HELP!!! '91 420SEL: Out of 6 month storage &.... - PeachParts Mercedes-Benz Forum

STORMINORMAN · #1 05-19-2007, 10:42 PM

...started up just fine. Drove it around a while, SRS light came on & stayed on!!!

Didn't think much of it: had the air pressure in the tires checked, parked & opened the hood. Car still unlocked.

Alarm went off.

Alarm turns off (as it is supposed to) with unlock/lock action in driver's door, passenger's door &/or trunk. Unlock driver's door and enter car... Then the alarm comes on again once key is turned, brake pedal is touched, any door opened, hood opened or trunk opened. Drove home with 60 seconds of horn, 30 seconds of lights flashing ONLY & 60 more seconds of horn: was nice and quiet for a while on the highway until I had to put on the brakes to exit.

Read plenty among the 450 or so SEARCH threads for "alarm system": almost the same amount for "SRS".

Thought battery might be culprit: checked battery, and it seemed fine... I then replaced it with a known good, fully charged battery & everything really seemed fine: alternator putting out 13-14v across battery terminals when running at idle. Solid 12v when not running. Drove around. Stopped a couple times & locked the car and returned, left the car unlocked a couple times: no problem.

Then, just making a right turn after driving for 5 or so minutes the alarm

comes on, again. And again, et cetera, ad nauseum.

Lock system seems ok. Everything opens and closes with the key in driver's door or passenger's door. TRUNK HAS THE DECAL THAT SAYS IT WILL ALSO LOCK & UNLOCK THE DOORS BUT IT HAS NEVER DONE THAT TO MY KNOWLEDGE. Door open switches (the black ones) all seem to be exactly the same, front & rear & hood and all seem to be working ok, too.

Can it REALLY just be the micro switches in the door handle locks that is causing this problem? Is there a cure besides pulling the connectors to the alarm control module and giving up? Should a good shop (or, God forbid, a Dealership

) be able to tell if an alarm module is still good?

According to the Buy Parts connection on this site this is the same $400+ controller P/N P2094-106377 as is used in the '88, which BTW only has one airbag vs. the two in the '91. I find this pretty strange: never had a single problem with either the SRS or the alarm in the last 5 years: maybe once the wife unlocked the driver's door through an open window but the alarm went off (& STAYED OFF!) once the unlock/lock cycle was done.

Car was stored outside 6 months or so under a really good car cover with a tarp on top to boot!

All your expertise and consideration is most appreciated. I'm

'in out!

just-n-time · #2 05-20-2007, 08:30 PM

The alarm may be going off because of one lock not completly unlocking, in my wifes 420 it was the trunk,if I relock and unlock from there its fine.

david s poole · #3 05-21-2007, 09:59 AM

those cars would develop a prob when car not used.usual cure is to cycle the locks from each of the three points on the car.if still probs go to the module in front under pass feet and disconnect both plugs for ten mins and repeat above procedure.

STORMINORMAN · #4 05-21-2007, 10:00 PM

Wow! I'll try that this week!

Thanks!