1991 240 volvo, water temp guage and fuel guage occasionally fluctuate. For example, the fuel guage will drop from 1/2 full to nearly empty (top of orange zone), then back up to 1/2 full, in a timespan of 5 minutes. In the past, this happened when the alternator or the alternator ground wire was failing. I replaced the ground wire three weeks ago, checked the alternator output voltage with a multimeter, and everything looks normal. What other items could cause the fuel guage and water temp guage to fluctuate?

NOTE: Thanks to LUCID for reminding me that I left off the Model/Year info from an earlier post.

Lucid suggested:
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"Common to both those gauges (and no other) is the tiny 3-pin voltage regulator screw-tab mounted on the back of the panel, right behind those gauges. The VR may be making poor contact, or just going bad.
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Any other comments?

[[ southern fried volvo '91 240 164k mi ]]