I have searched and read all the posts pertaining to this, but still can not find the green plug that is suppose to be under the dash, taped to the diagnostic plug on my GL450 MFD of 01-07.
I even looked by the rear SAM and no green plug there either.

My 07 did not come from the factory with the hitch installed.
I purchased the hitch from the dealer and installed it my self.
The rear SAM that came with my 07 did in fact have the spot on the SAM for the hitch to plug into and just needed to be reprogrammed.
I need to find the factory green plug to install the tekonsha p3 trailer brake controller, or do I not have one because the GL did not come from the factory with a hitch?

Anyone know?...Thanks

 

Not sure but it should be there, check with the parts guy at your dealer to see if they can help. My 2010 did not come with a hitch but the green plug is there. If not get the wirless one from prodgy its nice they say.

 

I understand from reading earlier posts that some of the '07s didn't have all the towing stuff installed - including the necessary plug. Wireless will be MUCH easier than pulling wires to the rear.

 

Looks like I will be pulling wires.... Dealer is of NO help!!!

 

go wireless

 

I allready bought the p3... mail order, as well as the MB plug that will not get used.

 

Agreed. My Tekonsha Prodigy RF just showed up yesterday. What a dramatically better solution that is.

- Mark

 

OH ....that thing is so cool!!!!!!
I have got to call the co. and see if I can return the p3 for one of those.

 

Guys,
I've started digging around for the green trailer brake controller plug. My '07 GL450 was built in early '06 and came with the trailer hitch. I was not able to find the connector under the dash nor have I been able to find it near the rear fuse box. I did find the one shown below but this can't be it as it only has three wires. The service bulletin cleary shows a green plug and describes four wires. Do any of you guys have (or could take) photos of the fuse box area showing the connector?
Is there a chance it is not there? If it's not I will have to manually tap into the brake light switch and find a way to get the brake signal into the 7-way plug. Ground and power leads should be pretty easy. If i go this route do i need to pay attention to which SAM is in the truck?
The prodigy RF would be a good solution but I'd need to swap it every time I tow a different trailer.

 

Wow, they really did a great job of hiding the green plug. I found it aft of the sub box about half way down and wrapped in black tape. This truck has a production sticker of 03/06 so it seems even early production units had the green connector (at least those with factory installed hitches).



So next set of questions:
According to the manual there should be three fuses related to hitches and trailers. Those should be installed as follows:
Position 70 (20 amp) - Trailer Hitching
Position 71 (30 amp) - Trailer Brake
Position 72 (15 amp) - Trailer Hitching

On my vehicle, only fuses 70 and 71 are installed. I image that fuse 71 is there to feed the brake controller and 70 feeds power to the SAM for trailer lighting. Does anyone elses truck have fuse 72 installed? What is it for? Also where do I find the rear sam and what does it look like? Thanks for the help.

 

I don't have a fuse, or even a holder, at position 72. I have a 2010 ML BlueTec with factory hitch.

I also use the Prodigy RF brake controller and it works great. I talked with a Tekonsha Tech and he said the performance is identical to the P3.

The RF controller works well for one trailer pulled by more than one vehicle, because the inertial unit/controller is bolted to the trailer frame.
A hard wired controller would work better for one tow vehicle and multiple trailers.

I may be borrowing a trailer, so the Tech said if I temporarily bungee the RF controller to another trailer frame, make sure it is SOLID because any movement will cause erratic braking.