RPM Gauge reading high

[scooter38]

it goes up and down smoothly as you give it gas and it idles down
but its just reading way too high, at fast idle its pegged, at normle idle it reads like 3000 rpms, its just reading too dang high, does this sound like a gauge problem or maybe a bad wire? any idea where to start would be thankful, this site is so informative, its awesome ,i use it all the time for advice, i have a 1988 s-10 blazer 4wd 4 speed auto tranny, 4.3L z TBI engine...thnxx

[16th hippy]

if th engine is not really idling that high, it will most probably be the tach itself. unless you wanna take the cluster out and reset the needle. if not done right can seriously mess up the tach, and it seems it is already bad anyway, but is worth a shot. otherwise only other way i know of is to get a new cluster put in(the whole thing).

[scooter38]

i wasnt aware that you could "reset the needle" how woulkd you do this? assuming the cluster was took out....thnxx

[16th hippy]

well, with the cluster out, genlty pry on the plastic tabs locking the outer cover to the base. this will expose all the needles for all gauges. GENTLY pull the tach needle off, and re-install it pointing to zero. without putting the cover back on, hook the cluster up to the vehicle, start the engine and verify that the tach is working in the correct range.

due to a brain fart, i forgot to ask this. with the engine off, and key out of ignition, does the tach still read wrong, or does it drop to zero?

[scooter38]

when i cut it off it stays on whatever it was reading, then when i just turn the key to on position it drops to like 100 rpms but not all the way down to bottom of cluster........so wahat would that mean you thnk? bad gauge or just need resetting?

[16th hippy]

both....only reason i suggest even trying resetting the needle is a new cluster costs a few hundred+/-. it sounds as if the tach itself is bad, but i don't think that can be replaced seperately.....you could mount an aftermarket tach right in front of it and let it go.