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Possible Alternator failure, diagnostic help required please
m4maverick - 17/6/12 at 05:28 PM

Hi all,
I was wondering if anyone can confirm or have any other bright ideas as I have reached a dead end but don't want to spend money on a new alternator without being sure I need it.

This is a Lucas LRA101 on a 2.0l Silvertop Zetec in an Avon. This is a completed vehicle and has been fine in the past no problem, just happened a couple of days ago.

My ignition light does not come on and the alternator is not charging.
I have checked the following;
Bulb is ok
Getting 12V to the small wire at the alternator end
If I earth the small wire at the alternator end the ignition light illuminates
The main wire (thicker wire) is connected to the battery (checked with meter at the alternator end)
Difficult to reach but the connection to the spades in the alternator seems ok, will have the nose of during the week to see properly.

Is the alternator knackered of is there anything else I should checking ? have searched the forum and it seems to point to the alternator but thought I would ask anyway.

Thanks in advance, sorry to those who use multiple forums you might see this posted elsewhere also, multiple views might throw up an option.

Mike W


britishtrident - 17/6/12 at 05:39 PM

The alternator type is usually known as Lucas ACR 17 , not the most robust units but fairly easy and cheap to overhaul once out car the symptoms are not that common but to my mind point to an alternator regulator failure. The regulator is a bolt on part and very cheap, I would be tempted to try a new regulator and brushes you will find both on ebay.


rusty nuts - 17/6/12 at 06:00 PM

Check the charging rate by using a multimeter set on 20v DC across the battery terminals with the engine running, it should read approx 13.5v to 14.5 v if not then it's the alternator. Is it mounted anywhere near the exhaust manifold? they don't like heat so a heatshield may help? It did with my car


m4maverick - 18/6/12 at 06:52 PM

Thanks guys,

Will look out brushes and regulator and see the value equation on replacing these or an Part Ex which is about £36 locally


Thanks
Mike W