oem voltage gauge drops w/ warmup?

Amongst other things, I'm a simpleton when it come to electronics. I was curious if anyone knew why the the voltage drops a little as the car warms up. On start the gauge is at 14v and then drops to about 12v at operating temp. What am I missing, or is it a Jeep thing. 89xj 4.0 auto 200k

How old is the fan belt, the expand some when warmed up so it might be slipping. Pickup a krikit II belt tension gauge from a NAPA store and check it's tension, should be around 70LBS with a used belt, 80-90lbs with a new one.

Voltage

JGXJ said:

Amongst other things, I'm a simpleton when it come to electronics. I was curious if anyone knew why the the voltage drops a little as the car warms up. On start the gauge is at 14v and then drops to about 12v at operating temp. What am I missing, or is it a Jeep thing. 89xj 4.0 auto 200k

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ITS STARTING AT 14 VOLTS BECAUSE YOU'VE USED VOLTAGE STARTING THE VEHICLE GOES TO 12 AS YOU DRIVE IT'S RELPACING THE VOLTAGE VIA THE REGULATOR

the basics of 87-91 renix systems Xjs is this- the guage lies.
what your seeing on the guage is downstram voltage- its whats available inboard, and not underhood. your true voltage will be at the battery, or the alternator-

try this- drive down the road, turn every thing on, and look at the voltage- if it were the true voltage, your battery would be dead quite soon, yes? Anything under 12 is gonna drain that battery. They way they wiried it, the guage is downline of everything that uses voltage- it should have been exactly opposite, but nooooo.

There was a site somewhere that showed how and where to cut a wire trace on the back of the speedometer so it would show true voltage, but with all that work, you could just as easily put in a aftermarket guage setup.

re-test yours at the battery post- set your mind at ease.

another thing could be your battery cables getting hot, which reduces the amount of juice that can flow through.

As RichP mentioned, check your belt tension.

(Rich, I'm not familiar with the tension for the 89s -- can you confirm the values you posted)