Alternator Freakout

[smithoman]

The three lights on the dash are lit telling me that my alternator isn't working. But then the lights will go off and it is aparently working again. Off, on, off, on.....This has gone on for a month. And now, it appears that it is indeed finally dead. But I have never seen an alternator do anything like this before. Usually they die and that's it! Any ideas on whether this is the alternator or not? I check the battery connections and made sure all of that is clean.

I'm worried that I'll buy an expensive alternator and then have some ground problem or something. Any advice out there??

 

[ultrabongo]

1) Sounds like brushes to me. I havent seen this on a toyo but on other vehicles, when the brushes go, it will act like this.
First, dont believe the dash lights. Put a voltmeter on the battery with engine running- you should have at least 13.2 volts, if so, alternator is charging.
Second, check continuity on generator circuit with an ohmeter or test light-
disconnect battery cables first
use wiring diagram to follow circuit and test for breaks, check all grounds for good contact- put one ohmeter terminal on ground point, the other on clean part of frame and you should have continuity.
If circuit checks out OK, and you still have problems-pull alternator, and check brushes for wear. Good luck.

 

[fourwd1]

The on and off thing is typical of the brushes wearing out.

And DO believe the dash lights, Toyota purposely designed it to light the CHARGE/ALT, BRAKE, and TRANS TEMP lights when the alt is bad. It really gets your attention.

Don't necessarily believe the dash voltmeter, it's not real accurate.


But make sure you have cleaned and tightened all batt cables (Pos and Neg) before replacing the alt.

 

[smithoman]

T hanks alot u guys! I agree that the brush are probably going bad. I haven't looked into replacing them but I may give it a try. If successful, I will let you all know.