Overcharging Alternator?

So yesterday I was driving back from a fishing trip with the a/c, lights and radio all on.

Suddenly after I turned on the headlamps I get a red message on the dash: "CHECK GAUGES".

Sure enough, my electrical gauge is pegged on the max! I noticed when turning on dome lights they flickered, and signalling made them flicker, too.

Does this indicate I have a bad alternator? Voltage regulator? If I do need one, what's the best to buy and what voltage? Everything else on the jeep has been running excellent!

Tried to search this subject but instead got all results for alternators not charging, as opposed to OVERcharging...

Any help would be very well appreciated.

Thanks in advance.

Could mean a bad regulator, but my first suspicion goes to a bad battery.

Bad battery connection probably - the electrical system needs the battery as part of the regulation circuit, the regulator isn't designed to handle such a small load as running without a battery.

Failing that, I know some of the gauges will peg due to error conditions, not because they're actually reading valid data - check engine light? pull codes?

Battery is an Intersate less than 1 year old... with a little corrosion on one terminal. Maybe it just needs to be cleaned??

Local mechanic looked it over, but found nothing; instead just told me to drive it around and see if the problem occurs again!

Did it stop having the problem then? How long did it do this, and did you notice it doing anything different after it stopped?

Guage was pegged? Hi, or Low? Either way, it could be the regulator, but of course, check the following.
Clean batt terminals
Good connection at the alt and where the cable connects at the solenoid or PDC.

Use a voltmeter to check the VDC at the terminals off and running. 12.4 off, 13.4+ running. If over 15+, bad regulator.

Voltmeters are your friend. They pay for themselves the first sensor or relay that checks ok and doesn't get replaced for no good reason . . .

TiRod said:

Guage was pegged? Hi, or Low?

Click to expand...

Guage was pegged on the high side. I turned it off when it happened, waited about 20 mins, then cranked again and it kinda struggled to catch and start. Almost as if needed more juice...

Since then, this problem has not happened again.

I will check all connections, thank you.

Check the voltage of the battery not connected to anything, then check it again with the cables connected, vehicle off, then again with the vehicle running, and again at the alternator with the battery connected. If you have access to an amp meter or can stop by a shop that has one, check the amps off the alt to the battery.
Report back with your findings.

What year?