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Help: Wiring a harness for a trailer

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Finally got my wires identified for the trailer harness:

My VIN 43848 2014 MS trailer wiring colors were:
Trailer green to MS right flasher/brake blue/pink (snaked thru rear carpet channel)
Trailer yellow to MS left flasher/brake purple/green
Trailer brown to MS tail light purple/gray
Trailer White to MS chassis or Black

You may have to keep daytime running lights or headlights on for proper operation.
 
There are a number of web sites which list the Tekonsha trailer wiring kits as being appropriate for the Model S. For some examples see the following:

Reese-Hitches.com | Trailer Hitches & Towing Accessories | 877-507-0711
https://www.etrailer.com/Custom-Fit-Vehicle-Wiring/Tekonsha/119250KIT.html
http://www.tekonsha.com/fit-guides/electrical-selector
http://www.hiddenhitch.com/fit-guides/hitch-selector

I have exhaustively tested out the Tekonsha Universal Trailer Wiring Light Kit Harness Kit Plug (Splice) and have been unable to get it to work properly when the tail lights are turned off (consistent with the comments above). Has anyone tested the Zero Contact Interface Universal ModuLite from Tekonsha (referred to in a number off the websites)? If so, does it work properly?

For reference purposes the following are the relevant wire colors in our 2012 Model S:
upload_2018-1-4_23-39-51.png


Based on my testing each of the alternative turn signal wires on each side functioned in the same way.

Any insights would be appreciated.

Thanks.
 
All, for everyone installing trailer hitch. please read this article, dont want your car suffering from this metal rust, and aluminum deterioration.

Tesla Model S hitch by Torklift (3 year update): Eaten alive

That is actually quite horrifying. Galvanic corrosion is something I've worried a lot about since I basically drive in a salt bath for many months a year. I've had my fair share of rotted and corroded components replaced under warranty by Tesla, but mostly cosmetic. I do worry about some major component failing due to this process.
 
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That is actually quite horrifying. Galvanic corrosion is something I've worried a lot about since I basically drive in a salt bath for many months a year. I've had my fair share of rotted and corroded components replaced under warranty by Tesla, but mostly cosmetic. I do worry about some major component failing due to this process.

Thanks Mike,

I had seen the same report and had addressed the issue by isolating the steel from aluminum components with rubber spacers, use of stainless hardware, wherever possible and liberal use of Krown rustproofing. (I had my Model S treated with Krown when I purchased it.)

I recently took apart the rear bumper assembly of my five year old Model S and was pleased to find that there was not any significant corrosion, even on the Tesla steel bumper component which is bolted directly to the aluminum body. (When I reassembled it, I isolated the steel and aluminum components with stainless steel and rubber washers and treated liberally with Krown.)

A couple of small studs holding the bottom panels had failed and were replaced with stainless, but apart from those, all other fasteners were operable and in good condition. Overall, the rear end sheet metal and components were in better condition than I had feared they would be (based on reports such as the one you referred to).
 
MODEL S TRAILER WIRING PROBLEM SOLVED

There are a number of web sites which list the Tekonsha trailer wiring kits as being appropriate for the Model S. For some examples see the following:

Reese-Hitches.com | Trailer Hitches & Towing Accessories | 877-507-0711
https://www.etrailer.com/Custom-Fit-Vehicle-Wiring/Tekonsha/119250KIT.html
http://www.tekonsha.com/fit-guides/electrical-selector
http://www.hiddenhitch.com/fit-guides/hitch-selector

I have exhaustively tested out the Tekonsha Universal Trailer Wiring Light Kit Harness Kit Plug (Splice) and have been unable to get it to work properly when the tail lights are turned off (consistent with the comments above). Has anyone tested the Zero Contact Interface Universal ModuLite from Tekonsha (referred to in a number off the websites)? If so, does it work properly?

For reference purposes the following are the relevant wire colors in our 2012 Model S:
View attachment 271118

Based on my testing each of the alternative turn signal wires on each side functioned in the same way.

Any insights would be appreciated.

Thanks.

After further consideration I surmised that the trailer tail light circuit needed to combine the signals from both the left and the right tail light signals (see chart in my previous post) in a logical "AND" circuit (where the left and the right tail light circuits both needed to be powered in order for the trailer tail lights to be powered).

I implemented this using a simple low power 12 VDC relay where the left tail light circuit powered the coil of the relay and the switched the signal from the right tail light circuit. This simple circuit eliminates the problems with the use of trailer lights without needing to turn on the running lights or parking lights. The coil on the relay that I used has a resistance of 1200 ohms and therefore draws only around 10 milliamps when the tail light circuit is on and the circuit isolator draws only a few milliamps to switch on the tail lights (which are powered by the isolator directly from the car's 12 volt system).

The same fix may be used either with a circuit isolator (such as the Tekonsha Product Code: 119191-22, which is rated for up to 4.2 amps for turns/stops circuits and 7.5 amps for the tail light circuit and may be used with incandescent trailer bulbs) or for direct connection to a trailer with low power LED bulbs. (I am using the Tekonsha device to protect the Model S wiring from any problems or potential short circuits in the trailer wiring and to enable the use of some small incandescent lights on my hitch mount bike carrier.)
 
I just tried this on my 2013 MS and it bench tested great. Ready to get my 5x8 mesh trailer now. This was exactly what I was waiting for and the eco hitch is also great. Thanks for all your help BIGLY!!
I picked up the EcoHitch for the Model S and I need to get the harness wired in for the trailer lights. This is a light duty open motorcyle trailer that only needs rear lights and turn signals.

What I can't get a good answer to is wiring the car up for the trailer:
1. For a basic flat four wiring setup do I actually need a power source other than pulling power off of the existing lines from the tail lights?
2. If I do need a power source, I plan to fuse it, but where do I tap to get power on the Model S? Typically I would tap off of the battery of the car at the posts. I am not looking forward to digging the 12V out and tapping that since it is already a troublesome part on the MS.

My assumptions:

- Standard wiring harnesses pull power from the rear tail lamps to power the trailer lights
- Advanced wiring harnesses use a power block which is powered from a 12V power source to power the lights bypassing the use of the rear lamp power.

Any help is appreciated
Please correct me if I am wrong.
Not a big deal I hooked it up last year , go with all led . I'm more concerned about the differentiation metals . Having mine re and re with a washer kit in a couple weeks
 
Has anyone tested the Zero Contact Interface Universal ModuLite from Tekonsha (referred to in a number off the websites)? If so, does it work properly?

I went down the Zero Contact route. As I'm in Europe I also needed to hook up an extra converter to get a dedicated stop signal. Indicators work well so far, rear/running only on the right hand side of the trailer, stop not at all, if hazards are on, suddenly both rear/running lights run as hazards. So still some work to do.

I used the permanent 12V from the OBD port. Will have to troubleshoot next weekend.
 
After troubleshooting my setup I realised I had mixed up a Tesla wire and had also missed a connection on my trailer connector. So all is workin 100% now. The Tekonsha Zero Contact box is definitely the best option. I power it from the permanent 12V coming from the OBD2 port.
 
After troubleshooting my setup I realised I had mixed up a Tesla wire and had also missed a connection on my trailer connector. So all is workin 100% now. The Tekonsha Zero Contact box is definitely the best option. I power it from the permanent 12V coming from the OBD2 port.


I just purchased an EcoHitch and Tekonsha for my ‘13 Model S and am wondering where the OBD2 port is for the 12v? Any other locations near the back of the vehicle that I can tap into?
 
Has there been any updates on trailer use /new wiring/ use with filament bulbs / range etc? I'm hooking on a hitch for small in frequent use
I have been carrying 4 kayaks on the roof rack of my MS. They kill range by a lot. Since its so speed dependent, I can't give one number of how much they affected range, but at ~60mph at sea level/70 degrees temperature, probably 25% degradation in range. That is with them on the roof.

I got a Malone trailer and believe it or not, at those same conditions, I did not notice any degradation in range when the trailer is empty. Essentially, no effect. Wow. There must be some, maybe a few %, but not reliably measurable.

Next test is to put all 4 boats on the trailer. But I predict less reduction in range than putting them on the roof rack. Essentially they just drag along behind the car happily.
 
I have wired my harness according to what I read here for my 2012 MS:
  • Driver side purple+gray --> brown for the trailer running lights
  • Driver side purple --> yellow for the left turn/brake
  • Passenger side tan+black --> green for the right turn/brake
It all works pretty well except these issues:
  • The purple+gray light blinks when the turn signal blinks so the trailer running lights blink when I make a left turn. Its OK. I could just pick up both sides running lights separately and run them to the trailer and let the left side running lights blink when I turn left and the right side running lights blink when I turn right.
  • The clicking sound inside the car is gone when the trailer is plugged in. I see the lights on the display screen in front of the driver so I know the lights are working. But it's disconcerting. Is it probable I am doing something wrong? I saw some other wiring suggestions but am hesitant to open it all up again.
Thanks!