Alternator19

My volts have been jumping up to 19 lately while driving, the check gauge light comes on, and then it will go back down to 14 for a few miles before jumping right back up again. I changed my alternator about 2 months ago, and it fixed the problem, but now it is doing it again.(Its a 1997, and I know it is regulated by the computer). I am not sure if I can just keep driving it like that? It's my only vehicle right now and I kind of need to drive it. Any solutions? Should I keep driving it?
:wstupid:

your gona do damage to the battery eventually try another battery and make sure its not shorting out or something. might be the computer fing up or something too

Make sure the battery isn't shorting out? Could my problem be the battery? I figured it was the computer fing up, but I do want to replace the whole computer. Any more suggestions? Thanks dzraces

How sure are you that it's really the alternator and the battery voltage, and not the gauge cluster at fault? Could a bad ground in the gauge cluster cause this? I suspect it could, especially since this vintage of Jeep is noted for having problems with the gauge cluster connectors. Before going ahead, I'd try running a voltmeter from the battery itself. How about other symptoms? Bad running, bright lights, radio issues? If nothing is happening but the gauge reading, suspect the gauges.

Everything is working perfectly, the guage just intermittently goes from 14-19. I changed the alternator originally, and it went away, 2 months later and it is back. I will try to run a voltmeter tommorrow, I don't mind driving it like this, i was planning on wheeling this weekend and don't want to get stuck in the middle of no where. Thanks for the input.

It can be dirty faulty connections on the alternator, that could explain why replacing in temporally fixed it.

langer1 said:

It can be dirty faulty connections on the alternator, that could explain why replacing in temporally fixed it.

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Because the external voltage regulator cycles the ground path to the alternator field (field switched off = no output), I would expect faulty connections to result in undervoltage, but it's certainly a good idea to check the wiring harness and connectors for a possible intermittent short or leakage, especially in the ground line to the PCM.

Go to a shop and test it all with a Volt Amp Tester (such as a VAT 40..or newer).
* first load test the battery
* test the alternator for charging
* test for voltage drop at ground cable
* test for voltage drop on positive cable

As you know...the voltage regulator is in the Powertrain Control Module (PCM) in the 97 MY and the charging test with the VAT will comfirm if it is working correctly. The load test will tell if the battery is shorted or not able to support a load.
Also compare the VAT voltage readings with the gage on your dash. The instrument pack connector has been know to go bad or even "fry".