Alternator wiring (Leyland 272)

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KGraham
Posts: 15
Joined: Tue Jun 04, 2019 3:06 am
Canada

Alternator wiring (Leyland 272)

Post by KGraham » Tue Jun 04, 2019 11:18 pm

Hi,

I just bought a Leyland 272 tractor and the battery drains over night (new battery) If I disconnect the black wire with the yellow spade connector the battery will not drain. Can anyone look at this picture and tell if the wiring seems correct. Trying to figure out if the wires are correct on the alternator prior to me looking into a bad diode within or a parasitic draw elsewhere. When I bought the tractor I was told the alternator was recently replaced.

Thanks,

Kayle
Image



KGraham
Posts: 15
Joined: Tue Jun 04, 2019 3:06 am
Canada

Re: Alternator wiring (Leyland 272)

Post by KGraham » Thu Jun 06, 2019 12:29 am

Can anyone confirm if this wiring diagram is accurate.

Thanks.
Image

Nowtnew
Posts: 82
Joined: Sun Apr 01, 2018 8:49 am
Great Britain

Re: Alternator wiring (Leyland 272)

Post by Nowtnew » Thu Jun 06, 2019 8:56 am

Hi
That is the wiring for a 'battery sensed' configuration. 3 wires.
Mine has 2 wires, like yours except there is a loop between the two vertically adjacent terminals where the black wire is connected. This is achieved within the connector plug which you don't have. I assume your black wire is the charge warning lamp wire and is switched by the ignition switch? If this wire is permanently live it would account for your drain. It looks suspiciously thick to be original.

Regards

KGraham
Posts: 15
Joined: Tue Jun 04, 2019 3:06 am
Canada

Re: Alternator wiring (Leyland 272)

Post by KGraham » Wed Jun 12, 2019 2:39 am

Hi Nowtnew,

Thanks for the response, are you able to send me a picture of the back of your alternator?

So the wiring on my alternator right under where the black wire with the blue connection is plugged in, has 12 volts coming off the alternator at all times. The black wire with the yellow lead was plugged into that which was going to ground causing the battery to die. Further to that my alternator will only charge with that black wire with yellow connector plugged in that section. So currently I am disconnecting that wire every time I am done with the tractor.

KGraham
Posts: 15
Joined: Tue Jun 04, 2019 3:06 am
Canada

Re: Alternator wiring (Leyland 272)

Post by KGraham » Wed Jun 12, 2019 2:56 am

See attached picture
Image

Nowtnew
Posts: 82
Joined: Sun Apr 01, 2018 8:49 am
Great Britain

Re: Alternator wiring (Leyland 272)

Post by Nowtnew » Wed Jun 12, 2019 9:29 am

I'll try to get you a photo later. Meanwhile, it seems logical to assume that the problem is that you need to provide the correct feed to replace the black wire.

As you have noticed, you need a live feed on that terminal to 'kick start' the alternator into generating. However this has to be switched off to prevent current flowing when the engine is stopped. The correct circuit takes a feed from the ignition switch ( switched side) via a bulb (the charge warning light) to the terminal. Thus there is only a feed when the 'ignition' is on and the bulb glows until the back pressure from the alternator cancels it out thus showing that the alternator is charging. Confusingly, if the 'ignition' switch is switched off with the engine running then the light will glow again as all the ignition auxiliaries are being fed via the bulb. Hence the alternator will still be charging but the no charge light will be on.


Looking at the various circuit diagrams on the club website, I have found that the one which actually matches my 270 the best to be the one for the 285:

https://www.thenuffieldandleylandtracto ... 202100.pdf

Regards
Image

KGraham
Posts: 15
Joined: Tue Jun 04, 2019 3:06 am
Canada

Re: Alternator wiring (Leyland 272)

Post by KGraham » Wed Jun 12, 2019 11:08 pm

Thanks so much. I've ordered an indicator light with as close of specs as the original based on what I could find online. My dash components (except for the mechanical driven tach) do not work and the dash panel does not want to come apart so hopefully the auxiliary indicator will do the trick. If not I'll have to drill out the dash bolts which someone has stripped, half come out half turn but won't come out, trying to avoid opening up that nightmare.

Cheers,

Kayle

KGraham
Posts: 15
Joined: Tue Jun 04, 2019 3:06 am
Canada

Re: Alternator wiring (Leyland 272)

Post by KGraham » Thu Jun 13, 2019 12:26 am

If the indicator light doesn't work, I'm just going to put in a diode so the black wire doesn't feed back to ground but will allow 12volts to the indicator connection on the alternator when the key is on, that should solve the issue in a worst case situation.

Nowtnew
Posts: 82
Joined: Sun Apr 01, 2018 8:49 am
Great Britain

Re: Alternator wiring (Leyland 272)

Post by Nowtnew » Thu Jun 13, 2019 9:26 am

No, that will be futile. (As they might say on Star Trek)The wire feeds power to the regulator and if you put a diode in it wont work. Or rather in one direction it will just be the same as the wire and in the other it will be like no wire! This line must be switched.

This diagram may help as it reveals the purpose of the link wire in the plug. I have no doubt it will work if you follow the switched feed via bulb approach. The wire in this part of the circuit can be light. It only carries less than an Amp (providing the bulb is there) .

When you first switch on there is a small current via the bulb which goes via the regulator to the field coil thus producing sufficient magnetism to get the stator generating. As this builds up the voltage at the terminal via the field diodes increases and takes over the feed to the regulator. In so doing it matches the voltage at the battery and puts out the bulb. Why the two terminals are not connected internally I don't know. Alternator connection conventions are a bit of a minefield.

https://www.lotusmarques.com/info/techn ... or-diagram


Regards

KGraham
Posts: 15
Joined: Tue Jun 04, 2019 3:06 am
Canada

Re: Alternator wiring (Leyland 272)

Post by KGraham » Fri Jun 14, 2019 1:46 am

10-4, indicator bulb it is. I'll let you know how it goes when I'm done, and thanks again.

Kayle

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