Using the rain sensor connector to power a dashcam?
Thread Starter
Newbie
Joined: Aug 2017
Posts: 10
Likes: 0
GLK
Using the rain sensor connector to power a dashcam?
Attempting to install a dashcam and was wondering if i can cut a USB cable and connect it to the rain sensor plug to draw power? If so, which cable should connect to where? Can i safely draw power from the rain sensor (please see pics below)
Thanks!
https://ibb.co/ifz84v
https://ibb.co/bDdPcF
If that can't be done, I'll have to run the USB cable all the way to the cigarette lighter which won't be really practical.
Thanks!
https://ibb.co/ifz84v
https://ibb.co/bDdPcF
If that can't be done, I'll have to run the USB cable all the way to the cigarette lighter which won't be really practical.
Super Member
Joined: Oct 2014
Posts: 701
Likes: 103
From: Ontario, Canada
2009 C63 AMG, 2010 C250 4Matic Sport
Do you have a 12v outlet in the glove box? It'd be easier to run a cable along the roof and down the A-pillar into the glove box. If you do I can take a picture of my setup for the basic idea.
I thought about doing something similar to what you're thinking but I remember deciding there were no "good" sources of 12v power available around that area
I thought about doing something similar to what you're thinking but I remember deciding there were no "good" sources of 12v power available around that area
Super Member
Joined: Jan 2009
Posts: 929
Likes: 51
From: Silicon Valley, California
Factory ordered 2012 MB C350 w/Dynamic Handling Package
Attempting to install a dashcam and was wondering if i can cut a USB cable and connect it to the rain sensor plug to draw power? If so, which cable should connect to where? Can i safely draw power from the rain sensor (please see pics below)
Thanks!
https://ibb.co/ifz84v
https://ibb.co/bDdPcF
If that can't be done, I'll have to run the USB cable all the way to the cigarette lighter which won't be really practical.
Thanks!
https://ibb.co/ifz84v
https://ibb.co/bDdPcF
If that can't be done, I'll have to run the USB cable all the way to the cigarette lighter which won't be really practical.
That's exactly what I did the 1st time. Worked flawlessly....UNTIL I had my windshield replaced, and the installer (trying to be nice) attempted to reinstall the wire and blew a fuse, causing the AC to go bonkers. After getting it repaired (found blown fuse) I tapped into the overhead console instead (more room to work, plus I was a little gun shy touching the rain sensor again).
Thread Starter
Newbie
Joined: Aug 2017
Posts: 10
Likes: 0
GLK
Good to know thanks , so which wire should connect to where based on the pic? My guess will be the red from the USB to the red from the rain absorption and the black from the USB to the brown from the sensor, is that correct?
Thread Starter
Newbie
Joined: Aug 2017
Posts: 10
Likes: 0
GLK
Do you have a 12v outlet in the glove box? It'd be easier to run a cable along the roof and down the A-pillar into the glove box. If you do I can take a picture of my setup for the basic idea.
I thought about doing something similar to what you're thinking but I remember deciding there were no "good" sources of 12v power available around that area
I thought about doing something similar to what you're thinking but I remember deciding there were no "good" sources of 12v power available around that area
Super Member
Joined: Aug 2011
Posts: 861
Likes: 38
From: Philly area
350 GLK, C280
If you use any of the systems up in the top of the windshield , you run the risk of blowing an output transistor in the processor. Even the lights are controlled through outputs in the processor not by switches to ground as in the old car systems. This means that the switches are very low power processor inputs so the wires can be small. You must have a cigarette lighter somewhere up front. Run the power from there.
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Thread Starter
Newbie
Joined: Aug 2017
Posts: 10
Likes: 0
GLK
Thank you for the info, I was also considering using the USB port in the middle console but couldn't find an easy way to run a wire inside that console. There is what looks like an empty switch next to the USB port but I couldn't remove/open the cover. How difficult it is to remove that entire middle section so that i can drill a hole in cleanly?
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Newbie
Joined: Jan 2026
Posts: 1
Likes: 0
2009 E350 Coupe C207
Attempting to install a dashcam and was wondering if i can cut a USB cable and connect it to the rain sensor plug to draw power? If so, which cable should connect to where? Can i safely draw power from the rain sensor (please see pics below)
Thanks!
https://ibb.co/ifz84v
https://ibb.co/bDdPcF
If that can't be done, I'll have to run the USB cable all the way to the cigarette lighter which won't be really practical.
Thanks!
https://ibb.co/ifz84v
https://ibb.co/bDdPcF
If that can't be done, I'll have to run the USB cable all the way to the cigarette lighter which won't be really practical.
Last edited by Phil Botha; Jan 27, 2026 at 07:48 AM. Reason: more info
