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sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 22983
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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2007 jeep commander 4.7 flex. Speedometer and tach bounce

Customer Question

2007 jeep commander 4.7 flex. Speedometer and tach bounce while driving. Replaced speed sensor but new cluster in still came problem. When in park the tach moves up and down. Please HELP!
Submitted: 1 year ago.
Category: Jeep
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

I would first suspect the instrument cluster if it's affecting both the tach and speedometer but if it has been replaced with a remanufactured unit and the problem is unchanged then you should be able to rule out the cluster.

I've seen failing alternators induce electrical noise that would cause issues like you're having, especially the speedometer moving on it's own while not moving. Can you try unplugging the alternator field connector when the problem is happening and see if it goes away?

Customer: replied 1 year ago.
No alternator is fine.
Expert:  sprinkles08 replied 1 year ago.

How did you determine that?