Trouble Finding the Stop Light Switch on a 2012 Mercedes-Benz ML350

Question:

Hello, I am currently installing this break controller on a 2012 Mercedes ml 350, and have had no problem with the install except for one little issue. when testing to find the break wire red by pumping i cant seem to find the connection. there are 4 wires coming out of the break, one being the power line that constantly stays on but the other wires on the plug dont seem to show any voltage when i use my tester. i have heard that leaving the vehicle running will turn it on but still no luck. i have even tried to close the door while testing, thinking the vehicle does not power the breaks while the door is open. Long story short, i need to find out on a 2012 ml 350 where to connect the red wire. would really be great if you could help me out, thank you!

asked by: Connor H

Helpful Expert Reply:

The first thing that comes to mind after reading your question is that on some of the Sprinter vans you actually need to use a circuit tester that has an LED light to find the stop light switch. For some reason on some of the vans that circuit has so little output that a tester with an incandescent bulb cannot detect the signal.

Try testing it with a tester that has an LED light and if that does not work then the next best thing would be to contact your local Mercedes-Benz dealer to see which wire you need so that you can install the Prodigy P2 # 90885 on your 2012 ML350.

expert reply by: Jon G