My friend has a 87 300D and his factory alarm is on and he can't turn it off other than to disconnect the battery. He hoped disconnecting and reconnecting the battery might recycle the system but that did not work. He does not have the original key for the car since the ignition switch was changed and does not have a plastic key which is mentioned in the owner's manual. Any idea on how to disable it or reset it with the info provided?

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99 E300 133K
98 ML320 99K
87 Saab 900 Turbo Conv 123K

I would disconnect the alarm module located under the floor mat and plastic under the front passenger side.

Can you be more specific about the location of the module? Is it under the floormat or under the dash portion of the passenger side?
Thanks.

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99 E300 133K
98 ML320 99K
87 Saab 900 Turbo Conv 123K

Looked under the floormat and plastic cover and only found a radio module and connections for the airbag. Disconnected the radio module but the alarm was still not disabled. Ideas?

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99 E300 133K
98 ML320 99K
87 Saab 900 Turbo Conv 123K

Sorry, I assumed they put that unit there in most cars . Maybe a 300d owner can locate it for you.