Electric brakes problem
Submitted: Thursday, Sep 15, 2011 at 11:39
ThreadID:
89032
Views:
5868
Replies:
5
FollowUps:
11
This Thread has been Archived
Scott P1
Hooked up our new trailer for first time and module installed by VW cooked within 1Km of towing. Had new module installed but controller was playing up and module No. 2 had cooked about 2hrs into first trip. Had four auto elecs
check wiring and all agreed nothing wrong with wiring. Replaced module for a third time and replaced controller. Now 1700kms into our camping trip (and actually on the way back
home) and controller starting to play up again, controller reading when brakes not applied and brake lights stuck on, even when car is off. Car new only 6 months old, trailer new only 3 weeks old, no idea stuck on side of road and no-one thinks it's their problem. Everything is under warranty but can't figure out who to call - trailer guy, Volkswagen or guy who intalled electric brakes???? We'd appreciate any help/suggestions.
Reply By: Member - Phil G (SA) - Thursday, Sep 15, 2011 at 13:32
Thursday, Sep 15, 2011 at 13:32
VWs are incredibly compicated when it comes to trailer and brake controller wiring - they sense blown bulbs, disable reverse sensors, and I believe have something to do with the VSC. Our Tiguan has a dealer fitted factory towbar and wiring (costs about $2000 and most of that cost is the electronics), but we bought it 2nd hand, so don't know whether any issues were sorted before we bought it.
But I fitted the controller and to overcome any potential hassles, I ran the brake controller sensing wire all the way back to the 7 pin trailer plug, so I bypassed the complicated stuff and received the same signal as the brake lights on the trailer. Seems to work fine, but only fitted the controller a couple of weeks ago, and you have me worried that something might fry when we take it away next week.
The VW watercooled
forum is worth a look as
well - electric controller wiring issues are common in most VWs.
http://www.vwwatercooled.org.au/forums/forum.php
AnswerID:
465075
Follow Up By: Scott P1 - Thursday, Sep 15, 2011 at 15:26
Thursday, Sep 15, 2011 at 15:26
Hi Phil
We have a 2011 Multivan and the tow bar and wiring were all done by the dealer. I hope you don't have the issues we're having. Maybe we'll have a solution by then. Posted more details in reply to TerraFirma.
Cheers
Scott
FollowupID:
739047
Follow Up By: Member - Boo Boo (NSW) - Thursday, Sep 15, 2011 at 16:43
Thursday, Sep 15, 2011 at 16:43
G'day Phil
I bought a new Dmax yesterday and when I asked about the wiring for a brake controller he said to get the installer to run the wiring from the wiring that connects to the 7 pin flat plug near the towbar.
Perhaps this avoids having to cut into wiring under the dash and possibly upsetting something.
FollowupID:
739054
Follow Up By: Member - Phil G (SA) - Thursday, Sep 15, 2011 at 16:54
Thursday, Sep 15, 2011 at 16:54
Gday Boo Boo,
The VW has no switch at the brake pedal - its in the master cylinder.
Maybe the DMax is the same.
Hope you enjoy fitting out the DMax - a new vehicle is always fun.
Cheers
phil
FollowupID:
739057
Reply By: Roughasguts - Thursday, Sep 15, 2011 at 19:04
Thursday, Sep 15, 2011 at 19:04
I think they got there wires crossed.
There are two power wires one from the battery that should go to a 20 Amp auto re set circuit breaker that shouls be a 6MM wire!!!!! goes to the controller.
Then one from the brake light of the tow vehicle back to the controller another 6mm wire, then from the controller to the blue wire 7 pin plug and then to the trailer all should be 6mm.
If they crossed these wires, there might be your problem with the controller reading brakes have voltage when there not actually on.
Also might be the problem as to why it's cooking the controller.
Cheers.
AnswerID:
465116
Follow Up By: Scott P1 - Thursday, Sep 15, 2011 at 20:09
Thursday, Sep 15, 2011 at 20:09
All been checked and wiring all good. It's the module getting cooked and the trailer brakes which have separate wiring only picks up from the brake light from trailer plug on the car, which is after the module. The brake controller is fused from the battery and as an auto reset mini CB.
Do you think there could be an intermittent short in the trailer wiring or a faulty earth?
Scott
FollowupID:
739083
Follow Up By: Roughasguts - Friday, Sep 16, 2011 at 05:29
Friday, Sep 16, 2011 at 05:29
Hmmm you know I'm not keen on the pick up for module from the trailer plug cause that wire ends up running the brake lights on your van it may be a bit much of a load on small wire capacity.
Not only that the wires in that plug are very close together and there is no room to double up the amount of wires in there, and any fraying of the wires in the plug can cause a short ! the wires may fray in a short time due to just putting the plug in and taking it out. So I would still take the feed from a brake light.
There are bad Earths in trailers for sure if the Earth is not taken from the car 7 pin plug you cant rely on the tow ball carrying the Earth load, especially if the load is high. EG: an old properly wired trailer can still have the tail lights flashing if you put the indicator on! Problem is a bad Earth clean up the Earth and all is good.
Cheers.
FollowupID:
739116
Follow Up By: Scott P1 - Friday, Sep 16, 2011 at 11:15
Friday, Sep 16, 2011 at 11:15
Ruled out earth problem as it is earthed back to the battery.
Cheers
Scott
FollowupID:
739139
Reply By: member - mazcan - Saturday, Sep 17, 2011 at 14:39
Saturday, Sep 17, 2011 at 14:39
hi scott p1
the electician who you say made a connection to the rear tail light has made a very wrong connection as i have had serious problems due to this been done to my 2005 golf by a towbar installer in
adelaide who claimed to know what he was doing and that connection eventually after several thousand km's and a lot of weird things going on within
shut down my vw golfs cpu engine management system on road and vw evenually traced the problem to the fact that wiring connections were made directly to the back of the rear lights it was all disconnected and the proper wiring modules were installed for the vw and have had no more issues
so i would get that wire disconnected quick smart
you can not connect any wiring to the leads that are on tail /park/reverse or turn indicators left or right side in the boot like used to to be the way it was done in the past years on vw at all....
wiring connections have to go through the special computor modules that vw supply with the towbar system and i had to buy an extra one so i could tow my 6x4 trailer its an inline module with plugs attached for that purpose any accessories that i have put in for my camper trailer come directly off the battery through a relay and it own master switch i have installed heaps of extra wiring this way with out any problems including twin charger for camper trailer and several 12v sockets for auxillary lights /gps/ phone chargers etc you cannot take a connection off the vw key either without a computor module being inline first so be warned
my vw has 95000km's on the clock so i speak from experience
my guess is the electrian who installed your brake controller has made an error in connections and the others who have looked at it cant see the
forrest for the trees and are just agreeing with each other which is so often the case if none of them really know about vw systems
but probably wont admit to it
there are electricians and there are electrians as i found out the expensive way
mine wasnt covered by warranty because of the wrongful connection and cost me $900 yes ouch!
cheers barry
AnswerID:
465277
Follow Up By: member - mazcan - Saturday, Sep 17, 2011 at 15:21
Saturday, Sep 17, 2011 at 15:21
hi scott
has anyone traced the wiring for the electric brakes from the trailer plug back through the harness to the electric brake pads and made absolutely sure that the wires aren't pinched together or crossed over causing a direct short and why isnt the fuse blowing first before the controller melts down is there an inline fuse anywhere in the the wiring system one would hope so
quiet often the trailer section of the wiring from the plug rearwards does get damaged by simply backing into it which can pinch or damage the wires inside the harness
without actually been obvious to the eye and can be easily be overlooked thats why i have suggested the above even testing continuity doesnt always reveal it as they can cross over when they are pinched together inside the harness and still give a continuous reading
just my thoughts from a lifetimemany towing km's of these sort of problems
cheers barry
FollowupID:
739268