morris374

For some reason my alarm keeps going off when i start my car... for some reason my driver side door unlocks all the locks, opens the door but when i put the key in the ignition to turn on the car the alarm goes off! How do i disconnect / fix the alarm on 1991 420 SEL temporarily till i can replace it next weekend???

woodboat

Have you tried unlocking the car at the trunk? That disables the alarm on my 300sdl

Richard / E320

I had a similar problem with mine, so the easiest thing to do was disconnect the alarm module. It's the big black box on the far left in the photo.

I originally bought a used one off eBay, but it was a rip-off, not working any better than the one I needed to replace. No doubt someone had the same problem and peddled it to me, telling me it worked but listed it 'as-is'. If you don't want to buy a new one (expensive) and can't get one from a known working vehicle, save you money and just disconnect it.

morris374

where is this located ??? under the driver side floor?

Richard / E320

Passenger side. Easy access, under mat/carpet. Black box on far left. I cut the zip-tie to get better access to disconnect. Solves the problem of having the alarm going off unexpectedly, but of course you have no alarm to discourge theft.

If you can replace the alarm module with a known working one, it's worth the effort and easy to do. The problem with eBay and Craig's List is people will sell you one just like what's in your car already.

Also, for others with a similar problem, but the alarm going off when you unlock and open a door, it may be the alarm module or a problem with the door look.

morris374

yea its my door lock... alarm doesn't go off when i open the car with the trunk but ill unhook the module just because opening the car by using the trunk EVERY time is really annoying