Thread: D4 Electric Trailer Brake Wiring

Originally Posted by Nod

Thanks Peter. Yeap... looks like Excel. If you update... please just post back under your name.
Gordon

[EDIT] Peter, after reading another post were Scott referred to 12S & 12N sockets... and a google search validated.... this is the correct name for the 7 pin sockets.

Sorry, but I just think that it is a common error and not one that should be promoted.

Originally Posted by Learner

Sorry, but I just think that it is a common error and not one that should be promoted.

Wrong. The 12N/12S terminology is straight from the Land Rover Electrical Wiring Diagram (one example below) and parts catalogue.

Hi LRD414,
Thanks for the correction.

I must admit, however, that I can't see the logic in that nomenclature.

Best Wishes,
Peter

PS: It's just as well that LR NEVER made an error in their printing.

I have replaced the 12N and 12S trailer plugs with a flat 12 pin trailer socket with reed switch (Narva 82074BL). Using the reed switch on the trailer socket plug enables the D4 to automatically recognise a trailer and activate all the trailer mode functions only when a trailer is plugged in.


The Anderson is on the end of the Traxide cable in a Trailer Vision Anderson SB175 Weather Proof Cover.


The 12 pin socket wiring is a combination of the original 12N and 12S harnesses and builds on what others have done earlier in this and other threads but automates “trailer recognition”. I started with a Linear Electronic Design Adapter module (LEDA) which is tucked under the rear aircon, behind the tow bar storage. This was just easier than mucking around with resistors, mountings, heat sinks and so on. The module taps into the yellow and green wires on the trailer harness as described elsewhere and in the LEDA's instructions and its on/off cable connects to a relay powered through the reed switch on the trailer socket. So whenever the trailer socket cover is opened, the relay activates, the module turns on, and the system sees a trailer has been attached. So no manual switching to remember to turn on or off or having the D4 permanently in trailer mode.


Warning: For no good reason I wired the socket as a plug - it was dark OK! Ha! So the wiring is a mirror image of what it should be. But it works on the camper and the boat so I’m happy. I may fix it sometime, but it is a big job as it’s all sealed now and the harnesses are quite short.


Power to the LEDA is from the old 12S harness ignition feed 12V red/white terminated on Pin 9 then via the pale blue jumper to one side of the reed switch. The other side of the reed switch feeds the relay via one of the 12S harness white earth wires that was surplus to my needs, identified by a bit of red tape at each end.


I used an ignition feed 12V so that there is no power draw when stopped for the night with the camper still plugged in. Only downside is that the D4 asks if a trailer is attached every time the ignition is turned on.


Trailer electric brake feed from the TowPro is the heavy black wire on Pin 5 between the red and white wires.


The red wire on pin 12 is a spare 12V feed from the second battery if ever required.


Next step is to make a cable for the CTEK battery charger or solar to power the blue/pink 12V battery feed from the 12S harness now on Pin 8.


In the last image you can see the ½ circle bit of red insulation tape used to stop the sensors detecting the Mitch Hitch. Looks a bit rough but very hi tech and works well.

Andrew

In the original post it recommends running a white wire to the -Ve battery terminal. If I am mounting a Redac Tow Pro in the drivers side kick panel can you run the -Ve wire (white) to the earth point located there or do you need to take it to the battery as described?

I have in the back if my mind that I read somewhere that nothing should be attached to battery earth connection.

Read further down in first post. Earth post in front of battery is the suggested point for -ve connection. If another earth post is more convenient I wouldn't have thought there would be any difference.

Scott

Saw that Scott but I just put in my Traxide cabling and Tim points you to an earth point behind the kick cover. I ran a black 3mm wire to battery and was going to pick up the earth inside used by Tim. I was also thinking there would be no difference.

Still rereading all the thread - what size circuit breaker did you use?

Found it - 25 Amp

Any earth stud is good.... the metal body is a heavy duty wire!