There are several circuit boards in that vehicle. Need to know which one you are looking for.
Mounts on top of the wiper motor
http://www.corvetteradios.com/ sells the bulbs for the GM k1500 radios. They have a diagram showing how to solder them to the circuit board on their site.
In the compartment where the jack is. It is in a black box by the pillar. Open lid and remove circuit board and replace it.
I just did this to my radio. You must remove the radio for the dash. Open the radio to reveal the circuit board and solder new bulbs on the board. I found the bulbs at Radio shack online.
There is a resistor/ circuit board near the heater motor that need to be replaced. You can get one from almost any auto parts store.
move the wiper connection around while somebody presses on the brake if brake lights come on replace circuit board to wipers my 94 chevy 4x4 did that found by accident 3yrs later was about to trash the truck
it is located on the front of the wiper motor.
The board is under the cap in the Wiper Motor.
in the back
it may have a cracked circuit board, my blazer had the same problem
Under the dash board on the passengers side.
on the dash board