Guy\'s can someone tell me how to test if my alternator is working.. I have an issue wth my battery light coming on. (explained in another thread)
http://www.mazdarotaryclub.com/forums/showthread.php?t=62220
Am I correct in thinking if I connect a mutlimeter to any live feed and measure the voltage when the engine is running if I am getting 13.5V or more I am getting a charge okay?
Now if I do not then I want to check if charge is leaving the alternator as this is one I have jst swapped over!
So what do I need to measure from to check it properly? There is the main live wire and a two pin lug to choose from. Can I run the car with the plug off to measure from the pins if need be?
Thank you
Lee
connect you multi meter to your battery and check what you got to start with (12.7v ish), then start the car and check again (alternator is now running 14v ish), then wazz all your fans, heaters, wipers,lights, etc on and see what the voltage is should still be quite high (13.5v+)
if there are still concerns after those tests, there is a guide in the mitchell full factory service manual using a ohmmeter with the unit off the car.
Thanks guy\'s.. testing the unit off the car??!
Okay.. I\'ll have a look in my manual.. So there is no on car test?to see if power is coming out of it then? As in directly at the alternator..
Cheers
Lee
not what i meant! follow garys instructions first, that will give you a pretty good idea if the alternator is duff.
but if the problem is intermittent or wildly swinging voltages etc it might be the coils or brushes on the way out, you\'ll then have to test the resistance as per the manual and or disassemble the unit and replace the brushes.
If you get as far as fitting new brushes don\'t forget to clean the \'com\' segments (just gently rub a screw driver or fine hacksaw blade inbetween the copper) and bed the new brushes in by fitting them and honing them to the radius of the \'com\' with a bit of polishing tape.
I have just got a voltmeter its by gunson. id love to be able to use it for checking more than resistance. ill google it at lunch, so many dial settings. i wish i understood them
I use a Fluke! but got this when i was out on the tools fixing machines!:Tongue1
Hi Gary, it may just be a case of a dudd battery? Here\'s hoping! My battery has gone dead again after only a couple of days which included a 4 mile drive of which 3 miles I had the Alternator light on? I am guessing that should not kill the battery so quick? Anyway. Is the failure in the alternator the brushes then? the one I took off everything seems fine inside.. The diodes or whatever the little canisters at the back connected into the windings are all looked fine. Not sure if they fail and leak like a capacitor?
What is the \'com\'? Please confirm..
Is there anything on the shaft side/core of the alternator that can result in it failing as I only had a back plate part to swap over complete with the outer windings? I hav another core but a fin needs straightening out so it spins freely in the housing.
I should get a battery and fit it Thursday with luck then can do some voltage tests. Does anyone know if a low voltage would cause the ABS light to go on? Also what is the reason the oil and water warning lights come on with the alternator light for?
Thank you
Lee
when my alt died last and it was running low voltage (it might be that your battery wont take any more charge) all the lights on my dash were on... have you tried charging your battery? is it a fluid type battery? if so does it have fluid in it?
I think the battery is a sealed unit.. I will check. It appears to take at least some charge.. but I would need to physically charge it to see how much.. I did notice that the green Indicator cell in it that is supposed to glow when it\'s charged doesn\'t glow green anymore.. Even after a lot of charging! Not sure how reliable those indicators are though?
Thanks
Lee
Just to confirm. I last charged the battery last week.. fitted it on Thursday night.. car sat until Sunday.. Then I went for a 4 mile drive in the evening.. lights and fan on.. Warning lights all came on about 1 mile into the drive.. Then car sat again until today.. Went to fire it up this evening and battery is all but dead.. Measured 9 volts with my meter.
Lee
i would say its dead then mate, the indicators seem pretty accurate to me, go buy a new one and slap it in, or borrow one from another car and give it a try!
so what your saying is with a fully charged battery (3-4 days prior) you can start the car from cold and run for about 4 miles and the alternator/battery charge light is on for 3 of them! (sounds like alternator is not charging the battery to me)
start again dude and test in this order-
1:- charge battery up again and test voltage=
2:- connect battery and check voltage (at battery terminals)=
3:- start car and check voltage (at battery terminals)=
4:- Turn all your gubbins on heaters,lights etc and check voltage (yep you guessed it)=
1= voltage should be at least 12.5-13v
2=very similar to (1) dependant on alarm expect a little drop.
3=should be 14+v ish
4= should be slightly less than (3) if this is down to or less than (1) then your alternator is knack\'d, you could fit new brushes, clean comutator (contacts brushes rub) and meter out rotor windings (should be balanced) (set meter to ohms)
or take it to an auto electrician who will do the above test in 5mins and may do a drop test on the battery too for a few quid!
I got a good battery sorted today. So I aim to fit and test it tomorrow. Aside the checks at the battery suggested above I have read the manual about testing the alternator and it gives you the expected voltages at each terminal when the car is at idle.. Only thing I don\'t get is it says you cannot earth the main terminal \'B\' on the alternator or the \'L\' terminal which goes to the warning lamp when the engine is running? How on earth do I test them with my voltmeter then? It also says you cannot run the car with the plug going to L and S disconnected!
Any advice please so I don\'t blow anything up that isn\'t already blown!
Cheers
Lee
Okay guy\'s any more help with the above about testing the alternator?
I connected up the battery which showed 12.25volts on it\'s own. When I started the car at idle all my warning lights stayed on! Doh! I checked voltage at the battery and this was down to 11.6v. I do have an oversize pulley kit fitted FYI.. but from what I understand the voltage should have gone up?
I turned on the lights and fan and it drop to just under 11.3v.
Reading the manual I cannot take voltage from any points with the car running as I cannot earth B or S? so I couldn\'t test directly to see if I was getting output from the alternator. But I did turn off and check for continuity between S and B to the battery whch seems fine. The only bit I could check was the alternator warning light wire L as I am not sure how to do that?
Please let me know thguhts on voltage. I will get someone to come and rev it tomorrow to see if that gives a voltage increase if that helps solve anything? No one around to hep me tonight!
Also I disconnected the battery again and measured the voltage at just over 12v after it had been running?
Cheers
Lee
sounds like alternator or wires to it to me?
As above dude, battery sounds o.k but that test is showing that for whatever reason the alternator is not putting any charge to it. Check connections at the alternator and battery are o.k, then possibly bite the bullit and order up an alternator!
I used you tube to find out how to use my multi meter, and check the alternator/ battery short circuits etc. theres some mad videos on there of some crazy mechanics. All there in video for you to search. learnt alot last night.
Quote from: DR SCHNITZEL;668638I used you tube to find out how to use my multi meter, and check the alternator/ battery short circuits etc. theres some mad videos on there of some crazy mechanics. All there in video for you to search. learnt alot last night.
And theres me and the misses wasting our time all those years ago doing an apprenticeship!:Giggle
I wish i knew about You-Tube 18 years ago (god that makes me sound so old):Grrr
Okay guy\'s,
I am guess the fact that I have continuity from the alternator to the battery positive terminal on S and B means the wiring is okay? The only wiring I couldn\'t check is the \'L\' terminal to the warning light but I guess that has no impact on if the alternator is charging or not.. So drawing the same conclusoin that the alternator is dudd.. As it seemed to be okay to start with a charged battery I want to know that there is nothing that could be damaged in my wiring causing the alternator to blow? i.e Does the warning light only come on if the alternator is putting no voltage out or if there is sufficient charge in a full battery would that keep the light off for a while?
I don\'t want to put a third alternator on a blow that was well!
Thank you
Lee
Please can someone confirm if I can start the car with the plug off the alternator or remove the plug once the car is started without damaging anything? The manual implies not but in gather I need to to check if the fault is in the alternator or wiring.. i.e if the light goes out when the plug is off then it\'s the alternator for sure.
Thank you
Lee
Quote from: gary dickens;668643And theres me and the misses wasting our time all those years ago doing an apprenticeship!:Giggle
I wish i knew about You-Tube 18 years ago (god that makes me sound so old):Grrr
I should be a fully trained auto electrician by this time next week ;)
Quote from: DR SCHNITZEL;668668I should be a fully trained auto electrician by this time next week ;)
Hahahaha!!:Thumbs-up
I\'m pretty sure you\'ve got a faulty alternator. Running one without the battery as ballast (yanking the terminal when you couldn\'t get her to stop) tends to kill them. I do have a couple of spares which you\'re welcome to try to confirm though.
Thanks Ian,
I am sending mine in for a repair quote tomorrow.. Pending that I might be interested in buying one off you if you want to sell one?
Cheers
Lee
No problem. Just let me know.
Ian, Can you let me know cost for one good delivered alternator to me please!? Also is it something you can ship straight out so I can get it prior to the weekend?
Cheers
Lee
£30 if you want to come and pick it up? Havant isn\'t far from Basingstoke if you\'ve got another car to make the trip up one evening? Otherwise, £15.50 express48, or £20.50 for express24.
Thanks Ian, I already have one on the way now. If I get stuck though i\'ll come back to you.
Cheers
Lee
Did replacing the alternator fix the fault mate as mine has the exact same syptoms as yours and would be handy to know if you sorted it
Sure Did mate.. All the lights went out as well.
Now I have flooded the motor this morning and cannot get it to start at all! Great! If it\'s not one thing it\'s another!
Lee
Cheers dude wherebouts did you get the alternator and is it easy to replace?
Hi There, Got one from a breaking thread on here. Ebay is another option or there are a couple of breakers about yo coud try. I am sure if you put a wanted out you\'ll get an answer.
Easy enough to change.. Just take the intercooler hoses out of the way and undo the bolts to release the belt tension. remove the plug and main wire. (disconnect battery first). Then take the main pivot bolt out and the tension bolt and you should be able to wriggle the alternator out from under the bracket. i.e leave the bracket bolted in place. Its a bit of a squeeze past the little water pipe by the main pivot bolt but it goes. I did mine in and out in under 30mins.
Good luck,
Lee