2013 GL450 Tow Harness
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Junior Member
Joined: Mar 2007
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From: SoCal
06' BMW 550i
2013 GL450 Tow Harness
Under my 2013 GL450 there is a MBUSA factory tow hitch receiver, but I could not find the wiring harness for trailer brake lights. Is the wiring harness not included from the factory?
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A gaggle of MB's
If the factory hitch was installed at the factory - the spec sheet will show that - yes, included the wiring.
If the hitch was installed at the dealer - and the owner did not want/need wiring - then yes, the dealer could have installed the hitch w/o wiring harness.
If you just need "standard" wiring - then any U-Haul can add wiring connection for you - using Modulite module.
Keep the beat !
If the hitch was installed at the dealer - and the owner did not want/need wiring - then yes, the dealer could have installed the hitch w/o wiring harness.
If you just need "standard" wiring - then any U-Haul can add wiring connection for you - using Modulite module.
Keep the beat !
Thread Starter
Junior Member
Joined: Mar 2007
Posts: 26
Likes: 0
From: SoCal
06' BMW 550i
On my the original window sticker it shows:
"Electronic Stability Program (ESP) with ESP Trailer Stabilization"
Underneath, there is a hitch but no connectors. I'm a bit confused because anytime I've owned a factory installed hitch, there already a connector installed.
For the 2013 GL450, what's the part # for the harness and do I need the dealer to program anything? I do not want to do any u-haul options.
"Electronic Stability Program (ESP) with ESP Trailer Stabilization"
Underneath, there is a hitch but no connectors. I'm a bit confused because anytime I've owned a factory installed hitch, there already a connector installed.
For the 2013 GL450, what's the part # for the harness and do I need the dealer to program anything? I do not want to do any u-haul options.
Super Member
Joined: Apr 2016
Posts: 889
Likes: 148
From: Southern Illinois
, 2023 BMW X4, 1991 190E
Looking at your hitch, the hole to the left of the receiver is where Mercedes normally has the electrical contacts for the hitch. Either it has fallen out, or like said in an earlier post, the owner just had the hitch installed without the electrical connection. I have done this on several of my cars, since I only use it for a bicycle rack or during daylight towing of my utility trailer.
If possible I would get someone to run your VIN number and it would have if it had the trailer option from the factory.
You have a couple of choices if you need to get the electrical installed, either buy; a electrical kit from the dealer ( which I did one time) and had the dealer install it or go to a store that does recreational vechiles and have them install an after market one. I did that on my last two cars.
If possible I would get someone to run your VIN number and it would have if it had the trailer option from the factory.
You have a couple of choices if you need to get the electrical installed, either buy; a electrical kit from the dealer ( which I did one time) and had the dealer install it or go to a store that does recreational vechiles and have them install an after market one. I did that on my last two cars.
Thread Starter
Junior Member
Joined: Mar 2007
Posts: 26
Likes: 0
From: SoCal
06' BMW 550i
Looking at your hitch, the hole to the left of the receiver is where Mercedes normally has the electrical contacts for the hitch. Either it has fallen out, or like said in an earlier post, the owner just had the hitch installed without the electrical connection. I have done this on several of my cars, since I only use it for a bicycle rack or during daylight towing of my utility trailer.
If possible I would get someone to run your VIN number and it would have if it had the trailer option from the factory.
You have a couple of choices if you need to get the electrical installed, either buy; a electrical kit from the dealer ( which I did one time) and had the dealer install it or go to a store that does recreational vechiles and have them install an after market one. I did that on my last two cars.
If possible I would get someone to run your VIN number and it would have if it had the trailer option from the factory.
You have a couple of choices if you need to get the electrical installed, either buy; a electrical kit from the dealer ( which I did one time) and had the dealer install it or go to a store that does recreational vechiles and have them install an after market one. I did that on my last two cars.
Do all the GL450 with the factory installed hitch option come standard with electrical connections (where the left hole is)?
I guess I have to make an appointment with MB to get the bottom of this.
Thread Starter
Junior Member
Joined: Mar 2007
Posts: 26
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From: SoCal
06' BMW 550i
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MBWorld Fanatic!
Joined: Nov 2012
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A gaggle of MB's
Let me try to clarify for you:
1. If the hitch was installed at the factory - it would be listed as "Trailer Hitch" under options - and would include the factory wiring harness including connectors at the back
2. Yes - in your rig the ESP does have Trailer Stabilization - IF the trailer hitch was factory installed OR if MB hotch was dealer installed including wiring harness (big job)
In your case - from what you say - and from what the owner you bought it from - YES it sounds like you have a MB dealer installed but without the additional expense of installing the factory wiring harness.
Frankly - if you just need basic trailer wiring - any U-Haul store can clip that it - with Modulite relay - etc..
1. If the hitch was installed at the factory - it would be listed as "Trailer Hitch" under options - and would include the factory wiring harness including connectors at the back
2. Yes - in your rig the ESP does have Trailer Stabilization - IF the trailer hitch was factory installed OR if MB hotch was dealer installed including wiring harness (big job)
In your case - from what you say - and from what the owner you bought it from - YES it sounds like you have a MB dealer installed but without the additional expense of installing the factory wiring harness.
Frankly - if you just need basic trailer wiring - any U-Haul store can clip that it - with Modulite relay - etc..
Super Member
Joined: Dec 2004
Posts: 921
Likes: 36
From: CA
MB
Most people think that trailer hitch with a tow ball to haul is enough, well if you are planning to move a small 7x8 trailer with a sod cutter is not a problem otherwise hook a trailer, travel trailer or a boat to your GL connector is very important not only for the trailer lights, it is important because the GL will adjust the brakes it self, will adjust the airmatic / air bags, will adjust the lane keep assist option, basically the GL will recognize that is a trailer behind and will adjust settings for your safety, sometimes people try to save a few $ but in exchange will have a $1000 + air matic shock damage. Get a Wiring harness is a smart decision. 
