Cable routing for OEM Towbar, Trailer Assist, Side Assist, TPMS and an extra 2 rear parking sensors - Help Required

[DubHaus]

Hi All,

OK, so I'm currently planning a few upgrades, namely, an OEM Tow Bar and Loom, Trailer Assist, Side Assist, TPMS and the extra 2 sensors on the rear bumper for PLA. and.... I have a few questions.

As I'm almost at the stage to insulate, sound deaden the cab, fit the Alpine Sub under the drivers seat etc. I thought it would make sense to run all of the necessary looms in one go.

Question One, is there a diagram showing the cable routing for the above looms? I've seen Paulys post >> Here << for the Tow Bar Loom but can't locate one for the Side Assist, extra sensors for PLA and TPMS

Question Two, I'm slightly confused by the Trailer Prep or not scenario! I don't have any modules under the drivers seat apart from the one installed for the OEM LED Headlights. If I order 7LA055204 does this come with the necessary module and all cabling for a 13 pin socket?

Question 3, PLA (Self Park?) I've got the highline rear camera and 4 rear sensors. How and where do the additional sensors connect? Aside from fitting the additional 2 sensors on the side of the bumper(s) front and rear is there anything else I need?

Question 4, Once PLA is complete, and the towbar is wired in does that then enable Trailer Assist?

Any and all help, advice etc. greatly appreciated

 

[roadtripper]

Can't help with runs but I had the modules out from the driver's seat this weekend to hunt a rattle, the large module that's out is the trailer module that is normally clipped to the same mount as the light module on the left od the seat base looking forward.

What do you have under the passenger seat? The trailer feeds come from these fuses.

 

[DubHaus]

@roadtripper The only things under my passenger seat are the fusebox which is 90% un populated and one relay and about 6 connector blocks

 

[roadtripper]

So on mine there is this strip at the front of the passenger seat base fuse box, the 30amp are the tow bar module feeds



And you can unclip this sub fusebox and see the large feeds going to it



You might find if you look at the looms there that you might find those feeds in place, I think some folks have found them folded back and taped to the loom.

 

[DubHaus]

@roadtripper mines similar


The four fuses on the left are my additions for the eberspacher etc.


and ignoring the extra red feed cables, mine hasn’t the additional fuses (5&30A) as yours, however as I’ve 7 spare ways on the permanent live I should be ok for the towbar. It’s the supplies for all the other extras I’m not sure of

 

[DubHaus]

Can anyone help with the cable routing for side assist, extra 4 parking sensors and TPMS?

 

[Two7Five]

Bear in mind if you’re fitting the alpine sub, it’s super tight under the drivers seat afterwards. I’ve a (Motexion) bulkhead in, and didn’t mind having the amp on the rear of the sub, but it would be impossible to adjust or tinker with it once the seat and bulkhead are in, plus I had to stick the single module I had under there originally to the side of the seat base, removing all the clips and brackets. You’ll unlikely get anything else on the drivers side. (Trailer prep is there originally I believe, I had no tow bar prep. Located mine under the passenger side near to the power feed.

There’s a decent chunk of cabling under my drivers seat which I tidied up and relocated whilst the flooring and seats were out. Essentially, don’t bank on putting the trailer or additional modules under the drivers side and whislt in there make sure you have a tidy around, the ‘tunnel’ between the seats will take a lot of reorganised factory cable and loops, plus the overage from the towbar can bus cables (which where a b4stard to get done / re pin btw)

Personally I’d not want the lane assist on a transporter, does it work when towing?

Plenty of occasions of the Sprinter I’d like to turn it off, but OK as a second check when overseas.

 

[DubHaus]

Bear in mind if you’re fitting the alpine sub, it’s super tight under the drivers seat afterwards. I’ve a (Motexion) bulkhead in, and didn’t mind having the amp on the rear of the sub, but it would be impossible to adjust or tinker with it once the seat and bulkhead are in, plus I had to stick the single module I had under there originally to the side of the seat base, removing all the clips and brackets. You’ll unlikely get anything else on the drivers side. (Trailer prep is there originally I believe, I had no tow bar prep. Located mine under the passenger side near to the power feed.

There’s a decent chunk of cabling under my drivers seat which I tidied up and relocated whilst the flooring and seats were out. Essentially, don’t bank on putting the trailer or additional modules under the drivers side and whislt in there make sure you have a tidy around, the ‘tunnel’ between the seats will take a lot of reorganised factory cable and loops, plus the overage from the towbar can bus cables (which where a b4stard to get done / re pin btw)

Personally I’d not want the lane assist on a transporter, does it work when towing?

Plenty of occasions of the Sprinter I’d like to turn it off, but OK as a second check when overseas.

@Two7Five many thanks I think I’ve pretty much worked it all out! But thanks for the info. I think be managed to fit the trailer and LED headlight module (separately) directly to the seat base on the handbrake side with the alpine amp on the door side of the seat base. Had a word with my bro in law who’s a master tech at Wolsey VW Dealership and he said the trailer looms used to be fed via the factory route, I.e. up the D Pillar, along the roof and down the passenger B Pillar but to reduce install time they’ve now wrapped them in spiral conduit and route them underneath! But that does leave about 1.5-2 metres of extra cabling floating around! Apparently they coil it up and secure it under the plastics underneath just behind the drivers seat!

The rest of the wiring I’ve run following logic and wiring diagrams etc. I.e. if it terminates on diagram under passenger seat I’ve taken it in D Pillar and along roof and down B Post. All seems neat enough now

I’ll post up some more photos in my build thread

 

[Two7Five]

Good stuff.

I wondered that on the OEM towbar loom. The one I have is long enough to go up into the roof, and I may well do that to be fair, as there isn’t really anywhere to secure it properly underneath.

Only issue may be that there is a lot of cabling up there already - mines a 4Motion with an auto latch rear and originally (not now) had rear wash wipe etc. It’s a lot of cabling and there isn’t a lot more room before it starts pushing the roof lining panels out. The junction box already used to rattle on the panel.

 

[DubHaus]

Good stuff.

I wondered that on the OEM towbar loom. The one I have is long enough to go up into the roof, and I may well do that to be fair, as there isn’t really anywhere to secure it properly underneath.

Only issue may be that there is a lot of cabling up there already - mines a 4Motion with an auto latch rear and originally (not now) had rear wash wipe etc. It’s a lot of cabling and there isn’t a lot more room before it starts pushing the roof lining panels out. The junction box already used to rattle on the panel.

If you take it up the N/S D Pillar then you can terminate the 3 earth wires on the Earth point there, saves a bit of space when you get to the roof