Thread: Disco4 towing question

I would guess that your headlights turned on when the brakes locked up. The standard plug wiring has pin 5 as right hand side light:
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Australian wiring is pin 5 is the service brakes:
trailer-wiring-7-pin-large-round-plug-and-socket.png

You could be on the money shane - thanks

just when this happened i was actually just going under a overhead tunnel passage (short one) but perhaps the headlights which are on 'auto' came on causing the brakes to lock up. but could you explain this more to me?

why would the headlights coming on activate the elec brakes on the trailer? in theory I cannot use headlights when towing then? seems strange to me but you are correct in your reading of the situation. i might try it at home and turn on the head lights and see what happens with the elec brakes on the tvan as a test. thanks again

Originally Posted by shamirj

You could be on the money shane - thanks

just when this happened i was actually just going under a overhead tunnel passage (short one) but perhaps the headlights which are on 'auto' came on causing the brakes to lock up. but could you explain this more to me?

why would the headlights coming on activate the elec brakes on the trailer? in theory I cannot use headlights when towing then? seems strange to me but you are correct in your reading of the situation. i might try it at home and turn on the head lights and see what happens with the elec brakes on the tvan as a test. thanks again

In Europe trailers have two light circuits (Left and right), and use pin 5 for the second circuit. Dealers were meant to modify the vehicle tow wiring so that 5 pin was left disconnected, ready for an EBC.

See this thread D4 Electric Trailer Brake Wiring

Originally Posted by shamirj

why would the headlights coming on activate the elec brakes on the trailer?

All the brake controllers do is supply a variable voltage to the brakes - if that circuit is being activated when the headlights turn on then you'll be getting full voltage to the trailer brakes.

so what are my options apart from a brake controller.

in the interim what can be done to just allow me to move the camper around - please do not say switch the headlights off
I did have the redarc tow pro elite fitted to my last D4 but it cost around $800. So this time round looking at options where I can fit a brake controller cheaper and perhaps on the trailer itself rather then car mounted. suggestions please

I will test the theory of headlights 'on' and driving the camper to see if the brake lock up when the rain stops...

disconnect the wire on pin 5. Easier to do on the plug on the trailer.

Originally Posted by shamirj

so what are my options apart from a brake controller.

in the interim what can be done to just allow me to move the camper around - please do not say switch the headlights off
I did have the redarc tow pro elite fitted to my last D4 but it cost around $800. So this time round looking at options where I can fit a brake controller cheaper and perhaps on the trailer itself rather then car mounted. suggestions please

I will test the theory of headlights 'on' and driving the camper to see if the brake lock up when the rain stops...

The genuine trailer plug system in the car has its own fuse box in the back of the car - just pull the relevant fuse to what is now the trailer brake circuit - then when the lights come on, no trailer brakes.

PXL_20201123_051639848.jpg

If you just want to move it leave the plug out.. Go near a road without brakes and you'll be in trouble or uninsured if something bad happens. If it's just got standard electric brakes ie, non hydraulic.. Just use a cheap generic red arc controller.. The last one I bought was $150, you can install this yourself with sneigys guide