Alternator connections

Resurgam · Sep 28, 2023

I have a new alternator that I bought from Craddock's a couple of years ago which had the correct part number for a 200Tdi. The only screw connectors on the back are marked B+ and W. As far as my limited knowledge of alternators goes these are the battery connection and a connection for a tachometer that I don't have. What I'm missing is a screw terminal for the brown and yellow wire that's supposed to light up the warning light on the dashboard when the alternator isn't charging.

There are various spade connectors, most of which I've established are alternative connections to the B+ terminal. There is a single spade terminal that you can just about see in the photo with a yellow wire which goes to the brush box. Any idea if that's the one I should be using?

dag019 · Sep 28, 2023

that sounds like it is the one you should be using. if all of the other spades are for B+ then it is the only one left as w is for atacho as you state.
It is usually label though D or D+.

mystery · Sep 29, 2023

Connections

Resurgam · Sep 29, 2023

Fantastic. The idiot-proof labelling is just what I need. Much appreciated.

the-prince-e-paul · Oct 30, 2023

Looking for similar advice. I've noticed that my 110 2.5/A hasn't been charging as the battery has been discharging. So I checked the alternator Lucas 127 I think and it has a connector block (see pic), that has three spade connector wires. No other connections are fitted. I checked the voltage in the wires, one was earth I think (yellow!/ green), the centre one gave about 12.4v with engine running or not. The end cable gave only about 12.0v when running hence no charge being created. My other query is that in the dashboard I have no charging little being illuminated either when turning key prior to starting engine or afterwards. I've checked the panel light and it is not blown. Can anyone please offer advice as to where to start. I'm in seden and local Landy garages are likely to be in short supply. Thanks in advance. I'm thi king of buying a new alternator, however I took out the old one and stripped it down and nothing seemed to be wrong, but I'm no expert.
Cheers.
Paul

the-prince-e-paul · Oct 30, 2023

Sorry forgot the pic

tottot · Oct 30, 2023

No earth, that happens through the body of the unit, the small line goes to ignition. Large is power and would give 14vish if working.
The 127 is a very common alternator. sedan? could you be in Sudan?
Common issue, provided it is not sounding rough when spun is the voltage regulator [ part held by three screw bolts ] Plenty of info on you tube about fixing alternators

mystery · Oct 30, 2023

unless the charge warning light is wired correctly the alternator will not charge

the-prince-e-paul · Oct 30, 2023

Not having a great day! I'm in 'Sweden'.
As for the wiring set up, I've had the Landy since 2008 and despite having changed the alternator for this new one around 12 years ago, I've not altered any wiring. I'm wondering if there could be a break in the wiring. If so, is it simple to run a new wire from the alternator, if so, does a yone know where it is wired too on these?

I had a bit of moment and took out the alternator to have a look at it (inside). In doing so I removed the regulator and broke off one of the brushes so will now need to change the regulator, at the least. That said I don't know what is going wrong if the alternator is fine. I know these can be sourced for £60 new so not an expensive part really.

Thanks for the advice.

mystery · Oct 31, 2023

jimleshed · Oct 31, 2023

Physically, the wiring runs under the Thermostat housing, along the block under the glowplugs etc, then into cabin via a big multiway connector. On mine the wires into/outof this connector had a tendency to break. From memory its an 8 way connector, only 3 wires on mine actually still go through it! The rest are properly bypassing it with nice soldered connectors.

the-prince-e-paul · Oct 31, 2023

So if an getting this right, only one thin wire from the alternator needs to link up from the yellow/ green connector spade on the alternator to the connector block that feeds the dashboard warning light. Sorry I'm asking what might seem like obvious questions but I am going to give it a go at retrofitting a new wire. That should at least give me a live feed to the light, and tell me if the circuit is working.

tottot · Oct 31, 2023

Yes that's the one, Light may well work with new alternator.

the-prince-e-paul · Oct 31, 2023

I checked took the dash panel front off and fed a positive wire to the circuit and the alternator / battery light does come on.

I've decided to go with a replacement so will see in a few weeks if it does fix the problem. I seek to recall for a while that the battery was only charging at around 13.0-13.5v when it did actually charge. Not sure if that is normal range for one of these old Lucas 45a A127 units.

tottot · Oct 31, 2023

When a battery is getting fully charged you will see the voltage delivered drop off to prevent over charging. This is what the regulator does. 13.5 is not bad. Regulator and/or brush/commutator fail is the usual issue.

the-prince-e-paul · Nov 2, 2023

As an update I've checked the alternator light by shorting the third wire on connector block and the dash light works fine. I had a look at the alternator and one of the connections on the rectifier looks a bit charred. With that and the regulator bushes being knackered I'm definately going to replace the alternator. Can anyone recommend a best option. The original is actually a Lucas A115 45A. I'm not running anything other than a radio, but do have a split charge system with leisure battery for when camping.

I've seen Lucas A127 for the newer 200tdi etc. Mine is a 2.5na 1985 ex-military.

I'm on a budget and have seen alternators at £65 and upwards.

Any recommendations appreciated.

Paul
Småland, Sweden.

tottot · Nov 2, 2023

As noted before the Lucas 127 is a wildly used unit, the main difference is pully size/type.
I have a 115 I keep as spare for a number of vehicles.
A alternator for NA, 19j or 200tdi will suit.
I repair my own alternators.

the-prince-e-paul · Nov 2, 2023

I would have had a go but u sure qhays going on with the current one and the charred electrode phases me a bit. Ont final query ive ser mention of left hand and right hand pulley advertised, oddly left and right sides are shown with the same picture. From this picture can anyone clarify. Looking at most of the ones advertised mine would seem to be a right hand fitting, however I have seen somewhere that this model (1985 2.5na) should have left hand fitted.

Alternator connections

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