Help With Setting Up Curt Echo Trailer Brake Connector On a 2021 Mercedes GLE350 AWD

Updated 05/30/2024 | Published 05/24/2024

Question:

I recently purchased the Curt Echo Wireless Brake Controller. I have a 2021 Mercedes GLE350 AWD with a factory installed towing package that has a 7 pin connector. When I plugged the controller in and started the vehicle the controller light did not come on. The vehicle Bluetooth was activated. The vehicle owners manual is no help. I’m not sure if a trailer has to be connected for everything to work. I have a trailer on order and I’m trying to make sure things will work when I pick up the trailer. Can you offer any help on my particular vehicle. I expect to pick up a 7 pin tester tomorrow to help troubleshoot this problem. I’m attaching a photo of the wiring harness pins.

asked by: Don S

Trailer Wiring Connector On 2021 Mercedes GLE350 AWD
(click to enlarge)

Expert Reply:

Your 2021 Mercedes GLE 350 is most likely like a lot of newer vehicles where it will not send power to the charge line until it sees a trailer is connected and drawing power on the running light/tail light circuits. Once you have your trailer you will connect it to the Curt Echo # C51180 and should see the LED light flash green showing a trailer connected but not paired. At this point you will be able to pair it with the OneControl app. If you are still having issues with the LED lights you will want to check the trailer fuses and relays to verify they are not damaged.

expert reply by: Bud M

Don S.

5/29/2024

Thank you. I thought that may be a possibility so I took my vehicle to U-Haul and had them check the connection. Still no power. I’m at the car dealer this morning to have them sort it out. Veh is still under warranty.

Don

5/29/2024

FYI The dealer checked my 7 pin connection and found no problem and to be working as it should. I was told that they have purchased several aftermarket pin testers for their shop but found none to work on their vehicles but couldn't explain why. The opined that Uhaul was probably using an aftermarket pin tester. When I returned home I connected my vehicle to a friends horse trailer and everything worked fine, even the Curt Wireless Brake control had power when connected to the trailer. I assume a pin tester substitutes for a trailer connections and why one will not work on a Mercedes but will on other vehicles is beyond my understanding.

Bud M.

5/30/2024

@Don That does sound very strange. I hate it that vehicle manufacturers keep making changes to simple systems that are supposed to make things easier but only seem to add to the confusion.