Trailer Wiring Nightmare!

[Peter041]

Well I converted to Landrover from Toyota about 3 months ago, and couldnt be happier with my Discovery 4 (3L V6). Great motor, gearbox, interior, looks, everything works so well and is just so good... except my trailer wiring.

My trailer is a boat trailer, it uses electric/hydraulic brakes that have a live wire (direct from car battery) to charge the break away system battery. Other than that it runs standard earth/brakes/indicators/lights on a 7 pin plug (not the original, as this was filled with resin and could not be rewired).

Problem; the vehicle will not detect the trailer attached, so the reversing beepers stay on when reversing. I think it is because I have non standard wiring. Also because it wont detect the trailer, I dont think the trailer stability assist will be working.

Any suggestions of an easy fix? Or is it a job for the dealer?

[SuperMono]

LED lamps on the trailer?

[Peter041]

Yeah, LED's. Does this make a difference to sensing the trailer is connected?

[outasight]

Yes!

Read these threads for far more useful info ...

http://www.aulro.com/afvb/d3-d4-rrs/85396-led-trailer-lights.html

http://www.aulro.com/afvb/d3-d4-rrs/132337-d4-led-caravan-lights.html

Regards,

Les.

[Mick_Marsh]

Could.
LED tail lights have such a small load the indicators need an in line resistance so the flasher can will work correctly.

[austastar]

Hi,
LED lamps have a high resistance and thus a small current draw.
Not enough Amps being used to trigger the older style of bimetalic flasher can or perhaps trigger the vehicle trailer sensing system.

That is if LEDs are causing the problem.

cheers

[Peter041]

Thanks all.

With more searching around it sounds like this doesn't seem too uncommonm and the LED's in the trailer just might be the problem, although I'm not getting the blinking or fast flashing the some people report. My trailer lights all work OK, its just the vehicles doesn't sense the trailer as being attached.

If it is this, then it sounds load resistors in the indicator and brake circuits are needed on the trailer. I'll go to Supercheap tomorrow and buy 3 of them and fingers crossed that fixes the issue ...

[101RRS]

In your original post you imply you are not using the standard plug fitted to to the car "as it was resin filled" - how exactly is you 7 pin plug wired into the car - when used with incandescent trailer globes the OEM wiring is linked into the computers and switches off rear sensors and a whole lot of other things and on the D4 turns on towing assist.

Now if your trailer plug is bypassing the OEM system then the computers will not know there is something attached and switches nothing on or off even though your trailer lights will work.

Why didn't you use the OEM socket - adapters are available from Super Cheap and I use one on my box trailer - it works fine (be aware the Disco is wired to the European spec so there is not one power wire that feeds both tail lights but has one power wire for each tail light - when matched to a aust spec wired trailer with electric brakes it means one of these tail light feeds is plugged into the trailer brakes so when you turn on the lights the trailer brakes come on.

Now as you said the OEM plug is full of resin and cannot be tampered with but somewhere in the back is a trailer wiring loom fuse box (I have a RRS so do not know where it is in a disco) so you can cut this second trailer light feed wire and feed in what you want (electric brakes ;) feed). Also on the standard 7 pin plug there is a facility for reversing lights and aux so these can be used to feed the break away battery - just not sure whether there are any spare slots on the fuse box and OEM socket.

Clear as mud????

Then we need to look at the LED issue - don't pick on the Landy for this - the new VW Amorak is the same but woulodn't you think the importers would Australianize the cars before sale.

Garry

[driftn69]

G'day,

There is a short but useful video on the LRA web sight that explains the operation of tow assist and how it's activated. Discovery 4 Photos & Video | Land Rover Australia (http://www.landrover.com/au/en/lr/discovery-4/photos-and-videos/)

I used a Dremel to remove some of the resin so I could run the electric brake wire direct to the correct pin, (don't like joins) then repacked it with silicone.

Cheers Colin

[Stuck]

If what you're trying to do is disarm the reversing sensors when you have a trailer connected (so the sensors don't think that you're about to reverse into the trailer) there was a plug available that had a set of contacts which would open, cutting power to the sensors, when the cover on the plug was opened. These were fitted to genuine Holden trailer harnesses for use with their reverse sensored cars I think around the time of VX / VY Commodore. From memory they were made by either Brylite or Lumen but don't hold me to that. Have a look at reply #7 in this thread http://www.google.com.au/url'sa=t&source=web&cd=11&ved=0CC4QFjAAOAo&url=http%3A%2F%2Fforums.justcommodores.com.au%2Fvz-holden-commodore-2004-2006%2F161393-vz-calais-faulty-reverse-parking-sensors.html&rct=j&q=lumen%20trailer%20plugs&ei=iIqHTvf1E-SjiAfQzaSWDw&usg=AFQjCNGtt6xS7x3oEMsjkeJhrbpSIDbA6Q&cad=rja

Cheers,
Anthony.

[CaverD3]

Being an LED trailer you will need a shunt pulse or similar device.
If it is not detwcting the trailer maybe the dealer didn't enable the towing electrics?

[tonys tank]

A had a shunt device (very expensive and clumbersome) however have replaced it with a pair of load resistors (cheaper and easier) wired into the 2 x indicator wires and earthed. A lot easier and always there. I have now placed load resistors on all 3 of my trailers. These resistors work well

[Peter041]

In your original post you imply you are not using the standard plug fitted to to the car "as it was resin filled" - how exactly is you 7 pin plug wired into the car - when used with incandescent trailer globes the OEM wiring is linked into the computers and switches off rear sensors and a whole lot of other things and on the D4 turns on towing assist.

Now if your trailer plug is bypassing the OEM system then the computers will not know there is something attached and switches nothing on or off even though your trailer lights will work.

Why didn't you use the OEM socket - adapters are available from Super Cheap and I use one on my box trailer - it works fine (be aware the Disco is wired to the European spec so there is not one power wire that feeds both tail lights but has one power wire for each tail light - when matched to a aust spec wired trailer with electric brakes it means one of these tail light feeds is plugged into the trailer brakes so when you turn on the lights the trailer brakes come on.

Now as you said the OEM plug is full of resin and cannot be tampered with but somewhere in the back is a trailer wiring loom fuse box (I have a RRS so do not know where it is in a disco) so you can cut this second trailer light feed wire and feed in what you want (electric brakes ;) feed). Also on the standard 7 pin plug there is a facility for reversing lights and aux so these can be used to feed the break away battery - just not sure whether there are any spare slots on the fuse box and OEM socket.

Clear as mud????

Then we need to look at the LED issue - don't pick on the Landy for this - the new VW Amorak is the same but woulodn't you think the importers would Australianize the cars before sale.

Garry

Hi Garry
The problem with the OEM trailer plug connector being resin filled, was that I was therefore unable to run a live wire to the trailer which I require to power the breakaway system battery. Also had to wire the brake controller into the system which also meant plug mods. Much easier just to remove the plug and replace it with one that can be wired to suit.

Note this is a very standard change to wiring that many caravans etc need to adopt, whenever they have a brake controller and live wire feed installed.

I'm aware there are other plugs in the wiring loom but seemed an easier fix to replace the plug and insert the required wires, and yes, it all works perfectly OK - almost ... except the vehicle doesnt know its all there.

I'm hoping that the fitment of a couple of load resistors will in fact allow the vehicle to sense the trailer attached and if so, all will be OK. If not, then I am guessing that I'll need a LandRover technician/autoelec to sort it out.

Either way, its a fairly annoying issue for a pretty basic problem, and a slightly more robust approach to sensing a trailer is attached wouldnt go astray in future vehicles (LR, VW and many Euro's I understand have the same issue).

[Peter041]

Bright idea ... before doing anything else I'm going to pop around to a mates place and plug in his trailer which I know is does not have LED lights and see if this activates the D4 to recognise the trailer.

If so, then a few load resistors into the trailer wiring ... fingers crossed this works.

[Peter041]

OK (feel a bit like I'm talking to myself here...).

Tried a non LED trailer and still no dash indicator of a trailer attached, and still the reversing beeper operates.

The problem is in my vehicle trailer plug wiring. Basically the two wires that I DONT have connected to the usual places on the 7 pin plug are:

Blue - the electric brake wire from the car are not connected, rather the brake controller is connected here. This is probably not the issue as many simple trailers would not run electric brakes.

Black - the reverse wire is disconnected, in its place is the 'live wire' supply direct from the battery to enable trailer brake power. This I suspect is probably the issues as the vehicle would expect to operate the reverse lights on the trailer through tail lights, and a load on this circuit would be expected.

My theory is that one of these circuits - probably reversing - needs to be seen by the vehicle to activate the sensing of the trailer, and/or load resistors are required in the indicator/stop circuits as well if the LED current draw/resistance issue is in fact a real issue...

NEXT QUESTION - who knows a good Auto-electrician in Melbourne SE suburbs who knows the D4 3.0 systems well?

[baldivistribe]

Its ok im here listening and learning. I will have all this to look forward to soon.
I have been told many different things by salesman and service people.
So by you doing all this is saving me doing it:)
cheers
steve

[outasight]

NEXT QUESTION - who knows a good Auto-electrician in Melbourne SE suburbs who knows the D4 3.0 systems well?

Peter041,

I live in Langwarrin, and I am happy to take a look at what you have done/not done & you can confirm things easily using our regular incandescent globed caravan which is working perfectly with my D4 SE using Sniegy's instructions.

I'm an electronics technician with good mechanical knowledge as well.

PM or email me if you want to come down & I'll help get it sorted for free.
Will be at Leasurefest Saturday though ;)

Regards,

Les.

[Peter041]

G'day Les, thankyou thats a very kind offer. I work over in Seaford so might just take you up on that offer. Will be in touch via PM.

[outasight]

G'day Les, thankyou thats a very kind offer. I work over in Seaford so might just take you up on that offer. Will be in touch via PM. Daylight savings is here, so even one afternoon after your work may be good if we set a day so I can be more sure to be home earlier.:cool: