Originally Posted by
shogun
Check the battery and the charging voltage of the alternator first:
Find a digital multimeter and stick the probe into the cigarette lighter socket in the center console. Plus into the lighter socket, minus at the side metal/edge of the cigarette lighter. Or if you have a glove box torch socket, put it in there, or directly at the battery posts, whatever is more convenient.
The following are the detail figures I use for my own evaluation:
With key out of ignition switch, should see 12.4V or above. 12.0 V is getting low.
With key inserted and turned to position 2 (don't start car), should see 12.0V or more. 11.6V would be too low.
Crank car, catch the lowest voltage reading during that couple of seconds. Should see 10.0V or above. 9.5V would be marginal.
The above just consider the health of battery itself.
Car running at 1500 RPM or more, should see 13.7 to 14.3V, 13.6V or below means the charging system is weak.