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So, 2014 ML350 BlueTech with factory tow package. Found the harness right where it should be BUT there is 0 power going to it. I've ran the multimeter from ground across all 3 other wires to include the Red/blue that should be the BrakeController's power wire, yet 0VDC. Any ideas?
(Vehicle was on, pressed the brake a few times, verified the multimeter against the battery under the hood)
What wires are you testing? The ones in the front footwell, or the ones at the 7-pin connector under the bumper?
Is the 30A fuse inserted? Do you have power at the fuse block?
Which fuse block it would be on? Got a call back from the dealer and he said they might have installed the wrong rear SAM unit for my car even though I have the factory tow and harness installed. He gave me a part number to check but I have no idea where it's at nor what it looks like. I think that's some BS if it's the case.
Looks like a bit of an old thread, but I am in the middle of installing a brake controller in my 2010 ml, For some reason there is always a constant 3.5v on the small wire (black/red brake light cuircut wire) and only goes to 0 voltage after the vehicle has been turned off for a few minutes. Turning back on as soon as the brake is pressed, or the vehicle is turned on. There is no change in voltage when the brake peddle is pressed....
Anyone else ran into this issue? My Curt spectrum brake controller always thinks the brakes are being pressed....
@clowrym that doesn't sound right. That signal should only be present when the brake light is active. I am not familiar with your Curt controller, but Tekonsha controllers need to see that signal in order to provide a brake signal (big blue wire).
In other words, just decelerating or downshifting will not activate the controller because there is no brake light signal, and it will not send its variable signal to the trailer brakes.
See the attachment - did you fabricate a connector like shown there? Is that the wire you are testing? Or are you back at the 7 pin connector?
@clowrym that doesn't sound right. That signal should only be present when the brake light is active. I am not familiar with your Curt controller, but Tekonsha controllers need to see that signal in order to provide a brake signal (big blue wire).
In other words, just decelerating or downshifting will not activate the controller because there is no brake light signal, and it will not send its variable signal to the trailer brakes.
See the attachment - did you fabricate a connector like shown there? Is that the wire you are testing? Or are you back at the 7 pin connector?
Mine is a W164, but essentially the instructions are the same, I fabricated the Wiring based on the attached instructions, I have tested both the black/red wire per the attached & also checked at the 7 pin connector, Also gone through and tested all the wiring to ensure that it matched the mercedes instructions.....As well checked the rear fuse panel for proper placement of Fuse 71 & 72.
I just dont know what else i can check, From what I have read there is no brake light switch in the w164, so I cant tap into that........
After hours or trying different combinations and terms googling, I finally found someone with the identical issue HERE , I guess I will have to check with the dealer and make sure the Rear SAM is coded correctly!!
Mine is a W164, but essentially the instructions are the same, I fabricated the Wiring based on the attached instructions, I have tested both the black/red wire per the attached & also checked at the 7 pin connector, Also gone through and tested all the wiring to ensure that it matched the mercedes instructions.....As well checked the rear fuse panel for proper placement of Fuse 71 & 72.
I just dont know what else i can check, From what I have read there is no brake light switch in the w164, so I cant tap into that........
For what it's worth, I used those instructions on our W164, 2010 ML Diesel, factory hitch. The rear SAM was already installed and ready when we got it (new), so the instructions for the W166 worked fine.
Something else seems wrong.
I'd call Curt Engineering and ask them for feedback, maybe before talking to your Dealer. (Our local Dealer was absolutely clueless about the hitch setup - had to find one that was knowledgeable.)
Although the wiring harness worked fine with a Tekonsha P3, we ended up with a Tekonsha RF, which I think does a better job of controlling the trailer.
Also, Curt makes another bluetooth controller that some on our Lance Trailer forum (with W166's) have found to work. I'm not comfortable with an app to control the controller, but it seems like Curt is trying some new things.
The dealer said it could be a coding issue ont he rear sam, or potentially there may be some issue with it. Going to have them try and code it tomorrow am, and see how it goes
Well, Updated firmware & recoded the rear SAM, Now I have 12v when the Brake pedal is pressed & the trailer is connected....But the new issue is that the Voltage never drops to 0, even when the trailer plug is connected, 3.9v min... I have only tested with the trailer connected, not fully hooked up and driving, but I am reluctant to as the brake controller give me a solid red LED which indicates:
vLED display is lit red for more than 10 seconds: Red wire connected to ground side of stoplight switch or is shorted to ground
I would assume that if the brake controller is reading a fault, it wouldnt be outputting any power to the brakes, but I dont want to take that chance!!
Sent an email to the dealer again and will Call Curt tomorrow and see what they have to say about my issue! I have found another POST where everything worked once tested under load...I would assume under load would mean hooked up to the trailer, not necessarily driving....I jsut cant see there being a difference wether your driving down the road or Just connected
Adding OEM hitch equipment to my 2012 ML350 Bluetec
I am in the process of adding the OEM hitch part to my 2012 ML350. I have the hitch and wire harness mounted and am waiting for the SAM module to arrive. I was at our local Mercedes facility yesterday trying to get of the parts that were in the complete kit. I did find out that there were several complete kits ( 166-310-01-95 ) available from an out of state dealership even though it is listed as unavailable. I did have to make brackets to support the muffler heat shield and the DEF tank. Part numbers that I have purchased thus far are listed below. Not sure if there is anything else I will need. I guess I will need to take the car to have the software updated to communicate with the new module.
I will need information on were the SAM module is actually mounted, can anyone help with a photo of mounting and location, I do know it is somewhere close to the spare tire storage location?
OEM Hitch : 166-310-11-37
Wire Harness: 166-440-70-13
SAM Mod : 246-900-55-01
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