Spee.dometer and rpm will stop working and start back up on it's own
instrument panel is beginning to quit working. gas gauge still works on 2004 Isuzu Ascender
I have not seen this problem on that Isuzu but we do not work on too many Isuzu Ascender. It may be a bad electrical connector behind the dash or a failing instrument cluster. Next time the instruments fail strike the dash with your hand and see if the instruments start to work again that would signify the problem is connection or instrument cluster related. Wiggle wiring harnesses at the fuse box and under the dash with the engine running while some one looks at the instrument cluster if you wiggle a particular harness and the instruments fail focus your attention on the connections in that are a and see if you have poor electrical contacts there.
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The instrument cluster needs repair. Visit http://www.mrwhizard.com for repair of these clusters