Voltage problem

[en4239]

i have a '92 ranger 3.0v6 and when its idling the voltage meter goes up and down slightly fluctuating. i can really notice it at night with the headlights on. i can see them and the instrument lights dim and get brighter. when the rpms are above 1,000 the meter stays still. could it be the alternator going bad?
it has a brand new battery so i know thats not the problem.

 

[MAKG]

i have a '92 ranger 3.0v6 and when its idling the voltage meter goes up and down slightly fluctuating. i can really notice it at night with the headlights on. i can see them and the instrument lights dim and get brighter. when the rpms are above 1,000 the meter stays still. could it be the alternator going bad?
it has a brand new battery so i know thats not the problem.

As long as the idle voltage is greater than battery voltage, the charging system is working. You MAY have a blown diode in the rectifier, but it's not at all unusual to get low voltage conditions at idle. The charging system can last for a very long time with one blown diode (two is very often fatal, though).

Measure the idle voltage (with a real voltmeter), and if it's more than about 13V, it's good enough.

 

[calypso93]

My 93 4L alternator has a two plugs going 1nto it. The single wire one got loose a few times and gave the same signs as you describe.

 

[en4239]

My 93 4L alternator has a two plugs going 1nto it. The single wire one got loose a few times and gave the same signs as you describe.

ok ill make sure that they are tight