hey everyone
the other night i was driving along and went around a corner and then all of a sudden all 3 of these lights (Altenator light antilock light and brake warning light) all came on at once...
the altenator light has been flicking on and off ever since. i have a volt meter in the car and at idle it is 12.8v then at any throttle it spikes to 15+v then settles back on 13.8v
im guessing it is the reg in the altenator but it wouldnt really explain why the other 2 lights came on
anyone had this before?

hey everyone
the other night i was driving along and went around a corner and then all of a sudden all 3 of these lights (Altenator light antilock light and brake warning light) all came on at once...
the altenator light has been flicking on and off ever since. i have a volt meter in the car and at idle it is 12.8v then at any throttle it spikes to 15+v then settles back on 13.8v
im guessing it is the reg in the altenator but it wouldnt really explain why the other 2 lights came on
anyone had this before?

Erratic voltages can produce unusual occurrences in electronic systems. There's quite a bit in cars these days, engine/trans ecu, BEM, Cruise control control unit, ABS computer, so i'd sort the alternator out first if all those came on simultaneously.

Sounds like the regulator to me. Definatly a DIY job

either the brushes have worn out or the the regulator has died. either way a new alt is needed.

If the regulator has died you can replace that without replacing the alternator

you can but why?

might as well get a new one so its all serviced. ie new bearings new brushes and machined slip rings..

either way a new alt is needed.


It would be better to replace the alternator but some people may not be in the position to buy a new alternator and possible pay someone to fit it

Maybe first I'd check the battery connections - remove them, clean, apply some vaseline and replace/tighten them. Then if the problem occurs again, I'd check the reg/brushes as mentioned above. The reg/brushes are held in by 2 screws at the back of the alternator. I've never removed a Magna alternator but I seem to remember that it takes some time. Maybe check the workshop manual or see this link: http://www.aussiemagna.com/forums/showthread.php?t=84402
A new reg/brush set costs under $70 over the counter....a new alternator (Bosch) costs about $300. I'd figure on 2 hours labour to R/R the alt @ $90 an hour = $180. So the difference is quite considerable. ($480 or $70)
There is no guarantee that the problem is the alternator, so I guess that leaves you in a quandry.
If it was me, I'd remove the alt, remove the reg/brushes from alt and decide from inspection whether they are worn etc. If unsure, take the reg/brush set to an autoelec and ask his/her advice.

thank you all for your ideas. would it be possible to replace the reg and bushes with the altenator still in the vehicle?

Have said this many times and here goes again

If you just do the cheap ass option of reg and brushes, you will have the same issue in a short time

When you reco an alt, you need to do a diode test, machine the armature, replace bearings etc etc.

Dont was to upset people but if you can not afford to replace something on a car that is important, take the bus. Owning a car means maintaining that car, if you can not maintain the car you can not afford to have the luxury of having that car. If you thorw money at a reg now, then again in 6 to 12 months time again, you may as well just get an alternator

thank you all for your ideas. would it be possible to replace the reg and bushes with the altenator still in the vehicle?

looks almost possible on mine except I'd question whether the dipstick gives you enough room to move though. You are better off doing the whole job thoroughly, if the brushes/reg are shot most likely other things are not far behind. I have had a $10 bearing seize and cause $100s of dollars damage on another car I had many years ago.

Surely a new alternator assembly is cheap as chips anyway, so why not replace the whole thing?

Primarily being a motorbike rider, I'm amazed how cheap car parts are in comparison!

thank you all for your ideas. would it be possible to replace the reg and bushes with the altenator still in the vehicle?

To the OP....I had a look at my TL, and it seems reasonably easy to perform this operation with the alt still in the car - first I would disconnect the battery, then I'd undo the 2 phillips head screws holding the assembly to the rear of the alternator and ease the reg/brush assembly past the dipstick tube (which should be removeable). Assembly is the reverse with extra care inserting the new assembly due to longer brushes.
However, if you are a bit uneasy about doing this, I'd call by an auto elec and ask if they could fit one for you - the labour would be 15 minutes max and cost should be no more than $40 on top of the cost for the reg/brush assembly. As mentioned before, there is no guarantee that this is the actual cause of your problem, but it does seem the likely cause.
If money was not a consideration and/or you are not a DIY person then either a new unit or a reco unit fitted by an auto elec would be the preferred option....but that's just my opinion.

Have said this many times and here goes again

If you just do the cheap ass option of reg and brushes, you will have the same issue in a short time

When you reco an alt, you need to do a diode test, machine the armature, replace bearings etc etc.

Dont was to upset people but if you can not afford to replace something on a car that is important, take the bus. Owning a car means maintaining that car, if you can not maintain the car you can not afford to have the luxury of having that car. If you thorw money at a reg now, then again in 6 to 12 months time again, you may as well just get an alternator

nice to hear another voice of reason.

you dont put new brushes on a worn slip rings (armature).. as that in itself promotes brush wear and can cause burning on the slip ring and brushes which can take out the alternator all together.

ok i had the exact same problem close to a year ago, being a 3rd year auto elec apprentice i knew what it was (the reg), and i am fully aware of the effect of new brushes on worn slip rings, but having absolutely no money and needing the car to get around (i was in between workshops and doing a non auto elec job at the time) i just went to ashdowns and bought a reg. Sticking my finger in the reg hole i felt the slip rings and there was no significant grooving, so i started the car without the reg in and stuck the emery paper in there and linished the slip rings. Then blew it out with the compressor. No problems, I did that end of march last year and its still going strong.

you do have to remove the dipstick tube (one bolt...which can be a pain to line back up but not too bad) and then the reg is obviously just 2 screws and the plug and its out. had i of been in a workshop at the time i would have pulled it off and reco'd it properly but i wasnt. Having said that its been perfectly fine since i put the new reg in, sure, it will prob run out of brushes sooner, but hey, by the time it does that, it will be someone elses problem.

As for the warning lights, the alternator light comes on because of the fault, the abs light comes on because its sensing overvoltage and the brake warning light comes on because the abs is faulting.

But yes, you should have the alternator reco'd or exchanged.

ok i had the exact same problem close to a year ago, being a 3rd year auto elec apprentice i knew what it was (the reg), and i am fully aware of the effect of new brushes on worn slip rings, but having absolutely no money and needing the car to get around (i was in between workshops and doing a non auto elec job at the time) i just went to ashdowns and bought a reg. Sticking my finger in the reg hole i felt the slip rings and there was no significant grooving, so i started the car without the reg in and stuck the emery paper in there and linished the slip rings. Then blew it out with the compressor. No problems, I did that end of march last year and its still going strong.

you do have to remove the dipstick tube (one bolt...which can be a pain to line back up but not too bad) and then the reg is obviously just 2 screws and the plug and its out. had i of been in a workshop at the time i would have pulled it off and reco'd it properly but i wasnt. Having said that its been perfectly fine since i put the new reg in, sure, it will prob run out of brushes sooner, but hey, by the time it does that, it will be someone elses problem.

As for the warning lights, the alternator light comes on because of the fault, the abs light comes on because its sensing overvoltage and the brake warning light comes on because the abs is faulting.

But yes, you should have the alternator reco'd or exchanged.


Handy to know, but are you suggesting to place your finger with some emery paper in a confined hole and have the alternator spin at probably 2-3 times the engine speed ? Sounds a little risky?

Just for a guide what's the Reg worth retail, and how many Ks had the Alternator done?

If the OP does go for a reco/overhauled alternator, they should ask exactly what they are buying. Many so called reco/overhauled units are simply repaired and then sprayed silver and a sticker attached. They should also carry a guarantee identical to a brand new unit and include labour costs should the unit fail. I'd expect the slip rings to have been skimmed, new reg/brush set fitted (not just new brushes) and new front/rear bearings. Units that are simply cleaned/inspected means little.
Ebay have reco ones from $110 to brand new at $280....surprisingly the reco ones have 12 months warranty.
Good Luck.

I like the idea of simple and free repairs. Which isn't to say I avoid spending money. I just rather fully diagnose the problem as best I can first up to avoid spending money unnecessarily.

This means doing all the simple, and free, things first - clean/check battery terminals and electrical connections. Have the battery fully tested properly first - a lot of battery places will do this for free. Check/clean/replace any suspect fuses. And check the alternator belt tension and belt condition.

After all of this, and its still weirding out on you - then you look at replacing or reconditioning the alternator.