Where to Connect Power Wire for the Trailer Wiring Harness # 119192

Question:

Question 1: There are 2 thick wires comes to fuse box from battery - positve one and negative one as shown in the attached picture. What is the differnce it makes, if I connect the black power wire from PART #119192 to this positive wire already bolted in the fuse box VERSUS Connecting the black power wire from PART #119192 to the main Battery itself. Question 2: The website etrailer.com mentioned that PART #119192 is not compatible with 2014 ML350. Is that TRUE ?

asked by: Doss

Expert Reply:

The power wire of the trailer wiring harness part # 119192 that you bought needs to connect directly to the positive battery terminal of the battery in your vehicle.

It's purpose is to draw power directly from the vehicle battery for the trailer lights bypassing the vehicle's delicate wiring. If you were to power it from a fuse box like what you mentioned you'd not get the circuit protection and you'd void the warranty.

expert reply by: Jameson C

click to enlarge

Doss

10/12/2017

Jameson C.

10/12/2017

If you can verify that the power wire you found that runs to your fuse box comes directly from the vehicle battery then it wouldn't be any different to use that for the power wire of the harness. The # 119192 is a universal style of wiring harness that doesn't have a specific fit list for most applications. If you follow the instructions for it you'd be able to install it on your 2014 ML350. We recommend the part # 119250KIT more for your vehicle as it uses sensors to tap into the taillight wiring instead of needing to splice into them.