Troubleshooting Trailer Wiring Harness with Turn Signals Not Working On 2017 VW Tiguan

Published 05/22/2020

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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit

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LCD Digital Circuit Tester

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Question:

This is in regard to Troubleshooting Trailer Wiring Harness with Turn Signals Not Working On 2017 VW Tiguan Continuing from previous Expert Reply . . . As you can surmise, Im not the installer/electrician. His name is Ken, quite a nice and intelligent guy. Anyway, Ken very kindly let me record this video which explains in his view what is missing from the Tekonsha kit. My understanding is that the fault is NOT the circuit board he also checked for bent pins etc but rather there are two wires missing red and brown. Heres a short video where he explains it. Btw, you guys are an amazing ecommerce company focused on customer service. Its something I teach in my classes. Im a university professor in New Hampshire.

asked by: Howard F

Expert Reply:

To confirm it is a controller module (circuit board) issue with harness # 118675, I recommend double checking your connectors to make sure there isn't a bent pin and the connections are tight and then making sure the ground connection is bare metal where connected. Then using a circuit tester like # PTW2992 you can confirm power is getting into the black box from the connections but not exiting it correctly. If it is receiving but not sending correctly then it is a faulty module.

expert reply by: Jason S

click to enlarge

Howard

5/22/2020

Jason S.

5/22/2020

Thanks for the video and photo as I see what Ken is missing with the Tekonsha harness. His use of a standard harness as he called it that has a separate brake circuit is not how your vehicle is wired. You have what is called a multiplex circuit which has all the functions available on a the same wire on the left side and the same wire on the right side. The multiplex wiring sends all the stop/turn/running light functions down the same wire on both sides and then the module separates out the running light to a different output for the trailer as is required for the 4-way. I reached out to my tech contact at Tekonsha to confirm this. He said your vehicle is an odd one because some of the Tiguans even within the same year have slightly different wiring and that can cause issue. If you prefer to hardwire those functions like what Ken was talking about then you can alternatively use the # 119190KIT according to my tech contact because it works with multiplex systems.