Battery Light On?
By: B20Luda
(From: http://www.preludepower.com/forums/showthread.php?p=834749)

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Is your alternator light on? don't want to buy a $150 plus alternator? if so read on..

READ BEFORE U TAKE IT APART..

TOOLS NEEDED
8mm and 10mm wrench
proper sized phillips screw driver (has to be small in length)
feeler gauge
Brain

First of all not sure how many people know this..u guys might already know, but i didn't see it on the site so i thought i might as well spill the beans..

I your alternator light is on its most likely due to the brushes inside the alternator. If your alternator is really noisy or the pulley has a bunch of play this fix prolly wont fix it for long if at all as u have a bearing prob.

To ck the brushes u must remove them, u DONT have to remove the alternator to do this...just follow these easy steps..

Disconnect the battery and remove the the connector and alternator lead on the alternator. u must also remove the plastic part below the wire (just another 10mm nut) once that's out of the way get an 8mm wrench and remove the shield on the back of the alternator (3 nuts) once that's removed u will need a 10mm wrench or small ratchet to get the other bolts off also 3 of them ( the nuts remove previously actually bolt to these) once those are removed, pull off the backing of the alternator.

Now u have access to the brushes. They are located in the center of the alternator it has a rubber shield that goes over them and there fastened to the back of the alternator with 2 phillips screws.. make sure u use the right screw driver to get these off, they are tight and u don't wanna strip them.. once screws are removed pull the brushes off and u will prolly find that there very worn down, at this point u need to contact your honda dealer and get a new set..most dealers actually carry these and don't ask for brushes for a prelude ask for this part number...31105-PZ1-003 this is a new brush set can be had for about 20 bucks...

now to install these bad boys...take a feeler gauge and lay it over the shaft the brushes ride on and slide them into place, once in place just install parts in the order they were removed...If your brushes were worn out this will usually fix the problem, i have done it on countless customers cars and a few of my own preludes....