Voltage gauge constantly moving (tried searching)

[Superstar RX7]

I did do a search and I found this to be a common problem, but something I noticed was that in all the threads on where people have this same problem, they also experience dimming of the headlights, dash lights, etc. I don't have this dimming of the lights. My Explorer ('94 Sport) is stock with no electrical modifications or aftermarket amps or speakers, just a Kenwood head unit that I installed 6 years ago. This problem started last week. The gauge will bounce day and night, lights on or off. It happens at steady highway speeds on smooth roads, or just idling in the driveway. I don't think its a ground wire issue because the lights don't flicker or dim when I hit bumps, and it happens when the vehicle is sitting still. The battery terminals are clean and I had put an anit-corrosive on them to prevent them from crusting up. I checked the battery with a multimeter and with the engine off, the battery is 12.24 VDC. Engine running its at 14.5 and the reading on the meter doesn't change.

Is this a sign that the alternator will soon need to be replaced or is the gauge bad?

 

[410Fortune]

if you are getting a constant 14.4 V at the alternator charge wire then your alternator is fine. Test with headlights on, blower on full, stereo on, etc.

Sounds like a ford "gage" issue to me.

 

[Superstar RX7]

Sorry it took a few days to get around to posting to the numbers. I turned on the high beams, radio and the A/C and checked the voltage. It was bouncing between 13.78- 13.92 VDC. I also noticed that the 4x4 and low range lights on the 4x4 switch panel will light up by themselves. Its not bright like when you actually press the button to engage the system and the lights don't come on down under the tachometer, just the round lights on the switch. Not sure if its related to the voltage gauge, but its definately a stange problem. Any insight is appreciated, but if not, then thats ok cause it doesn't smell like any wires are burning and the 4 wheel drive still works when I do press the button.