Trailer lights

Jerrell roy.

New member
I have 2018 Sprinter motor home. I blew a fuse under sprinter seat to trailer (jeep). Replaced fuse and checked all fuses but no lights. Installed new outlet and new whip. I plug in the tester light to seven blade outlet and everything shows good. Signal lights, brake lights, tail lights all show to be working but plug in the new connector and nothing tests out with test light. I am at the end of my wits.


Erratic Member
The Sprinter tests the trailer circuits (even when off) ... if it doesn't think you have a trailer attached, it doesn't power some of the lights (such as tail lights).
If you have LEDs on your trailer the Sprinter doesn't see them as "there"
(yes, i know it's a Jeep ... but what are you using as "trailer lights"?)

The Sprinter's trailer module works from one (or two) fuses ... ((i don't have 2018 diagrams, only 2007)).

2007 info (but woefully out-of-date by 2018) <-2007 MB service manual <- MB wiring diagram from above <-- 3rd party wiring diagrams

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