Hi All,

Having just bought our second hand GLC300 2020, I am having trouble figuring out what towbar option to go with.

I've had a lot of bad experiences with "cowboy" fitters in the past, so I actively avoid taking my vehicle to somewhere where they will rip off bars, panels or anything else, break clips and tabs, and ruin my new baby. ;-)

I checked the VIN of my Merc, and can see it has this option from factory:

554 "Pre-installation for trailer coupling" - I am wondering what this means exactly.

I am aware that several safety features need to be disabled when a trailer is connected and detected, so this is not as simple as other cars, but the risks associated in going aftermarket seem to stack up after you have called around a few places and realize how inexperienced they sound - none of them sound like they know what they are doing, and they could brick your vehicle in the process of installation and "coding".

My questions is: Does anyone know what the above code actually means from factory? Would I expect to find a short wiring loom zip tied behind the bar with the necessary power wires for the indicators, brake, tail light and service brake etc ready to connect to a 7/12 pin flat plug?

Does the code simply mean that I need to purchase a particular loom or additional ECU from Mercedes and plug it in, and the vehicle will recognise the module, and coding is not required?

I would like a Hayman Reese bar given the load rating sounds larger for their 03378RW part (I think it might be 2200/200kg rated - even tho the vehicle itself is limited to 2000kg), and I spoke with Mercedes Parts today and they stated their factory option was 2000gk/96kg tongue weight - which sounds excessively low - my 1400kg trailer would immediately exceed this tongue weight at around 110/120kg!

Looking at historical posts on here, it sounds like this was last visited in 2016, and Hayman Reece did not have an option at the time - the model is also 2020, so this information is not likely relevant.

Any info appreciated!

 

I'm just guessing it's a prewired harness. Take a look under the rear of the vehicle.

I have the code 550 which is the factory hitch option for $575 on my 2022 GLC. USA

 

Thanks for the reply!

I don't see anything obvious in the bumper area (definitely no socket fitted), but I would have to remove the bar and paneling to see if they have wired something into the rear SAM.

I can't see any additional fuses occupying the respective slots that get used up when fitting the Westfalia kit (fridge and "always on" power) - which I have read here and elsewhere is the brand that is apparently the OEM choice by MB.

I am wondering if MB will try and hit me up to have the whole kit supplied, fitted and coded by them, or if they will just code it if I fit myself - lots of dealers love to extort money from people under the guise of safety - having been burnt by cowboys in the past.

Does anyone know what Westfalia part number is sourced by MB as part of the stock kit option?

I found this on a towbar site in AU (no link, as it would probably go against forum guidelines). The instructions go into excellent detail on installation, and taking it to a dealer or indy to be coded:

 

2016 and cost was $3000 for bar, wiring kit and around 6 hours labour. Our click to open still works, never disabled. I posted back then the install paperwork MB uses. Time might have been a bit long, but we probably were helping them train staff. That said, the documentation did state how much time should be allocated. Westfaila was only option back then. One issue, depending on ball weight, rear steel springs and shocks can suffer from bump stops engaging body when travelling over uneven or rolling road systems. I always insist on all documents and sometimes packaging when work done, incl old pads, discs and air filters in boot after service. Several times we suddenly did not have to replace discs !!