Mine did it too, and it drove me crazy until I read a post on this site that told me what I needed to do to fix it.

There is a capacitor in the instrument cluster that needs replacing.
A search on this board should reveal the exact details.

The capacitor needed is a 470uf Electrolytic capacitor
(Radio Shack - 272-1030) I believe it is the largest capacitor on the board, and certainly the only 450uf so it should be easy to find if you can't find the other post.

The cluster has to be taken apart pretty far to get to the back of the PC Board to solder the new part in. Also, it takes a fairly high wattage Iron because the PCB is pretty thick in that spot.

If you want to do it yourself and are not experienced in soldering electronic components I recommend pulling the cluster and finding an electronics technician willing to do the detail work for you.

FWIW, the newer clusters with the non-mechanical odometers do not have the problem.

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