Charging system questions.

6Stang7 said:

Could my alt. wires be hooked up wrong? Anything else?

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Possibly. It doesn't sound like the alternator field is getting regulated.

6Stang7 said:

My volt gauge (aftermarket) now reads about 15 3/4 while idleing and 16 while driving. What gives? While driving it today it randomly dropped down to 13 for a little bit, then when back up to 16. I have replaced the volt reg in the engine bay. Could my alt. wires be hooked up wrong? Anything else?

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First check the alternator. Here's some preliminary checks:

With engine off, remove battery cable. Make sure all doors are closed; all lighting is off and there is nothing powered in the car (except alarm system and possibly radio memory). Disconnect (+) battery cable. Use multimeter in amps mode to check for any current between the loose end of the battery cable and the (+) terminal of the battery. The current should be tiny, 0.040 amps or less. If greater then there's a chance the alternator has a bad diode. While reading currents greater than 0.040 amps, disconnect the alternator output wire from the alternator. If current drops then the alternator diodes are shot; alternator is bad. Example of this condition: lets say the current reads 1.2 amps with the alternator lead connected; lets also say the current reads 0.040 amps with the alternator lead disconnected. In this example the diode pack inside the alternator has a short. Now if the current is steady and about 0.040 amps in either case, disconnect the alarm fuse. Current should drop. Disconnect the radio memory fuse (or unswitched 12 volts to radio memory). Current should drop to zero. In this example, alternator passes short check. Restore all connections.

With engine running at idle, check the output voltage. Should be 14-15 volts and stable. Increasing rpm should cause it to move up a tiny bit but remain under 15 volts. Decreasing rpm to very low idle may cause the output to drop a small amount but not under 12.6 volts. If it drops below 12.6 volts at idle, check to see what accessories are on (a/c is quite a drag as are headlights in high beam and big stereo power). Turn off accessories and re-check. If this is problematic then consider using a smaller alternator pulley.

If the voltage does not check out the easiest thing to do is to remove the alternator to a tester for bench check (Autozone, etc.)

Newer electronic voltage regulators (aftermarket) don't have relays and points in them to stick and vibrate. Thus the regulation is smoother. Use a good aftermarket electronic (NAPA) in preference to the old style mechanical regulator.

The wire between the F terminal of the regulator and the alternator field connector is critical. The current in this wire determines the output of the alternator. If its high the alternator output voltage is high; if low the alternator output voltage is low. Make sure the wire and connectors are solid.