Ok, the deal with my alternator:It was beginning to go bad, but I thought it was my battery, (which died, of course since the alt. wouldn't charge it anymore) so I got myself a Optima Redtop, it worked great for a few days then the SAFS started showing the voltages dropping to below 11 volts and I figured I’ll replace the alt. So I got another alt. I had lying around, got a new Redtop (exchanged for the one that was drained at PepBoys), and everything seemed fine, the SAFC would read 14.3 volts after I started the car and revv it a few times and let it idle.
Recently, this is what’s' happening: I turn on the car, voltage shown is 12.2.After I drive for a while, it starts going up and down with the revvs, so at 5k rpm (without the lights or any other accessories turned on) SAFC shows 15.9 volts, the dash goes very bright, and at idle it's about 14.2.
The thing is that if I apply my brake, turn the lights on, and am stopped at a light, the dash will dim so that it's WAY too dim and I when I apply brakes the volts will drop to 13.5 and keep going down, and the headlights will dim a little.
I don't understand much about alternators, but I don't think they are supposed to put out more than 14 volts and that it should do that constantly, and no dimming or brightening of the dash/headlights should occur. Is my new (old) alternator also broken? It won't put out 13+ volts until I revv the car past3k, and then I have to drive for a while to make it keep it up there.
Is there a voltage regulator somewhere on the car? It seems something is off. My idle sometimes stays at 1500rpm in neutral and sometimes drops below 700...
Any input is welcome,
sil80
alternator trouble
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sil80drifter
- Posts: 1313
- Joined: Sun Aug 18, 2002 5:53 am
- Car: 1990 240SX Hatch
Hmm well the thing is that my afc registers 14.2v at startup but as soon as the car is started, it holds between 13.8 to 14.0, unless I'm at a light and my brake lights are on, then it reads 12.8v. The fact that your system is registering over 14.4v is abnormal. You may want to have your alternator checked out. If that's fine, I dunno what to say as I know there's a voltage regulation system for the 240's but as I don't have my fsm with me it'll have to wait till thursday evening or friday earliest for me to even have a look as to where it might be. If you want stability from your batter or alternator, you can try adding a capacitor to the system, that should keep the fluctuations at a minimum, but it should be a big cap.
as for your alternator and battery problems, I feel you there. When I ordered my redtop optima, my alternator was dying on me and also its belt was slipping too cuz of the coolant that was leaking from the pump which I didn't see at first. But at the time I had just changed my battery so I thought it was that. When that died, I said it's gotta be the alternator. So when my alternator was changed, I found out that my water pump was leaking via a drop of coolant in my eye (hurt like nothing else you've felt before). Needless to say it was an expensive learning experience for me.
as for your alternator and battery problems, I feel you there. When I ordered my redtop optima, my alternator was dying on me and also its belt was slipping too cuz of the coolant that was leaking from the pump which I didn't see at first. But at the time I had just changed my battery so I thought it was that. When that died, I said it's gotta be the alternator. So when my alternator was changed, I found out that my water pump was leaking via a drop of coolant in my eye (hurt like nothing else you've felt before). Needless to say it was an expensive learning experience for me.
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sil80drifter
- Posts: 1313
- Joined: Sun Aug 18, 2002 5:53 am
- Car: 1990 240SX Hatch
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sil80drifter
- Posts: 1313
- Joined: Sun Aug 18, 2002 5:53 am
- Car: 1990 240SX Hatch