Troubleshooting Lights and Turn Signals Not Working on the ZCI Kit 119250KIT

Updated 04/09/2025 | Published 04/08/2025

Question:

2012 ML350 diesel. I am stumped trying to install the Tekonsha wiring for the 4-flat. Using the circuit tester, I located which vehicle wire is for lights, signals, etc. I attached the Tekonsha unit and trained it several times with the loads on the proper sides of the connectors. Even with nothing activated, I get constant power to the first two legs. Turing on lights or signals, nothing changes. Not sure what to do next.

asked by: Brian

Expert Reply:

Hey Brian! I would check the ground on the item # 119250KIT. Make sure there is a good, clean connection to a bare piece of metal. It's possible you have a bad ground and the brighter circuits of the stop/turn circuits can't pull enough amperage to power.

expert reply by: Jerred H