Re: What can cause an alternator to go bad?
Lots of good suggestions given. Be sure the battery cable connections, at both ends , are clean and in good condition, no broken strands.
We should know what set up your car has, is it stock OE charging system or has the external regulated alternator been replaced with an internal regulated alternator?
Looking at the alternator rear side, there will three wires, one large red wire to BAT terminal and teo other wires in a connector If the wire connector has the connection like so: II , then it is an external regulated charging system. If the connecctor looks like this: -- , then it is an internal regulated charging system.
All charging system voltage checks should be done at the battery posts with the engine running at appproximately 1500 rpm. On an external, with lights on, heater on, radio on, charging voltage should not be below 13.5 volts. If you have an internally regulated alternator, charging voltage should not go below 14 volts.
As a quick check, measure the voltage from the BAT terminal on the alternator to the positive battery post. This measurement should be less than 0.4 volts. If it is higher, then you have corrosion or a broken wire from the BAt term to the pos post.
The red wire goes from the alt to the horn relay buss bar (drvr side of rad support under the washer fluid bottle). the other connection of the buss bar a red wire across the rad support to a junction block next to the battery, then to a pigtail to the pos battery cable. Any point along this path can be corroded. Remove the connections and clean them with a wire brush. Repair those connections not of good repair.
If you still find charging voltage low, you may want to replace the external regulator with a Wells unit, P/N VR715, an electronic external regulator. The old mechanical ones can get a bit cranky and pitted points inside.
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