I have read the threads and have discovered there is a box under the passenger side floor mats that can be disconnected, but someone also said that there is a fuse holder next to the main fuse panel under the hood that has two 16A fuses in it that can also be removed to disable it more easily. This may be on the 1st generation W126, but not sure. I say that because when I raise the hood, I see a red wire from fuse box with a fuse holder, but it only has one fuse in it. Ours is a 1988 model. It did this about 4 years ago when it was my car (alarming when door was opened after being locked), then it stopped for about 3 years. Unfortunately, it recently started doing it again (the car is now my mothers) and this time the door was not even locked and had not been locked. My dad opened the BACK door to put in a child car seat and the alarm started blaring. It finally stopped then the other day I went to check it out, opened the door and it started blaring again... horns, lights, etc. Horn finally stopped, but the lights kept on, I had to finally disconnect the battery and that is how it is still setting.

Can anyone provide any additional information about the way to disable it from under the hood and any pics of what needs to be disconnected appreciated. Also, if I just go the route of disconnecting the box under the passenger floor mat, do I just leave the wire loose in there? I am not sure how the connector looks, but didnt know if disconnecting it left exposed live wires under there or not.

Thanks again!

I would venture by the time someone replies to the exact fuse location (or you look it up), you can just pull the floor mat and carpet pad, then pop the plastic cover off the alarm brain to unplug it. Really, you are talking a five minute job. Max.

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I did it the way Hit Man X mentioned.

Pull passenger mat, unplug brain.

I was told that you shouldn't unplug fuses to disable it, because there is more than one fuse. With something like this, you want it completely disabled.

For reference, I never noticed any side effects of having it disabled. The car worked perfectly normally after I unplugged it.

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Thanks for the replies guys... I will just remove the carpeting and do it from there. Thanks again.

Ok, I done it... I think. lol.

When I removed the panel against the front of the floor I seen what I think is the box, what I wasnt expecting however was not one plug, but two. There is also a big factory wire tie around the box to hold it in place and unless I cut it, I was unable to disconnect the bigger 2nd connector, so I only disconnected the one (see pic below) and it too had the wire tie around it, but I was at least able to disconnect it and pull it away a little. I am hoping it dont reconnect itself, but I dont think it will... This is what I unplugged, hope it was right. Also the alarm didnt sound when I hooked the battery back up, so that is a good sign.





When I was under there, I noticed something of concern, the floor pan was a little bit wet and there was some condensation under there and its not anti-freeze, its water. We have had TONS and I mean TONS of rain (about 15 inches of rain in 5 weeks), so its really been damp around here. My first thought was leaking heater core, but #1 we dont ever smell coolant and #2 I touched and smelled it and it was only water. The car had not been driven in a couple of weeks. I wonder if it could be caused from clogged A/C evaporator drain lines? I do know that when our A/C was working that no water even came out from under the car.

Check under the battery tray, W126's are notorious for the battery acid leaking and corroding the firewall.

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Thanks Mike, will check that out.

I sold my last W126 about 6 years ago, so I'm going from memory here....

I believe the small connector is the power/ground/etc connector. The larger one has the wires that go to door latch switches, trunk switch, etc. If you pull the small connector, you disable the entire system. No need to worry about the big connector as it just carries signals to/from the various locations.

Regarding the leak, has your windshield ever been replaced? A lot of times the seals leak (either through improper installation, or someone using an aftermarket rubber seal). The water then leaks into the car through the failed seal.

I would try taping a bunch of paper towels as high up the passenger floorboard as you can (get them right up against the metal) and then shut the car and hit the edges of the windshield with a garden hose on the highest 'jet' setting. Go all around the windshield edges, then open the car and see if there is any water on the paper towel.

It could be a battery leak, but it sounds like you have too much water for that.. Your battery would be too empty to start the car if it had leaked that much, in my opinion.

__________________
'83 300SD 335,000km (207k) mi SOLD
'87 560SL 163,000km (101k mi) SOLD
'86 300SDL 356,000km (220k mi) SOLD
'92 500SEL 250,000km (155k mi) SOLD
'90 300SL 140,000km (87k mi) SOLD
'01 S430 260,000km (161k mi) SOLD
'03 SL500 167,000km (104k mi) SOLD
'07 S550 4MATIC 235,000km (146k mi) SOLD
'07 GL320 CDI 4MATIC 348,000km (215k mi)
'13 GL350 BlueTec 4MATIC 170,000km (105k mi)
'14 SL550 72,000km (43k mi)

Thanks! Well I was thinking AND hoping that the smaller connector was the power supply and disconnecting that one alone would do the trick either way! I really didnt want to cut that factory tie and have that box dangling around down there.

Yeah, I will have to investigate that water, I didnt even know it was there, we had never removed that panel before. I dont think its been leaking long, as the floor is still like new under there and not rusty. I would imagine if water had been in there for a very long time, it would be rusty and of course from the outside underneath either, as its like new under there still yet.

Thanks again!