Dangerous Battery and trailer harness wiring ?

[Destroyer-Dan]

Hi I’m new to owning a bmw 320d the other day I was looking in the boot for my wheel locking nut after a week of owning the car I remove the cover for the battery (unaware what it was at the time) to discover a mess of wires and I need help I believe the previous owner has tried to install a trailer wiring harness and failed horribly now I have to fix this dangerous mess can anyone locate me in the correct direction please as to what might be for what I know it’s a long shot but I’m hoping there’s a knowledgeable person that see this and can point me in the right direction thanks 

[Greydog]

Morning Daniel

Welcome to the Forum

That doesn't look good I always thought that the correct kit was plug and play??

I would contact someone like PF Jones who are specialists in Tow Bar fittings and wiring I know guys with X5's have found them extremely helpful.

Good Luck

Dave

[Destroyer-Dan]

Thank you for the fast reply greydog I went out this morning and removed the mess it looks like at some point the original wiring for the trailer electrics have failed and the previous owner has failed at installing a kit I’ve removed all the bodged electrics and used electrical tape on any exposed wires So it’s all completely safe and somewhat original now it also looks as if the rear parking sensors have failed as there’s a few more wires coming from the rear bumper up into the area where the battery tray is I’ve just taped up the wires just so they don’t get damaged and placed them to one side but does anyone know if I need to keep the wiring box that’s in the picture below please

 

 

 

[Greydog]

Hi Daniel

Smart move removing all the dodgy stuff, normally when a towbar is fitted the rear parking sensors are disabled when the trailer electrics are plugged in. The parking sensor control unit  has 3 plug positions on the top 1. rear sensors 2. front sensors 3. Bypass for tow pack.. Not sure how much you are into BMW's but here are a couple of websites that may help.

1) www.realoem.com This is a BMW Online Parts List  put the last 7 digits of your Vin into the search box it will bring up your Model so if you need spares you know it's right for your car..It also has small exploded drawings that help with where stuff fits.

2) www.newtis.info This is a Technical Information site that the DEalers use for replacement/repair information.

Good Luck

Dave

[Destroyer-Dan]

Thank you so much mate you’ve helped loads I don’t know anything about bmw so the links and everything your telling me is extremely helpful so thank you mate

[Destroyer-Dan]

Would you know if these two cables are for the original electric plug next to the tow bar 

[Destroyer-Dan]

Also I have these two cables left over one that runs along the main electrics and another that just comes from under the boot that trails into the battery tray area 

[Greydog]

Morning Daniel

Holy moly what a muddle 

BMW use Brown as a Common Earth/Ground wire but what the others are I am guessing like you. Is the radio OEM or after market? They could be a reverse camera perhaps? Or rear entertainment for children?

Get the old tester out for the Tow plug harness my X5 came with the OEM removable Towbar and single electrics, may be the clever clogs had wired his own twin electric system, if it helps the OEM cable is Black.

Take a look at www.newtis.info there are wiring diagrams which may give clues

Happy Hunting

Dave

[Destroyer-Dan]

Thank you mate you’ve been super helpful 

[Destroyer-Dan]

I forgot all about the thread in the end I just removed all the trailer harness as it was so bad it wasn’t worth trying to repair so my car has lost one feature for now but in the future I will replace it I just forget about it as I don’t use the car to tow anything ever 

[Greydog]

Thanks for the update Dan

Dave