Taping into the dome light to get 12 volts USB

Fgauthier

New member
Does anyone have a clean solution to provide 2A USB power from the dome light? Trying to power a few accessories in a clean solution

Thanks

Francois
RB Components 2018 Sprinter 170 4x4 Ext.
 

sparkplug

Active member
I looked at mine and then read about all the people who struggle to even get the dome lights to work correctly without messing around with them and decided this was probably not going to be a good source.

I don't use the power outlet in the slide out cup holder so my plan is to run a wire off the back of that and route it up through the dash.

You could easily run it up the A pillar and into the headliner.

A lot more panels to be removed for sure, but I think a better and more reliable solution long term.
 
Best is to use a fuse tap and tap into one of the reserve sockets under the driver's seat. There are reserve sockets in that fuse block that are active when the key is on and the engine is off. The fuse block under the driver seat is intended to be used for build outs.
 

Aqua Puttana

Poly - Thread Finder
Does anyone have a clean solution to provide 2A USB power from the dome light? Trying to power a few accessories in a clean solution

Thanks

Francois
RB Components 2018 Sprinter 170 4x4 Ext.
Reports are that the NCV3 interior lamps have a local constant 12+ volt source. It may be necessary to establish a constant ground. A simple sheet metal screw into a support rib could supply that... not up into the roof. :tongue:

The USB 5 volt units I used have a bit of drain even with nothing plugged in so I included an on/off switch.

Tapping the T1N interior light circuit for the low loading of USB units has worked great for me. Some info for my T1N installs is here. It may give you some ideas for your NCV3.

Hack in USB Charging
https://sprinter-source.com/forum/showthread.php?p=762532#post762532

:cheers: vic
 

Fgauthier

New member
Thanks all for your answer. I think I will rebound from the dash and A-Pilar and avoid taping the dome light.

Regards
 

manwithgun

Active member
I second all of the info posted by Aqua above. The RED wire on the NCV3 dome light is a constant +12vdc that is fused. This can be spliced/tapped to source power. By then creating your own ground point to serve as the negative, you pretty much isolate the usb load from the BCM that “controls” the dome light switching function. If there are any solid brown wires in the headliner, this would likely be a factory grounding point that can also be used. Add your own switch to open and close either the positive + (red) or negative wires feeding the USB port since most that I have used are internally illuminated.

I have used these for compact switches where space is limited, and their larger big brother when space allows. https://www.amazon.com/gp/product/B07F9K3F82/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

https://www.amazon.com/stores/node/...owse-bin=Ulincos&ref_=bl_dp_s_web_19858731011
 

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