# Eratic dash

**URL:** <https://community.cartalk.com/t/eratic-dash/20242>\
**Category:** Maintenance/Repairs\
**Created:** [October 2, 2008, 1:11am UTC](https://community.cartalk.com/t/eratic-dash/20242 "2008-10-02T01:11:42Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![mainer](https://avatars.discourse-cdn.com/v4/letter/m/96bed5/32.png) [@mainer](https://community.cartalk.com/u/mainer)\
**Post date:** [October 2, 2008, 1:11am UTC](https://community.cartalk.com/t/eratic-dash/20242/1 "2008-10-02T01:11:42Z")

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I have a 1995 vintage Infinity G20 that the Tach and speedometer needles seem to jump around on occasion. Does anyone know what might cause this?

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**Author:** ![Beadsandbeads](https://avatars.discourse-cdn.com/v4/letter/b/c57346/32.png) [@Beadsandbeads](https://community.cartalk.com/u/Beadsandbeads)\
**Post date:** [October 2, 2008, 1:23am UTC](https://community.cartalk.com/t/eratic-dash/20242/2 "2008-10-02T01:23:16Z")

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The two devices might share a ground connection. If they do, and this happens with both at the same time, it is probably the problem.

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**Author:** ![mainer](https://avatars.discourse-cdn.com/v4/letter/m/96bed5/32.png) [@mainer](https://community.cartalk.com/u/mainer)\
**Post date:** [October 2, 2008, 1:25am UTC](https://community.cartalk.com/t/eratic-dash/20242/3 "2008-10-02T01:25:21Z")

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I should have said the tach is almost never right and the speedometer is right 95% of the time.

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**Author:** ![mcparadise](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mcparadise/32/32_2.png) [@mcparadise](https://community.cartalk.com/u/mcparadise)\
**Post date:** [October 2, 2008, 2:04am UTC](https://community.cartalk.com/t/eratic-dash/20242/4 "2008-10-02T02:04:17Z")

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How do you know the tach is “almost never right?”

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**Author:** ![mainer](https://avatars.discourse-cdn.com/v4/letter/m/96bed5/32.png) [@mainer](https://community.cartalk.com/u/mainer)\
**Post date:** [October 2, 2008, 2:22am UTC](https://community.cartalk.com/t/eratic-dash/20242/5 "2008-10-02T02:22:54Z")

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The tach often reads 5000 rpms when idleing. Sometimes it reads 0. After driving for a while it peggs at the redline. I never cared much about it but now I am trying to sell it.