Uchi

Hey guys,

Have come to the forum to ask for help and ideas.
So I left the key in my 09 w211 e350 for 2 days. Just in the ignition, not turned around at all.

So I tried to start it today but no luck. All dash lights worked and no battery warning. No warnings at all.

No ignition, no click, but the wheel lock did disengage. Parking lights still worked but no main or hi beams. So I figured dead battery. Went to jump start it from the terminals in the boot.

I made a mistake and jump started it from the boot battery directly. The boot battery had the green color on the indicator window, so I do not think I needed to jump it.

I tried to start it a few times during the jump. The dash lights worked but again, no ignition at all. I then disconnected the battery negative terminal first and reconnected. Now there are no dash lights or door lights at all and the steering lock won't disengage to start the car.

I checked the fuses in the boot opposite the battery and they show no indication of being blown.

Any ideas?

Going to the dealership is a last resort in Qatar because it is stupid expensive.

​​​​​​​To recap, battery seems ok with a green indicator on the window. It's less than 4yrs old. Dash lights would show and no error indication on the dash but car wouldn't start. Jump started from boot, dash lights still worked but no ignition when I turned the key. Disconnected battery and now no dash lights or door lights. Battery fuses ok.

Thanks guys

bbirdwell

Key fob should never be in ignition when disconnecting/connecting the main battery. If keyless-go, key fob must be at least 2 meters away from the car to prevent energizing the circuits. Connect battery or jumper cables, then insert key fob. Proper technique here:
https://mbworld.org/forums/w212-amg/...ml#post7798479

You're going to have to inspect every fuse in the car; I know of one person who blew five fuses in his car when he went to jump-start it with the key fob in the ignition. Hopefully that is all that is wrong with yours.
https://mbworld.org/forums/e-class-w...les-chart.html

When in doubt about battery voltage, bring the bus voltage up on the instrument cluster while key fob is in position 1.

If all fuses are good, then you're going to need power to the system and the ability to turn the key fob to position 2 to scan for faulty modules. If the key won't turn, you're looking at calling in the professionals for major work up to and including removal/replacement of the EIS and/or other modules.

Uchi

Oh dear! Right so I'll start by checking all the fuses visually for evidence of melting.

The big ones look ok, so I will go through and check the small ones that are under the hood.

I still don't understand why it didn't start before i jump started it. There was no battery warning and all lights worked except the main headlights.

Presumably I should get a battery charger and fully charge the battery disconnected from the car after I've checked all the fuses?

Don't ever work on a car when angry I guess! 😆

Thanks for your help.

Uchi

Ok so I found a 15A blown fuse under the bonnet and replaced it. Charged the battery. It started at 6V but after some charge it went up to 13V.

Got the car started 👍👍 no issues.

However, the next day the car would not start.

Keep in mind the battery is 2-3yrs old in a hot climate of Qatar, but the indicator window is still green meaning ok fluid levels.
I charged it for about 12hrs, it shouldn't be dead after sitting overnight?

Seeing the battery dead after the keys were left in it, the chances of a parasitic draw are low correct? Would have happened before.

Cheers guys, your help saved me a lot of hassle!

bbirdwell

Glad to hear you found the problem and got the car started. Based upon your description, I would say your main battery is no longer sufficient for the car (remember, approximately 32 digital modules in your car). Bring the bus voltage up on the instrument cluster (key position 1, wrench or speedometer on cluster display, push reset button on left side 3 times within one second; voltage should appear) and verify with engine off and running.

FWIW, when my battery would read 12.1 volts with engine off, my car would fail to start even after trickle charging overnight. South Texas is not as hot as Qatar but my battery only lasted a little over three years before it failed. The battery still tested strong with a battery tester, but would not start the car.

Uchi

I don't think I connected it properly when I put it back in... Car sat for a week and interior lights switched back on when I went to untighten the battery. Which wasn't properly tightened anyway.

Just bought a new battery too. Voltage showing 12.1v on the dash.

Yeah I should probably replace it, but still. 😆