Number one might be a regulator failure, brushed, diode meltdown open stator winding.

two and three sure sound like regulator failures to me.

Two thoughts:

1: If the manufacture did perform a perfornace wind and it just happens that a fresh factory unit puts out a bit more than the name plate, odds are the manf is usning low grade aprts on the rebuilds, especially the regulators.

2: If the units are being wound for more output and they are failing what could cause that?

One reason would still be cheap regulators.

Another would be the current draw on the stator (rotating section that generates the demand variable magnetic field was wound to increase its current (or substituted for a another , has a short etc). That increased current causes the regulators oputput transistors to fail.

It never hurts to check the vehicles wiring. A loose connector at the alternators output wire casues whats know as a field dump. The alternator is putting out say 40 amps and it gets momentarily disconnected, with no load the output voltage tries to shoot up. There are / should be Zener diodes in the output circuit to snub the voltage down and prevent the spike from failing the switching diodes, however the Zeners can only handle so much and over time this can fial them.

Once they fail the main diodes would see the full voltage spike and fail as well. So check your fusable link and all battery / alternator connections on the heavy wire from the alternator.


There are two other connections to the alternator:

Connection #2, Sense wire

Make sure the sense wire to the battery is properly connected and not intermitant. Again if the sense wire opens up the regultor thinks the battery is low and tries to put out its maximum output. A bad connection there would cause charging problems.

Third connection:

Also the switched voltage needs to be working properly. There are several diodes in the dash that connect warning lights to the sense wire. The diodes prevnt a back feed of voltage once the vehicle is running. If one was shorted sure what I'm not sure what would happen. The EGR, brake and charge light all tie into the switched voltage.

Those bulbs provide a small ammount of current to get the alternators field so it starts charging when it first starts spinning.

No connection there or low current causes no output till you first rev the engine and get the alternator to self exite.

Make sure the brake bulb and charge bulb is lit when you turn the key to the run position but before the motor is started.

Or it could just be crappy alternators <img src="/forums/images/graemlins/cyclops.gif" alt="" />

Kevin