Red Battery Light on dash wont go out.

[JONNIGEE]

My red battery light came on my dash a couple of days ago, (Disco 2.5 tdi 95) It started fine until Sunday morning, turned the key all lights came on as normal but no start, left it a mo and tried again and she started. Monday morning started okay, but when I went to go out at dinnertime, nothing, two long sluggy attempts to turn over then click click click click, so I put a brand new battery in and woof she started like a beauty, BUT... the red battery light hasn't gone out!!! Any ideas what it might be??

[Richie_asg1]

Alternator is not charging properly. You can swap the whole thing, or buy a kit to replace the rectifier and all parts that are likely to wear.
Unless it's very old - or has seen a lot of mud, it's usually a rectifier fault.

[Satancom]

Could be a loose cable at the back of the alternator, or the belt may be slipping.

[JONNIGEE]

I've just been to our parts counter to price up a new alternator, and they have three different ones for my year and model disco, anybody got any ideas 65 amp, 100amp?????

[kevinrbeech]

Do you need a new alternator?

I only ask cos if you didn't know that not charging was the reason for the red light, then you may not have noticed if just the belt is broken. It would be a shame to buy a new alternator for £100 if all you need is a belt for a fiver.
Kevin

[ComicalEngineer]

It's probably the alternator dying.

Check the voltage. Without the engine running should be about 12 - 12.5 volts but with the engine running it should be 13-13.5V i.e. about 2V higher.

Sometimes the diode that controls the red light fails but the alternator still charges.

[kevinrbeech]

Sometimes the diode that controls the red light fails but the alternator still charges.

I think possibly the clue was this
Monday morning started okay, but when I went to go out at dinnertime, nothing, two long sluggy attempts to turn over then click click click click, so I put a brand new battery in and woof she started like a beauty, BUT... the red battery light hasn't gone out!!! Any ideas what it might be??

[JONNIGEE]

I've just tested the battery with an alternator analyser, got good readings on battery with engine off, but barely a flicker with engine on and lights on. I've checked the belt and it's not broke or slack, the alternator wheel is spinning like a good un. I've checked the wiring on the back, I have a thick brown wire, firmly connected with a nut, and a smaller thin brown/yellow wire, also firmly connected. However I have noticed there is a small black and white wire hanging from the loom close to the alternator it has a little 'L' shaped black plastic connector plug on its end. I have looked at the alternator but there is no obvious socket to connect this wire to. Does anybody know what this black and white wire is?? I will try to upload a piccy tonight. Are there any other options open to me apart from buying a new alternator.??

[Satancom]

Right you probably have a big cable to the battery, a small cable for the rev counter and a small cable for battrey sensing. If our sensing wire is off then that will be the problem as it will not initiate a charge.

[JONNIGEE]

Ooops sorry forgot to mention in all of this my revcounter doesn't work either!!!!
How do I solve this problem and where does the b&w wire go????

[Richie_asg1]

You may have found the problem - or maybe part of the puzzle.

There should be an alternator plug you can remove and have a look at, to see if any wires are broken. There may be a metal clip holding it in that you need to remove first.

From what I've found Here
it seems the black/white wire goes from the ingnition switch and is directly linked to the battery condition light. Should be a switched live supply to the alternator.

There should be a separate spade connection for that wire. May need a torch and a mirror to see where though. and may be marked D+

Regarding ratings - bigger is usually needed if you run extra lights or equipment. Otherwise stick to normal or replace what is there.
Try to find the fault before replacing it :)

[JONNIGEE]

UPDATE..
Had a good butchers last night with inspection light and telescopic mirror, found a hole in the side wall of the N/S inner wing, it's right beside where my alt sits, and seems to be responsible for showering the alt with water and other such SH1Te. I've removed the Big brown and small wires, cleaned all contacts with WD40 and wire wool and replaced, crossed me fingers and toes, but still no difference, Red battery light still present. Whilst I was noseying I noticed towards the bottom of the alt I've got a small black plastic rectangular box with a couple of numbers printed on, from this a very thin short black wire runs to a hard to spot spade, the connector plug is the same small 'L' shape as the one I have dangling free from the loom. Could this little box and wire be some sort of bypass??? or is it legit? This is really doing my head in I want to crack this problem but I'm losing patience. I'm off to Wales again this weekend and need to sort this bleedin problem. All help and advice very very welcome.
Maybe worth mentioning, about four months ago I had the engine loom replaced as the last one got caught round my prop shaft doing 60 on the M62!! (there are some noises that only LR owners can experience... this was one such occasion!!) It was a second hand loom from a breakers yard, don't know which model/year the donor was, dont know if that would matter.

[Satancom]

If your coming anywhere near swansea I can take a look at it for ya :)

[JONNIGEE]

I'm not venturing that far South unfortunately, bit o fishing at Abergele Pensarn and Rhos then round to Betws, thanks very much for offer really appreciated. Just took a piccy, not very good, and to be honest it doesn't offer much of an obvious solution. It's not the clearest of pictures, but I've tried to detail it as best as I can. If anybody has a similar alternator I'd be grateful of any further advice or a picture.
thanks.