Dash board illumination not bright enough

Time for a new instrument cluster ! How to repair GM Instrument Cluster Speedometer Gauge Stepper

Take it to autozone an have engine codes checked,could be computer malfunction.

The system is computer controlled, you now need it scanned with a special tool called a GM "TECH2" scanner to check for fault codes.

Sounds like a voltage spike or sugre that is possibly constant. Probably thru the speed sensor/s. take it to a garae and have it checked with a computer. most places do this for free. If the computer is reading the same as the dash, then I would say it is the speed sensor. If the computer reads ) mph, then the dash has shorted. The dash itself is a computer also.

Your dash lites are on with headlamps off? I'd check the wiring for headlamp switch/dimmer. Not only check the fuses, check the fuse circuit for voltage, use a test lite. You could use a jumper to bypass dimmer, see if dash lites work.

should be under your dash on the driver side or under your hood by the battery

check with dealer.these are noted for instrument panel problems and are under warrenty up to 80000 miles.

Remove the 5 mounting screws from the instrument cluster trim plate and remove the trim plate. Remove the 4 mounting screws from the instrument panel face plate and remove the face plate.Remove the instrument light grid from the center of the cluster. From behind the instrument cluster reach behind the speedometer and disconnect the speedometer cable by releasing the tab. Pull the cluster forward just enough to detach the "check engine" light bulb from the center of the cluster. Remove the instrument cluster from the dashboard.

Hi:
the dash has seven or eight small bulbs illuminating the entire area, and approx 3 of them are for the speedometer/odometer area.

It seems odd that those are the first to go, but most likely the problem.
It often requires removal of the instrument cluster to swap bulbs. not too bad, but sometimes tricky.

its under the dash to the left of the steering column like the book says, and theres a black box with a black plastic nut on it, take the nut off and the fuse box is behind there. hope that helps you.