# Flickering lights

**URL:** <https://community.cartalk.com/t/flickering-lights/36996>\
**Category:** Maintenance/Repairs\
**Tags:** f250, ford\
**Created:** [September 22, 2009, 6:08pm UTC](https://community.cartalk.com/t/flickering-lights/36996 "2009-09-22T18:08:31Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![bismatt](https://avatars.discourse-cdn.com/v4/letter/b/439d5e/32.png) [@bismatt](https://community.cartalk.com/u/bismatt)\
**Post date:** [September 22, 2009, 6:08pm UTC](https://community.cartalk.com/t/flickering-lights/36996/1 "2009-09-22T18:08:31Z")

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all the lights on my 1985 f250 flicker,i have checked all the grounds every thing seems to be in order?

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**Author:** ![Roadrunner](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@Roadrunner](https://community.cartalk.com/u/Roadrunner)\
**Post date:** [September 22, 2009, 7:00pm UTC](https://community.cartalk.com/t/flickering-lights/36996/2 "2009-09-22T19:00:27Z")

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Do the lights flicker really fast, slowly or spasmodically?

I’m thinking a faulty alternator.

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**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\
**Post date:** [September 22, 2009, 7:11pm UTC](https://community.cartalk.com/t/flickering-lights/36996/3 "2009-09-22T19:11:27Z")

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Make this another vote for a failing alternator.

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**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\
**Post date:** [September 23, 2009, 12:47am UTC](https://community.cartalk.com/t/flickering-lights/36996/4 "2009-09-23T00:47:41Z")

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That is usually a sign of bad diodes in the alternator as the others stated. Bad diodes cause excessive ripple voltage so the lights flicker.