, based on your post I think you will find your problem is a shorting out alarm wire,
Ciao,
Adrian
911C4
944

Adrian

Dear Bryan,
Something I forgot. The alarm unit itself has a fuse mounted on the unit. The central locking/alarm fuse actually only disables the central locking unit. The alarm is activated when the doors are locked by a microswitch on the bootom of each door actuator. You cannot always rely on the fuse description to tell the truth.
Check out the stuff hanging off the "Radio Booster" circuit.
Ciao,
Adrian

Bryan Welch

Where's the alarm unit generally located? I wonder if I could pull the fuse on the alarm unit to disable the whole system.

Adrian

Dear Bryan,
Now that is an interesting question. You live in the USA and drive a US version so I do not exactly know where your alarm unit is. I am sure it will be hard to get to for obvious reasons. All I can hope is that it is not like my 911.
Wish I could help more but maybe you need themanual for this. I will check my manual at home which covers the ROW version of your 944 and see where they have stuck it. I am sure somebody closer to home could answer this for you,
Ciao,
Adrian.

Bryan Welch

After all my worry about the installation of a different radio causing the alarm system to starting going off, it turned out that the radio alarm wire wasn't a problem at all.

The real problem was with the hatchback struts. A wire on the right side had been flexed too many times in 140,000 miles and was sending triggering the alarm. After replacing two inches of wire and a spade clip, everything's fine.

Of course, now the sun roof is broken. I'll work on that in the next few weeks some time...

Longtime76

Not sure if this is related. The alarm in my 87 944S doesn't work, and I have an aftermarket car stereo, which I dont remember. It does seem that the alarm may have stop working sometime after I put in the stereo. When I asked the dealer what any possible causes could be he suggested perhaps the battery has eaten through its mount and affected the alarm system which he said was below. However, there is no corrosion from the battery. Any ideas?