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I have a 2009 c300 that I just started having issues with.

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I have a 2009 c300...
I have a 2009 c300 that I just started having issues with . Left me stranded one day , then I got it started . Seemed to be dead like the battery was shot , replaced battery for the vehicle and battery in the key . Checked all fuses in the fuse box , all seemed to be fine . I'm getting a clicking sound from the "prefuse" box when opening the door . No power to ignition , Windows won't roll up or down , remote key lock and unlock won't work . Any help would be appreciated before I spend thousands at dealer
Submitted: 1 year ago.Category: Mercedes
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Answered in 22 hours by:
12/13/2015
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago
sprinkles08
sprinkles08, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 23,249
Experience: ASE Master and Advanced level certified. Factory trained with 17 years dealership experience
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Hello and welcome to JustAnswer!

If the vehicle is electrically dead then a power distribution, battery or cable/connection issue are likely. If it's just items that need the key to be on to operate that won't work then you may have an electronic ignition switch issue.

It appears that the battery was replaced previous to the current issue, if that's the case then the battery may be dead now. When was the battery replaced opposed to the current no start situation?

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Customer reply replied 1 year ago
Battery was replaced earlier this year , I have power to radio and interior lights , when I open the door I hear the prefuse box make a loud click.
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

Have you tried a jump start?

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Customer reply replied 1 year ago
I have tried to jump start , didn't seem to make a bit of a diference . I can go out and try another battery I have an optima red top o can try on it
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

If you have a second battery to try that would be great.

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Customer reply replied 1 year ago
Yeah I will go do that now and let you know the outcome so we can go from there
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

Ok.

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Customer reply replied 1 year ago
Ok switched battery nothing changes , just getting a single click out of the pre fuse box no power to ignition , only thing that works is radio and odometer will light up when door opens
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

Does keyless entry work?

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Customer reply replied 1 year ago
No keyless entry doesn't work . I took a couple videos but won't let me send them through this site
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

Do you have a big chain parts store such as Autozone?

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Customer reply replied 1 year ago
I do right up the road not even 5 minutes awy
Customer reply replied 1 year ago
Here's a list of fuses with power and without ... With power / 1,2,3,11,12,13,14,15,16,17,18,19,20,26,27,28,31,32... Without power 4,5,6,7,8,9,10,21,22,23,24,25,29,30,33,34 . This is all from main fuse box under the hood
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

I believe the problem is most likely with the electronic ignition switch but without having a full capability scan tool there isn't' a way to diagnose it properly, and a scan tool would be needed for the repair either way. It's possible that the key is the issue and while they wouldn't be able to tell anything about the transponder, an Autozone would be able to test the key fob's keyless entry output for free. If the fob wasn't transmitting then you know for sure it will need to be replaced. Again to program a replacement fob though it's going to require a dealer level scan tool.

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Customer reply replied 1 year ago
With the eis failure shouldn't I still get some sort of power to the dash still and get a Error message ?
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

Not if it isn't registering that the key has been turned to the run position.

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Customer reply replied 1 year ago
What do you think the clicking sound when i open the door and the power gets transferred though the junction box is .
Customer reply replied 1 year ago
I have power to all four post on the junction box when I open the door , if I close the door and wait for a couple minutes I only have power to the two bigger post
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

It's most likely an internal relay, I wouldn't be concerned with it.

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Customer reply replied 1 year ago
a this point you wouldn't think it was a power issue
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

Not if the battery has been replaced with a known good one and the cables are clean and tight.

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Customer reply replied 1 year ago
Yeah the battery is fine and connections are clean and tight , just find it weird the power to the key seems like it's non existent .
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

It's not weird at all. If the switch isn't working then it could just as well be unplugged.

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Customer reply replied 1 year ago
The key fob is transmitting a signal I went to the auto store and checked .
Mercedes Mechanic: sprinkles08, ASE Certified Technician replied 1 year ago

If RKE was lost at exactly the same time the starting problem started then odds are the key is ok if it's transmitting.

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