JPetros2008

I should maybe preface this by saying that I have a 2008 C63 with about 76k miles.

The past month or so, my car has been acting funny regarding the electrical components somewhere. I'm obviously not sure what's going on so I reaaaaally hope someone can give me an idea.


Basically what happens is from time to time (maybe 1 out of 50) or something times I try to start my car, I turn the key and nothing happens. Like the car doesn't even register that the key was ever put into the car. I have to take the key out and then put it back in and it reads the key is there and the car starts. I don't know that this is related, but I have a feeling it may be.


One time I got to the mall (the night before Christmas Eve) and there was literally NO parking. I finally saw an open spot, but the guys the mall had hired to direct traffic in the parking garages told me that it was for hybrid vehicles only. I pointed to my 6.3 AMG badge on the side of my car and told them this was indeed a hybrid vehicle and it worked. I was chuckling to myself and as I was turning off my car and rolling up my window, everything just stopped. The navigation screen stopped going down like halfway through, the window was halfway down still, and the car wouldn't respond to anything. I tried putting the key in and taking it out multiple times, but it wouldn't register at all. I tried pressing all the buttons on the key, but while the little red light would come on on the key, the car wouldn't register it at all. It's like the battery completely died or something. Anyway, I sat there for like 10 minutes thinking about how this was instant Karma for trying to park in this hybrid spot with the most unholy of cars. Finally I gave it another shot and out of nowhere, the car registered the key and the navigation went down and came back up as if I was about to start the car. Car ran fine after that.

A couple weeks later, I get home and put my car in the garage. I get upstairs and start changing my clothes when I hear my alarm going off. I figure I accidentally pressed the alarm button on the key so I try to press it again to turn it off, but the alarm keeps going. I go downstairs and it still won't work. I'm like ok, let me try to open the car and put the key in and that should stop it. I'm pressing unlock on the key, but it won't unlock the door at all. I take the metal key out and open the door manually and stick the key in the ignition but once again, it's not registering that the key is in there or something all while the alarm is going off. I'm thinking wtf am I supposed to do now. I figure I can open the trunk and just disconnect the battery. As I'm getting up to quickly do that, the alarm suddenly stops. I put the key in and the car registers that it's in there. Everything works fine after that.

Now today, I got food on the way to a friend's house, but was finishing eating it outside his house. I turned the engine off and left the car playing music while I finished eating and reading stuff on my phone while sitting in my car. All of a sudden, everything turns off again. I'm thinking great....at least I'm in a better spot than a hybrid parking spot at the mall where I can potentially get towed. I try the key like 5 times, but it doesn't work at all so I just say screw it and go inside.

That's where I am now. I'm assuming that it'll work like normal when I go to try to start my car later tonight, but there's always a chance it won't. I tried to explain what's going on as best as I could remember, but it probably made it a very long, unnecessary read. I apologize for that, but hopefully I've given you guys enough information to help me figure out what's going on without taking it to the dealer. I'm assuming it's not something related to the key, but I do have a spare that I haven't tried using at all. I don't know if it's a battery issue or maybe a connection issue, but I'm hoping it's nothing expensive as my car is out of warranty. Either way, this is obviously a frustrating issue and I don't want this to happen while I'm driving or in a place where I absolutely can not have the car just sitting there stuck, because I can't move it.

Any ideas?

EkS

Have you had the car battery checked or replaced?

SaphGreyC63

have you had the key battery checked or replaced?

JPetros2008

I had the battery checked about 6 months ago when I got new tires. They said the battery was perfect. I guess it couldn't hurt to check it again though, but I just would assume it isn't the problem.

It absolutely can not be the battery in the key, because whenever I press a button on the key, the red light blinks. I've also had previous Mercedes with completely dead batteries that still can start the car. I don't think the actual key needs to have a battery to be able to start and operate a car. It just needs the battery to be able to open the door without taking the metal key out and sticking it into the keyhole in the door.

EkS

How old is the battery in the car?

JPetros2008

I actually bought the car used last April so I have no idea. I'll see if I can run to NTB and get them to test my battery.

JPetros2008

just tried to start the car and it wouldn't work.

opened the trunk and wiggled both the connecting cables on the battery to make sure they were tight. as i was putting the trunk mat back in place, the trunk lights and whatnot suddenly came on. tried to start the car and it started. ran back inside because it was sooooo cold. i'm assuming the car is good to go for now, but i'm going to open the trunk again tomorrow and see what was going on.

the cables seemed pretty tight so what could be the problem? at this point i'm pretty sure it's something with the connection to the battery. it can't be corrosion right? i'm assuming that doesn't happen when the battery is in the trunk? i can take pictures tomorrow if it'll help you guys help me.

khmergod

Christine. Name her Christine and tell her you love her.

BerBer63

Had to switch my battery, I got mine in 09

Roswell

Just replace your car battery first, and see if it does it again. I think it's safe to say it's the battery.

Definitely not the key battery cuz you can drive the car even with a dead key battery.. and the car should not turn off out of nowhere due to dead key battery.

Mikegpr03

Man I forgot about that movie!!!

m3equals333

def some electrical glitches in this car I think...two days ago the mode selector switch (C,S,S+,M,RS) suddenly stopped working when I started the car up after driving it for a couple hours with no problem. The car was stuck in C mode even the light on the selector switch was out. Only thing I could do was switch to Manual Mode in Comfort mode by hitting the shifter or paddle shifter. I shut off and restarted the car 3 times waiting a few minute in between to no avail. Finally I gave up went into my house and started it up an hour or two later and it was working again. Since then, it has been fine, but I am a bit sketched out by it. If anyone knows anything about this issue, I would appreciate it.

sorry to threadjack, but I figured it was close enough to the topic

JPetros2008

car's been running fine for the most part. tried to take it to get the battery checked, but they said it'd be about 2 hours. didn't feel like waiting so i left.

later, i went to start the car and it did the thing where it doesn't register the key is in the ignition. i had just unlocked the car using the remote. i tried it again and the car started, but the gas gauge was saying i had no gas at all even though i had just filled up the night before. i forgot to mention that the car does this periodically as well. don't know if it's related, but i'm almost certain it is. as i drove back home, the gas gauge eventually moved up a little from completely empty to just at the cusp of where the reserve light comes on. tank is still completely full though.

i'm going to get the battery tested this weekend, but just wanted to know if maybe someone had any additional insight.