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Trailer Wiring Harness for 2017 Model S

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I bought a trailer hitch for my 12/2016 Model S and although it will be used 95% for my bike rack, I would still like to have wiring for my seldom-used trailer. I did a search here and found a number of posts on the topic BUT they were for model years pre-facelift and from what I could tell, wiring colors (and maybe even electronics) have changed.

In searching hitch sites, I did find a couple of 'kits' that were available for the 2017-2019 MS but they were ridiculous in price - one was over $200. I was hoping someone here with a newer MS might have successfully tackled this DIY project and be able to provide direction.

My trailer has a 4 pin connector with separate wires for right, left and parking lights. It has LED lights and I measured that the max current draw for brake lights plus running lights is only 350ma (turn signals are 130mA each [so for braking we are talking 2X that] and running lights 90mA).

The first question is whether there is something 'odd' about 2017+ vehicles in terms of wiring for the rear tail/brake lights (e.g. instead of single wires for parking lights, left turn and right turn they are doing something 'digital' on a wire pair).

If there is single wires for each, does anyone know the colors for each (past posts have shown the wire colors changed multiple times over the years)?

Lastly, if I do need some sort of 'isolation' device to separate the car from the trailer, do you know of an inexpensive generic one that isn't 1/2 the cost of the hitch :) ?

Thanks.

Thanks for any help.
 

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The Circuit Diagrams I have are:

Left-Hand Drive, Rear Wheel Drive
Start of Production through May 31, 2013
May 31, 2013 through January 6, 2014
January 6, 2014 through May 19, 2014 (without HVAC ionizer)
January 28, 2014 through July 11, 2014 (with HVAC ionizer)
July 11, 2014 through October 28, 2014
October 28, 2014 through Current Production

Left-Hand Drive, Dual Motor
All LHD Dual Motor

Right-Hand Drive, Rear Wheel Drive
Start of Production through July 9, 2014
July 9, 2014 through October 28, 2014
October 28, 2014 through Current Production

It looks like all Left-Hand Drive, Dual Motor are the same. The diagram I uploaded is from that file.
 
I bought a trailer hitch for my 12/2016 Model S and although it will be used 95% for my bike rack, I would still like to have wiring for my seldom-used trailer. I did a search here and found a number of posts on the topic BUT they were for model years pre-facelift and from what I could tell, wiring colors (and maybe even electronics) have changed.

In searching hitch sites, I did find a couple of 'kits' that were available for the 2017-2019 MS but they were ridiculous in price - one was over $200. I was hoping someone here with a newer MS might have successfully tackled this DIY project and be able to provide direction.

My trailer has a 4 pin connector with separate wires for right, left and parking lights. It has LED lights and I measured that the max current draw for brake lights plus running lights is only 350ma (turn signals are 130mA each [so for braking we are talking 2X that] and running lights 90mA).

The first question is whether there is something 'odd' about 2017+ vehicles in terms of wiring for the rear tail/brake lights (e.g. instead of single wires for parking lights, left turn and right turn they are doing something 'digital' on a wire pair).

If there is single wires for each, does anyone know the colors for each (past posts have shown the wire colors changed multiple times over the years)?

Lastly, if I do need some sort of 'isolation' device to separate the car from the trailer, do you know of an inexpensive generic one that isn't 1/2 the cost of the hitch :) ?

Thanks.

Thanks for any help.

I just finished installing my ecoHitch yesterday (5/16) and wired up the lights today. In my 2017 Tesla S 75D the wiring for the driver side lights were
  • red/purple = Tail
  • blue/red = Driver Side Turn Signal
  • White/Red = Stop
I got the passenger side right but I didn't write it down...sorry. I used the Tekonsha Wiring harness as well. I ran a wire to the battery terminal though and did not try finding rear constant 12V. My voltage is running 17V off battery.

Hope this helps,

Scott
 
@scottwsmiley
"My voltage is running 17V off battery" That seems really high. What type of 12V battery do you have?

SCOTT: That seems very high. Maybe your VOM needs calibration? I would be worried if it were above 15V...

LAURS: You can get +12V from the rear hatch power struts. That is where I connected to - saved having to run a wire all the way to the frunk. Easy to find as it is one of the few heavier gauge wires in the bundle. Sorry but I don't remember the color.

Also, one thing to check - I found that I have to keep my lights on in order for the left turn signal to work properly (or maybe it was the right???). In either case, one works correctly, the other makes BOTH left and right flash. Someone else I was talking to posted a circuit to prevent this (required an isolation relay, and some additional wiring) but I didn't want the additional wiring so I just remember to manually turn on the parking lights. You may want to check this once you do your install..

Good luck.
 
The Circuit Diagrams I have are:

Left-Hand Drive, Rear Wheel Drive
Start of Production through May 31, 2013
May 31, 2013 through January 6, 2014
January 6, 2014 through May 19, 2014 (without HVAC ionizer)
January 28, 2014 through July 11, 2014 (with HVAC ionizer)
July 11, 2014 through October 28, 2014
October 28, 2014 through Current Production

Left-Hand Drive, Dual Motor
All LHD Dual Motor

Right-Hand Drive, Rear Wheel Drive
Start of Production through July 9, 2014
July 9, 2014 through October 28, 2014
October 28, 2014 through Current Production

It looks like all Left-Hand Drive, Dual Motor are the same. The diagram I uploaded is from that file.

hello, good post, thanks. we have an early '12, would you be able to post your "Left-Hand Drive, Rear Wheel Drive Start of Production through May 31, 2013" tail light wiring diagram? have looked and see too many different answers on the color q. and would like to verify from correct diagram. thank you. ts2493
 
Gonna resurrect an old thread here because I can't get this thing to work. Here's a vid of what happens when I hit each light 🤦‍♂️
I've done the remove fuse and try again thing a dozen or more times with no luck.
Everything is hooked to the right wire according to the wiring diagram off the Tesla webpage for my year/month car.

I'm tempted to just do it the old fashioned way and splice into the wires because this new fangled crap with sensors and *sugar* just ain't working.

Any ideas?
 

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