Paul J C
 

Need to cancel factory alarm on 300 SDL. Can you help?

Too late, the car was delivered 18 years ago :)

You don't give symptoms of the problem but here's a couple of things you can try -

1) If the alarm sounds after you open the door even if you use the proper key, try unlocking from the other door or trunk, or unlock the door, open the door and quickly turn the key back to lock. The door won't lock and it won't matter because the door is open. Usually that turns off the alarm. If that works, the problem is a bad key switch. I think you need to replace the entire door handle assembly since the switch alone cannot be replaced.

2) Remove the fornt passenger carpet, remove the near vertical plastic panel (there's a 10mm head nut at the center bottom of the panel), locate the black slender box usually with Becker markings with two connectors with 12-14 pins each. Remove the connectors and you'll disable the alarm system.

This assumes the problem is with the factory alarm as you say. If the problem is instead with an aftermarket alarm, maybe added for remote keyless entry feature, these tips won't help.

Sixto
95 S420
87 300SDL