Hello everyone I have been a member since the mid-2000s and haven't been logged in since 2009 after I got rid of my E500.
I did have to make a new profile and I'm really needing some help the car is a 2010 S550 4matic.
having trouble with the car starting get in turn the key all the electronics come on when you go to turn the key nothing happens no clicks nothing happens at all battery is fully charged and all that is as it should be.
it's my father-in-law's car and he's older so I'm trying to help him out.
I'm not seeing any check engine lights or anything the car does not have keyless go it has a normal Laser Key and I have no idea what's going on I checked the relays and all of that and they seem to be in good working order like I said you turn the key and try to start it and nothing happens at all the key has new batteries in it as well.
please help I'm trying to save him some money and hassle of taking it to the dealer and then ripping him off please let me know thank you all so much.
konigstiger has help me a great deal in the past not shure if he is even active on here anymore but he was a great guy.

 

Also we did try giving it a jump from the battery under the hood and still nothing did have the battery test it at Pep Boys and it was 11.7 volts they said it was good but I'm not really trusting that but earlier that day car started and ran perfect

 

Fear not for He will sense this thread soon and aid ye

 

Okay just found a paper from the battery scanner it was at 12.3 volts

 

I'm having a simular issue. It could be your Electronic Ignition Switch (EIS) going bad. I took readings of my battery at 12v and it would not turn over at all, I had alot of messages on the screen. I then used a scanner and found alot of messages of no CAN comunication with the EIS control unit n73. I took out the battery, took it to Autozone, and they recharged it to 12.5 volts. When I installed it on the car it started right up. I have a feeling the EIS is going bad and got reset when I took off the battery. My car is in the shop right now getting looked at. Disconnect your battery for like a half hour, plug it back on, and see what happens. Also try your spare key, sometimes they lose the connection with your EIS unit.

 

Thanks for the reply and The Help haven't tried it yet going to in a little bit anyone else got any ideas if that don't work?

 

Pick up a scanner that can do MB codes and scan for codes. They're so cheap now, the Autel AP200 is only $63 on Amazon, no reason not to get one. Several other ones out there that are a bit more, iCarsoft, Bluedriver, Foxwell, Launch etc. Come back with the codes. As mentioned earlier, could be EIS, starter, relay, fuse, loose ground, etc. Scanning it will give you a clue where to look.

 

Probably just the starter, open the SAM/FUSE box unthreatening the hood. It’s on the left side of the of the engine bay. The starter wire is purple/white. Put 12v into in and see if the starter turns. It should even if the car is off... also you can test it when key is turned to the start position that wire should have 12v..