# retrofit trailer hitch, what control module is the right one?



## blerg (Aug 16, 2017)

I want to add an aftermarket trailer hitch to an SE with tech.
Need to find the right control module.

VCDS on Atlas with trailer installed shows this in VCDS

Address 69: Trailer (J345) Labels: 5Q0-907-383.clb
Part No SW: 5Q0 907 383 L HW: 5Q0 907 383 L
Component: Anhaenger H27 0260 
Revision: 8C001004 Serial number: 0430201804
Coding: 0200000200000000
Shop #: WSC 09003 957 00200
ASAM Dataset: EV_TrailFunctGener2Hella 001008
ROD: EV_TrailFunctGener2Hella_VW27.rod
VCID: 40CC8168DBD1414724-8014

How can this information be mapped to the correct module to be purchased?
What other vehicles have this module ?


thanks


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## jyoung8607 (Feb 14, 2006)

blerg said:


> I want to add an aftermarket trailer hitch to an SE with tech. Need to find the right control module.


It's not entirely clear to me that retrofitting J345 is simple, whether the vehicle-side wiring of the J345 module will be present without factory towing. The SSP strongly implies at least some of the wiring is missing, specifically the bit that runs up front for an electric brake controller. But more information is always better, so I'll throw some things out there and you can make of it what you will.



blerg said:


> Serial number: 0430201804


I see you found my Auto-Scans.  Want to help the forum out and share your own? If posting your VIN bothers you, you can XXX out up to the last 6 digits.



blerg said:


> How can this information be mapped to the correct module to be purchased?


The hardware part number listed is the most relevant. That will get you the module itself. From there, I can see in VW's parts catalog that the J345-to-bumper wiring harness is conveniently orderable as a single part and at a less than horrifying price. On top of this, you'd have to figure out how to integrate J345 into your vehicle -- do NOT assume you can just plug it in. And there'd be some little sundries needed to do it up right assuming you want it fully OEM style. But those are the big ticket items. 

*J345 trailer recognition control module:* 5Q0 907 383 L, dealer list $299.00
*J345 to bumper wiring harness:* 3CN 971 124 A, dealer list price $73.33
*OE tow hitch, should you want it:* 3CN 803 881 B, dealer list price $370.00

I also see the different parts for the upgraded alternator and radiator fans, but I'm not sure if they're entirely plug and play, and I don't want to go too far down the rabbit hole tonight. Sometime in the next few days, if I get a chance, I'll see if I can locate J345 on my vehicle and take some pictures of what harnesses are going where. From there, maybe you can see what you have in that space. If you're lucky, maybe there's a vehicle-side connector sitting there just waiting for you.


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## blerg (Aug 16, 2017)

jyoung8607 said:


> *J345 trailer recognition control module:* 5Q0 907 383 L, dealer list $299.00


Thanks a lot!
My SE with Tech is 'trailer prepared', whatever that means, I will found it out.

The 5Q0 907 383 L seems to be specific for the Atlas,
The (5Q0 907 383 G) (last character G instead of L) seems to be more common in other vehicles (used controllers available).

Any chance that a 5Q0 907 383 G would do the job?


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## der_apoteker (Mar 27, 2017)

Do you have a build date for your SE? I am interested in doing this very thing... also can someone post the part numbers for the alternators? Might be handy reference 

Sent from my SM-G900R4 using Tapatalk


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## jyoung8607 (Feb 14, 2006)

blerg said:


> Thanks a lot!
> My SE with Tech is 'trailer prepared', whatever that means, I will found it out.


Hmm, I have seen a lot of references to 'trailer prep' in the PR code list and wiring diagrams, as distinct from actually having the trailer hitch. This may be cause for hope. From browsing around the Interwebs a bit this evening, it seems like the Tiguan has a sort of similar arrangement.



> Any chance that a 5Q0 907 383 G would do the job?


Partslink24 sucks at showing me part supersessions and crossrefs. I usually use Jim Ellis VW Parts for that, but they don't have MY 2018s loaded up yet. So I dunno for sure. I can tell you I'd be leery of it.

J345 trailer detection touches a LOT of things in the vehicle. Upon J345 detection of a trailer, off the top of my head, it disables Eco shifting (minimum becomes Normal), it knocks out blind spot assist and rear cross traffic alerting since the sensors are blocked (this one is super annoying because they do NOT automatically come back on when you disconnect the trailer). It fiddles with start/stop behavior, fiddles with rear PDC behavior, adds some alarm functionality (looks for the trailer becoming disconnected while locked as a criteria for setting off the alarm), and prevents the power tailgate from fully opening when triggered from inside the cabin and possibly the remote (haven't tried the remote). This is just stuff I know off the top of my head. It may feed back into ABS and stability control behavior too.

That's not to say all those smarts are in J345, it may just be shouting on the CAN bus "hey we got a trailer all up in here" and depending on the other modules to react. It might work, particularly if it was taken from another MQB platform vehicle and the wiring happens to match, no idea. It might or might not fly. Or, it might partially fly in a way that could be hard, and potentially unsafe, to predict. If it were my Atlas, I'd do it up OEM-spec with the right module. Actually if it were my Atlas I were planning to tow with, I'd order it with the factory towing package. But that's just me.


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## jyoung8607 (Feb 14, 2006)

der_apoteker said:


> Do you have a build date for your SE? I am interested in doing this very thing... also can someone post the part numbers for the alternators? Might be handy reference


Sigh, fine.  Down the rabbit hole we go.

Four alternator variants. Each pair has a new and a rebuilt (trailing X) part listed. PR-8GU/9G2/9G3 refer to the alternator capacity. PR-TV0 is definitely the 3.6L VR6, I believe PR-TI6 is the 2.0L TFSI. The prices are interesting: the 180A towing package alternator is the cheapest by far at $415 compared to $800-$1200 for the other three variants.










The cooling fan situation is simple in some ways: they're all $275 and they all appear to fit in the same fan carrier shroud. You get two 400W fans with the towing package (PR-1D6 towing hitch) and a 300W/400W set without (PR-1M5 trailer prep, PR-1D0 no trailer hitch). I have no idea why there are separate part numbers for a 400W towing and 400W non-towing fan on that one side. I have not researched to see if these are plug-and-play in terms of wiring. Furthermore, non-towing vehicles will have those air shutters that close for fuel economy when not needed for cooling (not shown here) and I don't know if/how the ECU would react to those being removed for a proper OEM towing setup. Coding or firmware changes may be involved.


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## der_apoteker (Mar 27, 2017)

Thanks for the info. This is really helpful! While installing this, I wonder if possible to add the 
J938 Rear Lid Opener Control Module (Virtual Pedal) and sensor


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