560 SEL alarm issue at airport - PeachParts Mercedes-Benz Forum

cherry_560SEL · #1 01-25-2009, 03:15 AM

After a week of sitting at the airport, the 560 would not start. We got the shuttle driver to charge the battery and as soon as I turned the key the alarm went off. It would not go off no matter what I tried. I decided to just let the car charge while the alarm was going, and eventually it stopped. Now the doorlocks dont work automatically. Weird huh?!!? Why is this happening?

stevebfl · #2 01-25-2009, 11:25 AM

First, the MB alarm in your car will not keep the car from starting, except maybe by running the battery down. Th ealarm is set and disarmed via a switch in the door handle. There are switch of equal command in the front doors and the trunk. Verify proper control by trying all of them first as the drivers door logically is the first to fail as it is used 99+ % of the time.

The door handle imparts an action to the door lock which is connected to the lock actuator linkage which has the control of the lock system. Again each front door and trunk has the ability to operate this separate system. Try looking and unlocking at each before deciding what is and isn't working.

cherry_560SEL · #3 01-29-2009, 01:57 PM

The car starts fine. Its just that the door locks don't work automatically anymore. I can lock/unlock the doors with no problem. Also, ever since that night. The alarm does not go off when i open a unlocked door without the key. Before I could leave the window rolled down and open the door manually and the alarm would go off. Now, nothing. What gives???

pawoSD · #4 01-29-2009, 02:06 PM

Sounds like a potential bad alarm sensor/switch in the drivers door....or perhaps the whole system just went nuts. I'd probably just deactivate it if it was my car. 20 year old MB's aren't at the top of the list for most thieves. Especially since the key locks themselves are virtually tamper proof.

cherry_560SEL · #5 01-29-2009, 02:08 PM

I agree. I seems like it may be just draining my battery anyways. SO how would I go about disconnecting it? I noticed you have some 300SD's in your garage. Where is the block heater connection on these cars?

pawoSD · #6 01-29-2009, 02:10 PM

Usually its a black box on the passenger side somewhere, either under the carpet, or in the kick panel. I'm sure others will know where it is on a W126....I only know where it is on the W124..... I think the box usually says "Becker" on it....simply unplugging it kills the alarm system with no other issues.

cherry_560SEL · #7 01-29-2009, 02:13 PM

ok..I will check it out. Thanks for the help. Do you think this will bring the automatic door locks back?

pawoSD · #8 01-29-2009, 02:19 PM

The door locks is probably a bad switch or maybe the pump (in the trunk in the spare tire well) might have failed. If there is a vacuum leak somewhere in the car's locking system, the pump may have run continuously and fried itself...I've seen that happen before. Might also be what drained the battery perhaps?

cherry_560SEL · #9 02-06-2009, 04:35 PM

well...i got around to checking things out and I wasw delighted to see that the door-lock issue was just a blown fuse. apparently the doorlocks use the same fuse as the rear interior lamp as well as the door lights. I noticed my rear interior light was out and when i checked the fuse box it showed that the door locks were also on the same fuse. thank god i didnt go tearing out anything...lol....I also found the problems I was encountering (slow, sluggish starts...windshield wipers going nuts when I start the car) were caused by a bad battery that would not hold a charge. Glad I went and had the battery checked when i did or else i could be facing a bad alternator.

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