Alt. won't charge under 3000RPM

[l1ttle_d3vil]

I'm having problems with the alternator on my 4age bluetop not charging when the engine is under around 3000rpm. Anything over that and the light goes off. The wiring all seems to be OK so is this likely to be a faulty alternator?

Or if I have a short circuit somewhere in any of my wiring loom is it likely to cause this? (it is a possibility that I have a short circuit somewhere)

If the alternator was stuffed, would it not charge at all - no matter what the revs are at?

cheers.

[fatgtr]

possibly your brushes are knackered

[Fraud]

Without knowing too much about engine electrics, I would think the Alternator would not charge at all if it was stuffed. It almost sounds like a weak connection on the wire relaying back from the alternator to the system?

[Ako]

Tried tightening the belt? Might be slipping but not squealing?

[Punter]

Tried tightening the belt? Might be slipping but not squealing?

x2

I once got a car for $100 because the alternator was stuffed, I tightened the belt and drove it for 6 months then sold it for $500

[l1ttle_d3vil]

sweet will try tightening it, I wondered if it could be slipping but i've never heard it squealing. never though of it not making any noise

[barryogen]

is it a recent thing or has it always done it?

if always, is it being under-driven(as in different pulley than from factory?)?

[l1ttle_d3vil]

no it used to do it ages ago then I tightened up the wire going from the batt to the top of the alternator and it fixed it. then the other day it started doing it again so I played around with that same wire and it was sweet for a day now it won't charge no matter what.

[Malcolm]

not and uncommon problem in Toyota alternators
sometimes it seems to be caused by a dud rectifier diode, causing the alternator to effectively run at a lower output. Sometimes the regulator craps out too, and causes under/over charging (the one in my mr2 charges up to about 16V at the momemt )

basically, you're probably best to get a second hand alt, or get it rebuilt if you want it to last longer (cost will be around $200 IIRC)

[Malcolm]

although juding by the problems you mentioned above, it could be as simple as a bad wire from alt-battery. Have you tried running a new one?

[l1ttle_d3vil]

i tightened the pulley and it didn't fix anything and Ive checked all the wires, they're fine.

I think i'll just find a second hand alternator and try that then

[GOLDAE86]

I think you have a bung regulator in the alternator.Take it out and get to a auto spraky to check it on the bench.

[HELBND]

if youre interested, i have a spare 4age alternator lying round at home you could have cheap