Mechanics

I HAVE A WITH AN ALTERNATOR ISSUE... ABOUT TWO WEEKS AGO WITH NO WARNING THE BATTERY LIGHT CAME ON. I REPLACED THE ALT WITH A NEW (WILSON) ONE, NO CHANGE!!! MY QUESTION IS, IS IT AN OUT OF BOX DEAD ORIS THERE SOMETHING ELSE THATI SHOULD BE LOOKIN

2001 BMW X5 • 310 miles

I have a 2001 X5 with an alternator issue. About two weeks ago with no warning the Battery light came on. I replaced the alt with a new (Wilson) one, no change! My question is, is it an out of box dead or is there something else that I should be looking at? Kelly
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Kelly_Fellner
December 4, 2011.



The generator, (alternator), is just one part of the charging system. Your mechanic should have performed some voltage tests first to rule out any other possibility. All generators will have a wire to turn it on when the ignition switch is turned on or when the engine is running. A break in that wire will stop the system from working. A break in the wire between the generator's output terminal and the battery will prevent it from recharging the battery but that usually won't cause the warning light to turn on. There is usually a very large fuse in the under-hood fuse box for that circuit. There may also be a fuse for a circuit for the voltage regulator to monitor system voltage. If that one is blown, the voltage regulator won't turn on.

Caradiodoc
Dec 4, 2011.
All the fuses check out as and the plug for the alternator has power as well Thanks Kelly

Tiny
Kelly_Fellner
Dec 4, 2011.
If you have an inexpensive digital voltmeter, measure the battery voltage while the engine is running. It must be between 13.75 and 14.75 volts. I suspect it will be low since the warning light is on. I suppose the new generator could be defective but that doesn't happen real often. The voltage regulator is built into it so everything is in one unit. If all of the voltages are correct on the wires feeding the generator, it's time to try another one.

Caradiodoc
Dec 4, 2011.