Alternator wiring

Your help is appreciated. I have tried to read every thread on series 3 alternators but can’t seem to find the answer. My old Lucas alternator failed so I ordered the replacement ACR 17. The old alternator only used the 3 pin plug euro set on the rear. The new one has space for an extra connector (see picture) I have had a replacement Lucas wiring loom about 20 years ago bought from Landrover and it has the extra spade connector on it so I have connected it. Right or Wrong? Does any one know where it goes (dash warning light?) it doesn’t appear on the wiring diagram.

Secondly, my brake warning light seems to be on intermittently, could that be the faulty alternator affecting it?

Thanks all.

Does the dash warning bulb work?
Does the alt charge?
Have you checked charging with a multimeter?

What was the extra wire connected to before? Dash warning will be small cable from plug.
Brake warning of low fluid?

tottot said:

What was the extra wire connected to before? Dash warning will be small cable from plug.
Brake warning of low fluid?

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Tottot
Thanks for comming back. The wire wasn’t connected before so jus taped up on the loom. It seemed to work ok with the last alternator. I suppose my concern was that this extra spade might be the battery sensor wire (which I have seen separately on some wiring schematics) but would have thought that would have a colour on it not just brown. The brown with yellow trace (which I assume is the sensor) goes to the main connector.

lynall said:

Does the dash warning bulb work?
Does the alt charge?
Have you checked charging with a multimeter?

Click to expand...

Lynall
Yes dash light comes on with the key then goes off. Slightly irritatingly the new alternator I fitted is faulty and is over charging (up to nearly 18v) so I have another swap at the weekend.

Test your voltage at the battery? This will give a correct reading allowing for losses in the wiring.
The 4th wire you have is likely for something you do not have, a field sensor [ series 3 won't have] so put it back as original.

Captain Cavemen said:

Lynall
Yes dash light comes on with the key then goes off. Slightly irritatingly the new alternator I fitted is faulty and is over charging (up to nearly 18v) so I have another swap at the weekend.

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It does not rain it pours!

tottot said:

Test your voltage at the battery? This will give a correct reading allowing for losses in the wiring.
The 4th wire you have is likely for something you do not have, a field sensor [ series 3 won't have] so put it back as original.

Click to expand...

Thanks Tottot.
I will tape the extra spade out of the way and see how it goes. I’ll be under the car again tomorrow fitting the replacement alternator anyway.

Next job is to find out why the series 3 brake warning light is always on. Everything is working on the brakes but haven’t tested the switch(which I assume is there) on the brake hose split (sorry can’t recal the name of it).

Happy tinkering all.

Dear all,

A note of thanks for your assistance. The new alternator is fitted and putting out a nice steady 14.2v. Sadly the old one had done damage. The main headlights have died. However 2 hours of hunting later I found an inline fuse tucked deep behind the dash on the supply cable and I’m hoping that will solve the lights. The smiths fan that exploded (going to fast on a high voltage) is tomorrows job. Just in case anyone’s interested, I have coloured up my wiring schematic. It’s a shame it doesn’t show inline fuses.

The inline fuses do not show on diagram because it would not have had any, only fuses are under the steering wheel.

tottot said:

The inline fuses do not show on diagram because it would not have had any, only fuses are under the steering wheel.

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It’s interesting. I replaced the much messed about loom about 20 years ago with new Lucas from Landrover and it has a couple of inline fuses on the larger current lines, not installed by me. Melted fuse image below from today.

Captain Cavemen said:

It’s interesting. I replaced the much messed about loom about 20 years ago with new Lucas from Landrover and it has a couple of inline fuses on the larger current lines, not installed by me. Melted fuse image below from today.

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This is the fuse holder the loom came with. https://www.ebay.co.uk/itm/191988870522

Do not know your year, perhaps later models had some.

tottot said:

Do not know your year, perhaps later models had some.

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1980, so a late ish model. You may well be correct. Thanks again.