Let me first say that since becoming a member, iam not impressed with this forum. Iam not trying to offend anyone, iam just being truthful and i think everyone needs to assist members in any way they can and make a person feel welcomed, thats the whole point of the forum. I use to own a cadillac and i was a member of the Cadillac forum. Those brothers, not only answered and assisted me immediately with anything i asked, but alot of those brothers also sent me a big welcome when i first joined. I joined the mercedes forum 3 weeks ago, i immediately posted a question about my mercedes that i needed assistance with. Its been three weeks and not one suggestion or answer yet!!....... I have another question, i hope that someone gives me some advice this time. Thanks. Ok, I have a 2000 S430 and i've noticed that when i get home at night and lock my doors with my key pad, by the next morning my battery is dead and i have to jump the car, but if i do not lock the doors at night, the next morning everything is fine & the car starts right up, its obvious that when i lock the doors something is draining my battery overnight. Can anyone please offer some insite as to why this is happening or what could be going on? Thanks

 

I usually don't respond unless I am 100% sure my answer is correct and not being a mechanic my answers are usually wrong but my guess would be a short in the alarm as once the doors lock they don't need any juice but the alarm is just starting to draw.Hope this helps.

 

Not much to go on, this cars have a lot of equipment that it is powered even when the car is off. For starter, are you having any suspensions issues? reason to ask is that if you have a suspension issue the pump will keep the car level and drain the battery. Another issue maybe the soft closing hydraulic pump since you mention that only happened when you lock the car. If you provide more info maybe someone will chime in and help you. Trust me this cars have a lot and I mean a lot more technoloigy than Cadillac

 

By the way, have you done a load test in your battery? even is good enough to get going during the day may not be enough storage amps to power up in the morning