today battery light stayed on when i started car so i was too scared to drive it. i checked voltage at battery and on B+ terminal at alternator at idle and it was only 11.5v. after stopping it and starting a few times and battery almost being flat i gave the engine some revs and voltage shot up to normal 14.1v and stayed that way even when i stopped and started engine again.. anyone know why this could happen? also air bag light was flashng and now it stays on

its ef falcon

Last edited by spanky on Wed Jul 14, 2010 3:56 pm, edited 1 time in total.

could be that your alternator is about to die.... airbag should flash a code when you first start.. Could be a low voltage code.....

yeah not worried about air bag light coz it happen when low voltage.
anyway i took alternator apart to check brushes here is a pic can someone tell me if these need replacing

since it's apart I'd replace them anyway. What do the slip rings look like? Do they have massive grooves warn into them? Are they shiny or do they look dark where the brushes are rubbing? Generally if they're not making a good contact then you'll see a bit of carbon build up on the slip ring and it will look a little darker, this will help you diagnose whether it's got a sticky brush or something too. The fact that it started charging when you gave it a good rev indicates to me that it possibly wouldn't self excite so perhaps a new reg could be in order. Since it's out and apart, I'd give the whole thing a good check (stator, diodes etc) and replace the replacables (including bearings).

Last edited by presto on Thu Jul 15, 2010 4:09 pm, edited 2 times in total.

when u say light stayed on did u give the car a rev to see if it went away most times ur bushes stick a little a a rev will fix it

well 1 ring was much darker than the other and its brush was more worn...after a clean up both slip rings appear in good nick tho. also im not sure which brushes to get mine are 8mm wide but the mitsubishi ones on ebay are only 6mm.. the bosch ones are 8mm would i be able to use those in a mitsubishi alternator?

http://cgi.ebay.com.au/BOSCH-ALTERNATOR ... 0609325977
http://cgi.ebay.com.au/MITSUBISHI-ALTER ... 0162477162

yeah it takes a few mins to warm up then the revs makes it go away, hopfully new brushes will fix it worth a try anyway

Take the stator / rectifier assembly to an auto elec and get them to check the diodes and stator, probably nothing wrong there but it only takes two minutes and they shouldn't charge you chips for it. Auto elec should have brushes there in stock too, the right ones. Get them to match you up a pair and they should only be 15-20 odd bucks, maybe less I can't remember. That way you know they're the right size, length and have the right taper on the end and a hole in the right spot for holding them back while you put it together. For the sake of a couple of bucks it saves you having to muck around incase they are different at all (spring locator at base of brush, orientation of wire attachment at the base, different length etc etc)

Are there groves warn on the slip rings from the brushes or once you cleaned it up they're completely flat? I assume it's a Falcon, is your power steering leaking at all?

Hi Everyone,

Can someone instruct me on how to change the alternator belt on an ED Falcon? 93 Model?

She's my first baby, and I don't want to do her the indignity of breaking down on the side of the road.

Thanks in advance