Instructions for Tekonsha ZCI Wiring Kit Explained for a 2012 BMW 135i

Question:

Purchased a ZCI package for use on my BMW 135i vehicle. The instructions are so cryptic, I have no clue as to how to begin. How about sending me detailed instructions for my car so I do not have to spend 10 hours figuring out how these cryptic instructions apply to me. Your marketing indicated that this should have been easy. So far, it is anything but. Please, for you guys, hooking this up would be childs play. I am happy to invest time, but need some clue as to what to do. Thanks.

asked by: John C

Expert Reply:

I can help explain the instructions better for the ZCI Circuit Protected Vehicle Wiring Harness # 119250KIT, but I don't have the details about the wiring on your 2012 BMW 135i so you will need to do some testing with a circuit tester # PTW2992 on your end.

The first thing you need to do is determine what kind of lighting system you have by using the circuit tester to see what happens to the different wires when you use the brake pedal, turn signals, and use your headlights. You can use the "input sensor" list to help you identify which one you have. Once you find out which type of lighting system is on your BMW then you can determine if you need to connect all of the wires or leave off any wires by following the row of your wiring system to the "Input Wires Exceptions" column. Once you know this you can use the "Input Wires Used" to determine which circuits you need to clamp these wires to.

These are the 2 parts of the instructions that you need to pay attention to when determining where to connect what. The rest of the boxes are more about tips and recommendations on what to do when you go to actually connect everything up. Don't forget to also follow the module learn mode and verification after all is said and done.

I know these instructions basically look like Tekonsha threw up all over the page with information, but in their defense this is a truly universal wiring kit that can be installed on any vehicle so it does present a unique challenge in making sure all of the info is out there since there are so many different applications.

Hopefully the way I explained it will help clarify how to look at the instructions. I'm also attaching an installation video we shot on a 2013 BMW 3 Series that you can follow to get an idea. Keep in mind that since this is a different vehicle there might be some parts of the video that are different to your application.

expert reply by: Jon G