Stealth hitch install (wiring)

[Quorky]

Hi all,

Looking for some help here. Started the install on the Stealth hitch today. The hitch install itself is fairly easy and straight forward. The wiring I have a few questions.

So it seems that my car has the opening for the hitch below the bumper and also has the wiring harness as well (see pics)...

It looks like the hitch harness is some proprietary connector and a 3 connector adapter to the standard 3 + 1 ground wiring harness (but missing the +1 ground). There are no metal connectors inside the connector that looks to be the standard type but there but that is an easy solve to just remove the proprietary harness and slap on the new, standard one.

I am trying to find what wire does what, but just getting stable reading from the red and small yellow at 12-14volts. Blinkers don't translate into voltage variation and the black doesn't seem to do anything. Had my wife put the car in Drive and test blinkers, but not seeing differentiation (unless I am doing something wrong). Pretty sure the Red is constant voltage (even with car off, reading hot).

Anybody have some insight? I really don't wanna run the Stealth hitch wiring all the way to the front and tap into lights when everything seems to be already run for the car via factory.

Thanks.

 

[Quorky]

Pics

 

[Quorky]

More

 

[Puddles]

I had such trouble hooking up trailer lights, I gave up. Part of it was that Tesla uses some wonky PWM which won’t show up on a regular volt meter. The other part was the gossamer thin wiring I was terrified to tap into.

so, I’m no help to you, but I am very intrigued that you seem to have found a connector designed for this purpose. What month is your model 3? Where did you find this connector? Maybe I can retrofit my harness, if there has been a redesign. Maybe I have this connector and don’t know it.

 

[Quorky]

I had such trouble hooking up trailer lights, I gave up. Part of it was that Tesla uses some wonky PWM which won’t show up on a regular volt meter. The other part was the gossamer thin wiring I was terrified to tap into.

so, I’m no help to you, but I am very intrigued that you seem to have found a connector designed for this purpose. What month is your model 3? Where did you find this connector? Maybe I can retrofit my harness, if there has been a redesign. Maybe I have this connector and don’t know it.

1. So mine was born Sep 15th 2019
2. Connector was taped to the crash bar (the small connector is plugged into a control box, 4 wires going into it, you can see a closed up of it in the previous post and the hitch harness is spliced into that)
3. If Tesla uses a proprietary switch/harness, it still has to play nice with the industry standard harness. The standard hitch / small trailer should be just plug and play, unless Tesla meant for this to go into a Tesla trailer (obviously being silly on this one).

 

[Puddles]

Hum, mine was delivered late October 2018. I am thinking changes were made. Surely I woulda noticed such a connector, having the entire trunk apart for at least a month.

I’ll ask Tesla service about it the next time I’m granted an audience.

 

[Quorky]

yeah, def, think they added around mid 19' when they started the European / UK hitch offering. I just cant find any information on it at all. Even on the UK side... zero info.

so my question is, do i need to run the hot to the 12 volt upfront if all of the wiring is already back there? why even run the 12v constant if all the wiring is available back there (even on the old models via tail lights)?

 

[GenralSpecific]

I suspect that the thicker red wire is switched 12v and runs all the way up to the front. I recently installed a radar detector and I trapped in to what I think is that same wire, just up at the front. I bet if you test it, you’ll see 12v show up when you open the car door, like when the radio is on.

 

[Quorky]

I suspect that the thicker red wire is switched 12v and runs all the way up to the front. I recently installed a radar detector and I trapped in to what I think is that same wire, just up at the front. I bet if you test it, you’ll see 12v show up when you open the car door, like when the radio is on.

The red reads 12ish constant, even with the car off..., the yellow reads same and black reads nothing with the car in park, in drive, left, right blinkers, nothing... i am running these test with a voltmeter and tail lights disconnected (not sure if that effects the resistance or output of the wire.

i expected to see red as constant and the other 2 as blinkers, varying voltage... whats puzzling me is that the setup (adapter wise) is similar to what you would find in a standard harness but i am not getting the expected readings via the volt-meter. I am also not 100% sure i am testing everything properly but figure if I am getting a reading off the constant, i should be getting a variable reading on the blinking wires...

 

[Puddles]

I found what seems to be a great tap on the “penthouse.” Remove the rear seat, take off the styrofoam protector from the RHS front corner, and voila. 12 v taps. And, it’s an easy run to the trunk from there.

there’s more to that story too though. Initially I ran wires from there directly to power my no-splice harness controller. It did work as a power supply, and in theory it should be EXACTLY THE SAME (electrically speaking) as wiring to the battery. I believe that wiring goes directly there. But then I tried to get fancy and put a terminal block in the trunk, for future accessories. I hooked that up and promptly blew a breaker. Red warning messages, no radio, and instructions to call service. Gulp.

fortunately that particular breaker is self resetting after the car sleeps, so I let it do that and all was well. But it did give me pause.

 

[Quorky]

alright, so as per some googling and researching, it seems that you have to activate the tow / trailer option so i figure the harness will only be usable as an active harness (via software) as opposed to always putting out the brake, left/right blinkers, passively.

I did use part of the harness. Used the red lead wire as the power source for the harness and tapped into the tail lights for the wiring. all in all, fairly easy, but quite a bit dirty and a little trouble getting into the tight places...

i went the stealth hitch route with the rack/tow combo package. so if anybody has any questions, let me know and i will be happy to answer them for you.

thanks to all that responded

 

[Quorky]

Some pics