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Tekonsha 118831 trailer harness: brakes do not work

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I have just installed the eco hitch and tekonsha trailer harness (supposedly for Model Y 2021). After connecting the tester for the harness, I am getting turn signals working ok but brakes do not work. There were some reports of this on YouTube (in comments) but so far I have not seen any suggestions. Does anyone know how to fix this? I can get a different harness but would prefer to make this one work since the bumper and interior panels are off for the install.

Thanks!
 
Do you have the brake controller connected? this is an add on device that typically allows you to control the braking force (trailer loaded or unloaded). There’s a cable that you’ll need to interface the brake controller to the car. It’s located footwell area on the left. It’s a cable that you can get from Tesla.
ASY,HARN,TRAILER 1.00 $4.40 BRAKE ECU
ADAPTER(1072586-00-A.
Hope this helps.
 
Do you have the brake controller connected? this is an add on device that typically allows you to control the braking force (trailer loaded or unloaded). There’s a cable that you’ll need to interface the brake controller to the car. It’s located footwell area on the left. It’s a cable that you can get from Tesla.
ASY,HARN,TRAILER 1.00 $4.40 BRAKE ECU
ADAPTER(1072586-00-A.
Hope this helps.
No, I do not have brake controller connected.

Forgot to mention, model Y is 2021 (assembled in October, 2020).
 
Ok, I guess I figured it out. This harness does not work on the newer 2021 model Y. Tesla updated tail lights somewhere around middle of 2020 and this Tekosha harness is not connected to grey wire that is the brake wire in the new harness.

I will need either another harness or DIY into the factory connector.
 
Ok, I guess I figured it out. This harness does not work on the newer 2021 model Y. Tesla updated tail lights somewhere around middle of 2020 and this Tekosha harness is not connected to grey wire that is the brake wire in the new harness.

I will need either another harness or DIY into the factory connector.
Hi Dima . How did you fix the problem? I am in the same situation.
 
By the way, the guy in the video said that he had to leave the 4-pin wire (the one that connects to the trailer in his trunk storage compartment). There is a way (not easy but possible) to fish the wire inside the bumper and to the hitch plastic cover without removing the bumper.
 
By the way, the guy in the video said that he had to leave the 4-pin wire (the one that connects to the trailer in his trunk storage compartment). There is a way (not easy but possible) to fish the wire inside the bumper and to the hitch plastic cover without removing the bumper.
I still waiting for the new harness from Tekonsha. And they asked me to return back the old one.