On my 1995 s420 I replaced my dead battery with a new one. Installation was fine but the alarm goes off and I can not turn it off without disconnecting the battery. Owners manual does not help. Any help will be appreciated.

the square key inserted into the driver's door and unlock the door should shut off the alarm.
if you wish to disable it, 124's have a panel under the front passenger's floormat. the alarm computer is in there, not sure if the 140's are the same...

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Is that a 1995 S420 W140 chassis OR is it a 2000 or later S430 W220 chassis??

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
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1995 is the 140 chassis.

Using a key in either front door OR in the deck lid should cancel the alarm.

Using the remote should always cancel the alarm.

If not, most likelt the control unit is bad. Disconnect it

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator