Battery charging light always on.
 

The charging idiot light on my '93 SC300 stays on after the car has started. Normally, I would assume a bad alternator but I don't have any dimming of headlights or any other electrical equipment even after a half hour of driving. What is happening is that after driving for a while, the engine will stop running altogether. Not fun when you're on a busy interstate. If I wait for an hour and try starting again, the motor will start right up but it will do the same thing again after a half hour or so. The alternator doesn't have many miles on it and I changed it about 3 yrs. ago. I'm leaning towards replacing the alternator since I had similar problems with my LS400. Any suggestions? Thanks.

Have the alternator tested, also make sure the battery ground is making good contact. However, that light always points to a faulty or dead alternator.

alternator
 

I checked the battery voltage with the engine off and it was about 12.4 V.. Checked it again with the engine on and it was 14.5 V. which tells me that the alternator is charging. Swapped battery with one from my other car and the light still stayed on. Sounds like, as you suggested, the alternator is defective. Last time I had an alternator checked at Auto Zone, since it was still under warranty, they said it was good. I brought the alt. to a repair shop and they found defective wiring. Looks like I can still get charging but after things heat up, something shorts out. I guess I'd better replace or have it repaired. Thanks for your help.

My battery light came on intermittently, usually when I was braking, then it progressed to being on constantly. The alternator failure took a few days and I should have changed it out immediately. Instead, I waited until it died on the freeway and I was able to limp it to an exit and had to swap the alternator the next day on the street. Not fun. I say swap it out now before you have a complete failure. Good luck

That sucks man! :( well atleast you knew how to change it out instead of paying!!! I know how it feels to change parts out on the st, my brother, dad and I used to do it all the time! But yes I agree with my man here, change it out before it gets worse!!!

I removed the alternator and brought it to a reliable(?) shop for a check.
Apparently, the alternator is working fine. Re-installed it ( not fun when you're 70 in FL heat). The car started fine but the charging light was still on. Checked the belt and looked for grease on the pulleys. In my shop manual, they suggested the voltage regulator. Since the VR is part of the alternator, could an inspection of the Alt. miss the regulator if it behaved irrationally?

I had the same light on in my 92 sc300 5spd after I took out the interior carpet. The previous owner had aftermarket wiring that was connected to nothing. I ripped those out and my battery light came on and had problems holding an idle. I took out the alternator and replaced it. But the problem was a frayed wire in the alternator connector. I saudered the connection and the light went away.

i have the exact same problem you do. my light used to flicker, now its on all the time.. i noticed last night my headlights wouldnt stay on, and this morning driving to work i noticed higher then usual AFR's.. to me that means my fuel pump isnt receiving the amount of voltage to run it properly.

good thing is, i have a alternator in my front seat and all the tools to put it in.. bad news is, the alternator was used but in good condition, however it doesnt have the nut on the pulley. >.<
got a strap wrench to hold it still, and looks like itll be a little cooler here in MD today. sounds like a good day to work on the car.

That's what I have right now. I've replaced my alternator already so it can't be it. It happens when there's an oil leak, the oil gets to the wires, hot engine boils the oil, oil boils the insulation, then bare wires get contact triggering the battery light.:egads:

i had a fryed/shorting wire that wasnt supposed to be there coming from the coolant tempensor that was squashed under the alternator 14v out.. along time ago i had a crank shaft position sensor wire smashed.