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Brake Controller Recommendation for for 2005 Mercedes ML500 for Trailer with Electric Brakes


Hi folks, I need electric brake controller for 2005 Mercedes ML500. It does not have the factory towing package. I successfully wired in a Curt 4-pole kit that I ordered from you last year. I now need a larger trailer and all of them have electric brakes. I cant find a brake controller thatll work for this very capable vehicle. Even my 1960s era camper has electric brakes and I cant use them! I cant be the first and only person who wants to tow with this vehicle. Whats the solution and what do I need to order to safely do this installation? Thanks,


Expert Reply:

Good news! I spoke to my contact at Horizon Global, who makes many of the brake controller brands like Tekonsha or Draw-Tite, and you should be able to use their brake controllers since they operate on the PWM signal (pulse width modulation) instead of on the output voltage signal.

The challenge for you will be to find the correct stoplight wire behind the brake pedal. He instead suggested you locate the CHMSL (Center Height Mounted Stop Light) wire to splice into on your 2005 Mercedes ML500. Since you don't have the tow package you want to look for the CHMSL wiring in the vehicle towards the third brake light. You may have to push back the wire loom to see the wire but according to your owners manual this wire may be orange, and is used for the 3rd brake light for your vehicle. To be sure this circuit you are looking for is one that will be active when only the brake pedal is pressed. You can do that with a circuit tester like # PTW2993.

Once you've found the wire you will want to splice into that wire with quick connects # SWC502905-1 and a 14 gauge wire # DW07550-1. This wire will need to be run back to the red wire on the brake controller.

The # ETBC7 is a great wiring harness to convert your 4 pole to a 7 way for your electric braked trailers.

As far as Brake Controller recommendations I really like the Prodigy P3 # 90195. This brake controller is a proportional controller, which means when you press the tow vehicles brakes it will send the amount of power to the trailer brakes to match the braking force of the vehicle. It also has a customizable full display screen which provides you with a full error messages instead of codes that need to be deciphered. This controller will work great for your vehicle.

expert reply by:
Jackie C

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