I have a 1997 E420 that sat for 5 years and I finally got it on the road and put about 2100 miles on it then left it sit two weeks and went to unlock it with the key cause I don't have a fob for the car and when I opened the door the alarm went off. I come to figure out that all the doors wasn't unlocking at the same time just the driver door so does that set the alarm off? Every since that you can drive the car but if you shut it off for 5 minutes then when you start it up the headlights, turn signals,wipers, door locks and some other things won't work But if I unhook the battery for 5 minutes and then start it back up everything works until it sits for 5 minutes! Does it have something to do with security system? Do I need a fob?