away2maine

Looking closely at picking up a 2009 or 2010 GL450. Driving 3/4 ton diesel truck now, so not interested in 350 (at least not right now). Is there anything beyond the hitch and brake controller necessary on these rides? Meaning is there any special tow package that needs to be in place before adding the hitch and controller? I'm spoiled with my current truck coming with everything I needed except the trailer.

wae

Wit the factory tow package, the system will recognize when the trailer is connected to the electrics and will change a few behaviors. I know that the blind spot system will be deactivated and the parking sensors in the rear will shut off. The airmatic system will not lower at highway speeds, and I thought that I read that it will change shift points in the transmission as well, but I'm not positive on that. Given the work involved, I'd look for an example that already has the tow package, rather than taking the back end of the wagon off to put a hitch on. Also, your brake controller connection is very specific to MB and I wasn't able to easily find an adapter. The PO of mine just cut the green connector off and I'm going to snag a Ford connector from the junkyard and patch it in so I have something more standardized and available.

I know that you've said you're not looking at the 350 because you're coming down from a 250 or 2500, but they don't rank the capabilities of the GLs in the same way. They all have a 7500 pound max and the diesel in the 350 has grunt for days with right about 400 ft lbs of torque.

away2maine

@wae

Thanks for the reply and the information. All good stuff to know.

On the topic of the 450 vs. 350 it is about gas verses diesel for me. I've been touring around in a Duramax diesel for the last 14 years and am somewhat in the mood to transition back to gas. I understand the benefit of the diesel and haven't completely closed my mind to it. Nothing more, nothing less.

I would love to find a GL with the hitch assembly and all already installed. I am looking to be in the $20k range which pulls down the inventory available. Most of the nice pieces with reasonable miles (under 90k) and reasonable price don't have hitch assembly installed. Most of the pieces that do have the hitch installed are well north of 100k miles. Any estimates on the all-in cost to install hitch assembly and appropriate trailer wiring?

Thanks...Peace...Away...

wae

I don't know if Curt or Draw-Tite make a bolt-on hitch, but I believe the MB one is around a grand or so. I believe they use a different wiring harness for tow package vs not, but I'm not sure. You could tap into the regular harness and add some relays if the provision for the factory harness isn't there and then run a separate wire up for the brake controller.

If you're taking it to your MB dealer and having them retrofit the tow package, I'd bet you're​ around 2k, but that's just a guess.

srfrboy

I have a question about the brake controller. I have a 2013 GL 550 with the factory MB tow package. It has the 7 pin wiring from the factory. Does that mean the car comes with an Electric brake controller?

Thanks fellas.

DennisG01

No, it does not. But you would easily know if you have it, or not. There's no way to hide it - you would see it in the cab.

I don't know the specific answer here in regards to MB, but just because there is a round 7-pin connector under the bumper, it doesn't mean that all of the pins are wired up. Maybe MB does, but many manufacturers do not.

wae

There isn't an integrated brake controller like a truck could be optioned with. If the factory tow package was installed, though, there will be a harness connector up in the driver footwell for you to add one. It's a green connector that should be tucked under the carpet or hanging by the OBD-II plug.

There's no good place to mount the controller though. You've got the knee airbags below the steering wheel and then a fairly busy dash.