Gas gauge needle jumps back and forth very rapidly?

Hello,

It sounds like you have an issue with the stepper motor for that gauge.
On these years GM trucks have issues with those little motors that controls the gauges, going bad.
Sometimes the gauges can fluctuate back and forth as you drive or provide no reading at all.
Replacing the motor should fix the issue.
In order to replace any of the stepper motor, you will have to remove the gauge cluster and access it from the back.

I have attached the wiring schematics of the gauge cluster for your reference.

Please let me know of any questions.
Thank you.

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