2012 Passat - Camper Trailer needs seperate Brake wire to drive electric brakes

[Grimmy_xcx]

Hi all

I have a 2012 Passat with a 7 pin flat trailer socket. I'm trying to tow a camper trailer behind it which uses an ElecBrakes Bluetooth module to control/modulate the electric brakes on the trailer. The ElecBrakes unit is powered via the the park light circuit from the trailer socket (so need lights on to power the unit). It then needs to detect braking from the car (e.g. brake lights illuminate) to drive/modulate the electric brakes on the trailer (it has a plug and play adapter between the car trailer socket and the trailer plug). The issue is - it looks like I only have 1 wire for both the tail lights AND the brake lights on the Passat. The circuit runs 6-7v with lights on for tail, then 12-12.5v for brakes (regardless of lights being on or not).

All car brake lights are LED and all rear lights come on when lights are turned on - the tail lights just get brighter when I brake. The only exception to this is the brake light in the tailgate lid (only comes on when braking).

Has anyone experienced this problem/got a solution that doesn't involve going to an autoelec to hardwire a brake controller in via the blue wire (i.e. not using the ElecBrake unit)? The only thing I can think of is using the brake light off the top of the rear liftgate but I don't know what colour wire that is (there are about 10,000 wires going into each side of the lift gate and they're all white), I don't know what voltage it is even if I found it (ElecBrakes need 12v min), and the ElecBrake unit drops connectivity whenever I hit the brake as the surge from 6v to 12v on the tailight wire is resetting the connection.

Is there a smart ECU or something I can get which decifers tail from brake lights and gives me an extra wire??

Gareth


Edit:
ElecBrake is this > Elecbrakes Electric Trailer Brake Controller - ELBC2000-PS - Auto One
Elecbrake Adaptor is this > Elecbrakes Plug and Play Adapter Flat 7 Pin To Flat 7 Pin - A7-7 - Auto One
Photo attached of right tail light wires when we had it apart.

[Guest001]

Would be easier to get a Redarc TOWPRO ELite and not worry about all the bluetooth crap working or not If your trailer is under 2 T it can just use over ride brakes which work simply and easily without all the fancy stuff. A camper usually just has over ride from the factory. Sounds like you are making expensive work for yourself when a cheaper simpler system would work properly. Im very sure I wouldnt have brakes relying on a dodgy bluetooth connection. Value my life and partners life too much

[Grimmy_xcx]

Don't really want to get into disagreements about peoples opinions on this unit. It's on the car, the camper is downball 70kg and atm is sub 1250kg. If the car had a red wire into the plug it would work fine. The failsafe for the bluetooth are numerous - all the bluetooth does is modulate the pressure. If the bluetooth drops out it saves the last setting and applies the brakes at that level. If there is no bluetooth or the bluetooth to 7pin adaptor is cut/pinched/damaged/shorts then the red wire from brakes into red wire 7pin trailer plug applies full force brakes (unmodulated - not ideal but better than no brakes).

There are literally thousands of users with this system and positive reviews. I am also certain that a hardwired Redarc/any of the other numerous brands and models I saw mentioned while trawling this forum are a better know/used/recommended option but this one (if it is possible to make it work) would suit me fine.

[MIG]

Does your Passat have the factory towbar? The trailer module lives behind the passenger side boot liner, it has provision for power brakes and battery charging via non-populated connector.





Blue is the connector, and red is the trailer module.


Just remember the Passat has a tow ball limit of like ~85Kg so make sure your camper is below that

[Grimmy_xcx]

Thanks MIG - no it is a Trailboss bar and was being wired in through the rear right tail light cluster. It seemed to be the easier side to get into for the installer (Towbar Discounts) so thats where it landed. Not sure what car you photo is from (my battery is in the engine compartment) so not sure if it's the same for my Passat having that module in there or not

[MIG]

Yer running it from the LED lights will give you issues; those lights run PWM to control the brightness, creating a very noisy power feed.


The best solution would be to run a factory towbar module and connect your 7-pin plug to it; the module has dedicated lines for all the lights and lets the car know when you are towing (eg disables liftgate and parking sensors), to my knowledge, the B7s are prewired for this module on that left-hand side, you would need to get a 1K0 907 383 F


Another solution (a bit of a hack job IMHO) would be to run a power feed from (terminal 15 lighter socket) in the boot for your constant power and 3rd brake light for the brake signal. I will check the wiring diagram tonight, but I think that feed is also via the left side.


PS: Batt is in the boot for the V6, engine bay is too full

[Grimmy_xcx]

Thanks again MIG, just called VW parts. That part is on backorder and 8-10weeks off in Germany for a lowly $1102 😂

Also RE your earlier comment:
"it has provision for power brakes and battery charging via non-populated connector" - the Elecbrakes replaces the need for the normally blue hardwired power brakes but does so by using brake signals from the normally red brake light wire sending a signal to the unit. So unless that module has a dedicated red (or whatever colour VW use for their brake signal) it still wouldn't be compatible with the Elecbrake 😭

[MIG]

Thanks again MIG, just called VW parts. That part is on backorder and 8-10weeks off in Germany for a lowly $1102 ��

Junk yards have them for about $100, eBay about $120, it provides all signals to the normal 13-pin euro-style trailer plug


Volkswagen Passat B7 - Wiring Diagrams -vw-passat-b7-wiring-diagrams-eng.pdf

Check out page 300 onwards, J345 is the module's name.

[Umai Naa!!]

Need to pull the brake light signal from the travel sensor on the master cylinder.

[Phillbies]

Hi MIG, hoping you're still on here. I installed a used Westfalia tow bar on my 2013 Passat. It have the wiring loom from 7pin flat connector to the module and i was very happy to find the other end above the left wheel well. I didn't avhe the module so I purchased one from Ebay (1K0 907 383 F as you've mentioned). After installing the tail lights and brake lights are working and the sensors disable but the indicators don't work. Do you know if this is a coding issue? Does my car need to be coded to fully acknowledge the new control module?

[MIG]

I think there will be two parts to finish that off,

1. When the dealers fitted those kits, there was a jumper to connect the can bus to the rear (can signals don't like disconnected ends) 5N0055204N, here is a guide to make one up https://www.vwvortex.com/posts/115860071/ or you can splice the lines, this connects at the BCM, right above the accelerator pedal you will find a connector. you may have done this already (The brake lights go direct for safety, so that might explain why those work)

2. Coding, Trailer Hitch Retrofitting (3C) - Ross-Tech Wiki
The main parts are,
- Register 69 - Trailer in the gateway
- parking sensors and RVC coding updated.
Don't worry about the Trailer Stabilization coding, which was not approved for use in Aus.