Tach Question

Hey Everyone,

Have a 2004 LS Impala.
Has about 100,000 miles.
When driving, my wife noticed that the tach was higher than "normal".
When she shut the car off, the tach didn't drop to 0.
With the car off the needle for the tach is about 1000 - 1500.
Drove the car and it seems "normal" but the tach acts crazy and seems like the speedometer lags. (doesn't respond right away with accelerating or braking)
Not sure where to even start.

Any help would be greatly appreciated!

Thanks, Kerch

semper fi!

This is usually caused buy bad stepper motors in the analog clusters, also check for a bad ground in the cluster, you will need a wiring diagram for this but it does sound like the cluster stepper motors for both gages, a site or google search for " erratic GM inst cluster gages" will reveal lots of issues here.