Alarm lights flashing

RENEE L

ADMIN
2004 MERCEDES BENZ C230
1.8L
4 CYL
2WD
AUTOMATIC
165,000 MILES

When I park my car the fog and tail lights blink on their own. I used my fob to unlock and lock the doors and a few seconds later the fog lights start blinking again. This is an intermittent problem and hard to replicate. Any advise would be greatly appreciated. I uploaded a video showing the problem.

Video (Click to make bigger)

Tuesday, November 7th, 2017 AT 3:10 PM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
51,603 POSTS

Hello,

On these cars the alarm goes off without the siren when the siren battery goes out. Mercedes decided they need a separate battery for their alarm horn and when it goes out the lights flash, it means it needs to be replaced. In most Mercedes the alarm horn is located in the passenger's side front wheel well behind the fender liner.

You will need to remove the wheel.

https://www.2carpros.com/articles/wheel-removal-and-re-installation

Below is a diagram. I included a picture of the unit apart showing the bad batteries.

Please let us know what happens.

Cheers, Ken

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