2.25 Petrol 90 Alternator Questions

Hi All,

Just a couple of questions:-

Q1. The I have 4 wires going to my Lucas alternator:-
2 big thick brown ones which go to the main outputs
1 Thin brown and yellow which goes to the warning light connector
1 Thin brown which is not connected (it's not on my circuit diagram) it does seem to be live 12v!
My Alternator does not seem to have a battery sense connector. I'm just wondering what this thin brown wire is for? Would it go to the battery sense if the alternator had one?

Lastly Q2
Everything is working perfectly in this config, battery being charged and no issues. However!! The battery warning light is always on at varying degrees of brightness depending on rev's. It does seem brighter with more rev's?!?
Any ideas? It's been like this ever since I rescued the car, but not worried about it because I've tested that the battery is definitely being charged.

Thank you!
Paul.

What volts is the alt putting out?
Very few alts are battery sensed direct to the battery these days, most are stand alone units.

lynall said:

What volts is the alt putting out?
Very few alts are battery sensed direct to the battery these days, most are stand alone units.

Click to expand...

Idol with everything off 14.21V
idol with lights on 13.4v
revs + lights 14v
revs with everything off 15v

at idol the battery light is on dim
with revs the battery light is brighter!

Hope that helps? Thanks

84ninety said:

Idol with everything off 14.21V
idol with lights on 13.4v
revs + lights 14v
revs with everything off 15v

at idol the battery light is on dim
with revs the battery light is brighter!

Hope that helps? Thanks

Click to expand...

Sounds to me like something is wrong, basically with ign on there should be 12v to the warning bulb from the ign barrel/live, then as you start engine the alt should send power up the warning light wire which puts the bulb out as there is no longer an earth path, so one end of the circuit must be providing an earth for the bulb to be on.
Of course the circuit could be fine and the alt is at fault, as 15v is pretty high for an older set up.

If its an A127 you can pop the brush box out for a look see, new boxes about 10/15 quid, careful as you refit it to not damage the brushes.

OK Thank you very much. I'll do some more testing with the warning light connector first and see if i can deduce anything further. Thank you for the link, that's really useful.
Any ideas what the spare brown wire is for? Is it for the sense connector (if present)?

I have the same on my 90 with a Disco 1 3.5 V8 non-serp with a Marelli Lucas A127 alternator.
Battery readings are fine but the warning lamp starts to glow as revs increase; only really visible at night.
I changed the rectifier, diodes, regulator and brushes but the lamp still comes on.
https://www.landyzone.co.uk/land-ro...-and-regulator-sorted-it-or-maybe-not.370681/
Next step is to investigate the integrity of the brown-yellow warning lamp at the alt and lamp end.
Good luck @84ninety

cappers said:

I have the same on my 90 with a Disco 1 3.5 V8 non-serp with a Marelli Lucas A127 alternator.
Battery readings are fine but the warning lamp starts to glow as revs increase; only really visible at night.
I changed the rectifier, diodes, regulator and brushes but the lamp still comes on.
https://www.landyzone.co.uk/land-ro...-and-regulator-sorted-it-or-maybe-not.370681/
Next step is to investigate the integrity of the brown-yellow warning lamp at the alt and lamp end.
Good luck @84ninety

Click to expand...

Oh wow! Same problem amazing! This is all really useful stuff thank you......Lots to be getting on with and try. I will report back in due course.
Thank you @cappers and @lynall