MF 390 relays?

[Still Farming]

Maybe??

 

[Dry Rot]

II just pulled the suspect relay to compare it with one on Ebay that I've bought.

Out of curiosity, I tried the light switches without the relay in the socket. The side lights worked and the buttons were illuminated! So clearly, the relay is faulty and I assume the points have become welded. Anyway, it looks as if replacing that relay will solve the problem! Fingers crossed.

This is the relay on Ebay:

Classic Mini Dim Dip Control Relay Unit YWC10050 pink land rover Lucas | eBay

Part Number - YWC10050. This sale is for ONE unit. These fit under/behind the dash and are colour coded pink.

www.ebay.co.uk

 

[Pheasant Surprise]

I don't think relays are that easy to check so I may just bite the bullet and buya new one and see if it makes any difference. I think they are meant to 'click' if they are working. There is no click. The other relays (that I can find) are working.

Should be pretty easy to check continuity with a multimeter. You may find the contacts inside get pitted with age/use. That’s normal and a common failure point, as they can fuse/weld themselves together.

Traditional coil type relays will “click”. New generation solid state (electronic) relays use high power transistors to switch and are hence silent. But I don’t think you have those.

 

[Dry Rot]

Should be pretty easy to check continuity with a multimeter. You may find the contacts inside get pitted with age/use. That’s normal and a common failure point, as they can fuse/weld themselves together.

Traditional coil type relays will “click”. New generation solid state (electronic) relays use high power transistors to switch and are hence silent. But I don’t think you have those.

I am pretty sure it's the relay though I am not electronically savvy enough to work out why the lights work with the relay removed but not when it's in place. I'll dissect it and perform an autopsy when I have the replacement working.

 

[Dry Rot]

The replacement relay arrived today.

I installed it and now the side lights work, the horn works, the instrument and display lights work, and dip and full beam works. Yipee!

If I had a £1 for every hour I've worked on this, I could have purchased a new tractor. But it is nice when a plan comes together!

Thanks everyone for your contributions. Since three major MF dealers didn't know the answer, I count this as a significant victory! The relay is readily available and costs around £20 including postage.

Classic Mini Dim Dip Control Relay Unit YWC10050 pink land rover Lucas | eBay

Part Number - YWC10050. This sale is for ONE unit. These fit under/behind the dash and are colour coded pink.

www.ebay.co.uk

 

[Dry Rot]

I was going to close this thread here, but as usual life is never easy and I have leant a lot and hopefully the information will be of use to someone. The saga continues!

The YWC10050 relay seemed to work so I dissected the old one (which didn't!). Photo below. The reason it wouldn't have clicked when activated is obvious from the picture. It is a solid state relay and has no moving parts!

All the lights now work as they should -- except the lights that indicate gear range selection don't now. This is a 12x12 shuttle tractor, so the gear range (1,2,3, or N) is selected by operating the gear lever on the right hand side, then gears are selected as normal by moving the lever on the left hand side of the 'slot' as normal. The range selected is displayed by illuminating one of the figures above on the panel. So no gears and no tell tale lights and the tractor won't go into gear.

Well, the solenoid operating the gears is obviously not getting power. So that is this mornings project! As the tractor arrived with fascia panels loose, someone was obviously fiddling with electrics before it arrived here, so it looks like it is going to be fun! I fitted a third service to the loader a while ago and when taking the loader of, I broke the cable to the third service solenoid, so that might also have shorted something. I can't see any burning inside this relay, so perhaps someone simply used the wrong one? Incidentally, this is a fairly standard 'dim-dip' relay used in Land Rovers, Minis, MGs, etc. but of course one used in tractors might be different.

Inside the "old" relay:

 

[Pennine Ploughing]

my memory is on holiday again,
but something tells me, is there a contact switch on the clutch pedal, it has to make contact to change gear, as I think there is a selector shaft lock to stop it jumping out of gear, and you may of put out of gear while working on it, and cannot get it back in
also if the 18p spring breaks, if you play with the gear stick a few times back n forth, it will go into neutral and stay there, but unlikely its that

 

[Dry Rot]

my memory is on holiday again,
but something tells me, is there a contact switch on the clutch pedal, it has to make contact to change gear, as I think there is a selector shaft lock to stop it jumping out of gear, and you may of put out of gear while working on it, and cannot get it back in
also if the 18p spring breaks, if you play with the gear stick a few times back n forth, it will go into neutral and stay there, but unlikely its that

I pulled the relay (YWC10050) this morning as some of the lights work without it and -- hey presto! -- the tractor now goes into gear, but the tell-tail lights showing power range do not light. So I think the problem is with that relay. I also read that solid state relays canot be tested with a multimeter. I need to use a test light.

I have the Operator Manual (1856 706 M1) for the 300 series tractors which seems to have the correct circuit diagram. I have access to the Workshop Manual through a Facebook group (https://lookaside.fbsbx.com/file/30...IGvbwAh2PMk2uWBCrUExFDpNFmvfYuclg32KiRsZlkrIw). The picture of these three relays in the manual is completely different to my tractor so I am thinking it has been tampered with.

 

[Fievel Farmanimal]

I have that kind of black relay in my synchropower 390, which don't need electricity in gear changing. That could be for older model? Are there any markings on those transistors? That don't look too complicated to build a new one.

 

[Dry Rot]

I have that kind of black relay in my synchropower 390, which don't need electricity in gear changing. That could be for older model? Are there any markings on those transistors? That don't look too complicated to build a new one.

I am still scratching my head here! No everything seems to work without that relay installed. I need the help of an auto electrician. There are no meaningful markings on the relay, just Lucas 12V.

I think my tractor was made in 1992. The relays are not as illustrated in the Workshop Manual which also says there are relays under the shelf to the left and to the rear of the near side door but I took that off today and there is nothing there!

 

[Dry Rot]

To close this thread, if anyone is still reading (!), I finally worked it out. Sorry, but it annoys me if I can't solve a problem and I become even more persistent!

This one was complicated by a bad connection under the dash causing an intermittent fault. Fixed that and the lighting began to work in a logical way. That unidentified relay controls some of the lights and dims others (range selector lights and switch lights) when on full beam so the driver isn't dazzled. That accounts for almost everything working when it wasn't even plugged in!

It isn't a relay with seven functional pins either but a five pin relay with two additional locating pins (so seven in total, but two are not connected to anything).

Simple when you know, isn't it?