I'm assuming you have air brakes with a dash mounted parking brake release valve - if not, ignore these suggestions.
On my Coach the parking brake valve is mounted under the driver's left side dash panel. It's a somewhat flimsy plastic panel. I can see it flex when I push in or pull out the PK brake knob.
If yours is the same, maybe when you push in the knob to release the brakes, the metal body of the brake valve is touching some of the wires in that area. On my Coach the area around the PK brake valve is jammed full of rocker switches and wiring. If that is the case you may be able to test this idea by lifting on the valve knob (not hard enough to reapply the brakes), but enough to move the valve/panel a little. If that temp fixes the issue, you know where to look.
My other thought is that when you release the parking brake, the air pressure switch mounted on the PK brake valve is shorted (meaning one of the wires is shorted) and sending voltage to other circuits in the dash. To test this idea you need to get access to the back of the brake valve and disconnect the wires to the pressure switch. Then see if the problem goes away.