Does 2003 Mercedes ML320 Need Brake Controller to Activate Trailer Brakes

Updated 07/28/2020 | Published 07/24/2020

Products Featured in This Question

Curt 4-Way Flat Trailer Connector with Circuit Protected Powered Tail Light Converter

(65)

$39.10

Curt Echo Wireless Brake Controller - 7-Way Plug-in w/ Bluetooth App - Up to 2 Axles - Proportional

(1802)

$289.95

Question:

Hi I have a 2003 Mercedes ML 320 with a 7 pin wiring connector. When I connected it to my trailer and I apply the brakes, the trailer brakes will lock skidding the tires. I noticed that the car doesnt have a brake controller. If needs one could you please send the info to get the correct one. Also, I have a utility trailer with a 4 pin connector, do you have an adapter for it? thanks a lot

asked by: Mario

Helpful Expert Reply:

Sounds like the brake lights circuit of your trailer wiring was either accidentally or intentionally ran to the brake output circuit of your trailer wiring which is why your brakes lock up when the brakes are touched. You do need a brake controller to take care of applying the brakes as full 12 volts from a light circuit will always lock them up. A brake controller will vary the voltage of the circuit to give the brakes the correct amount of pressure.

The easiest solution is the Curt Echo part # C51180 which basically just plugs into an active 7-way and once synced to a smartphone is ready to tow with.

For a 7-way to 4-way adapter you could use just the part # 707250 as well.

expert reply by: Jameson C