MF 390T D Socket Wiring

maco2000 · 13-09-2023 11:27PM #1

Hi folks, there was a 12V socket in the cab that didn't work and it was in the space where the 3 pin D Socket should have been. I have replaced the socket with a new one but there only seems to be two wires to connect. A black wire and a purple wire. Just wondering why is it a 3 pin socket with only 2 wires to connect and if anyone has a wiring diagram for the switch? Many thanks in advance. I don't want to plug anything into it before knowing that it's wired properly.

Cheers guys. 👍

Gillespy · 14-09-2023 07:38AM

There are only two wires in them. Positive on the left, but It’s marked in the socket which is which.

The top pin I think is another live that’s turned on by the ignition. Never seen it used, always just the permanent live.

emaherx · 14-09-2023 07:40AM

It only needs 2 to provide power.

But with 3 wires the small pin is usually connected to ignition auxiliary power so it turns on and off with the tractor. The large positive pin is usually permanent live.

This gives two options while connecting accessories, always on or just on with tractor. If it was a cigarette type 12V socket previously this is why only 2 wires.

patsy_mccabe · 14-09-2023 09:05AM

https://www.boards.ie/discussion/comment/121107538#Comment_121107538

Does the 'always on' go direct back to battery? If so, that can't be safe. A fire risk.

emaherx · 14-09-2023 09:18AM

https://www.boards.ie/discussion/comment/121107742#Comment_121107742

Through the fuse box, it's how most modern tractors are wired.

lakill Farm · 14-09-2023 10:12AM

https://www.boards.ie/discussion/comment/121107742#Comment_121107742

i got a lad to wire a D socket and a cigarette and use charging port onto a small valmet

he wired it direct to the battery but put an inline fuse on it .

emaherx · 14-09-2023 10:40AM

https://www.boards.ie/discussion/comment/121107993#Comment_121107993

When we got the baler / wrapper first none of our tractors had these sockets, Clarkes Farm Machinery at the time sold a complete pre-wired kit with a mounting bracket, it had two loops crimped to connect to the battery at the starter and chassis for earth. There was an inline fuse, just the large +ve and -ve pins was connected, I suspect most retrofitted sockets are wired in a similar way.

lakill Farm · 14-09-2023 10:57AM

https://www.boards.ie/discussion/comment/121108112#Comment_121108112

i had to add D sockets to both the valmet and fastrac . bought little mounting plates in QTP for the D socket

Gillespy · 14-09-2023 11:03AM

George Saunders fit a box to his big TW that has a number of D sockets as well as USB and cigarette sockets. It has a readout of the volts also. I searched but only found ones without the D sockets.

emaherx · 14-09-2023 11:10AM

https://www.boards.ie/discussion/comment/121108215#Comment_121108215

I found this one.

https://cleveragri.ie/product/4-plug-12-volt-usb-port

It's not particularly cheap.

Gillespy · 14-09-2023 11:18AM

The one he has is different. It’s a video from a few years back and it’s not mentioned in the title. That one looks a robust unit. Another usb and a few cigarette sockets would cover all your needs.

MF 390T D Socket Wiring

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