EL-74 of the '97 manual shows the dash lights running off a 10A fuse labelled 61 on the diagram, which runs to what I'm guessing is the headlight switch. I assume the + feed for the dash lights tees off of the circuit for the tail light/corner light/parking lights (first click on the headlight stalk). If that fuse is blown, I'd expect the headlights and corner lights to be out, too.
If you grounded the radio to the pink/black stripe wire for the dash lights, you probably overloaded the dimmer switch and fried it. Unplug the dimmer. It should have three wires in its plug. Pink with a green stripe is the same switched + that goes to the dash lights and corner lights, pink with a black stripe is the dash light ground (controlled by the dimmer), and black is body ground. With the parking lights on, you should have 12v between pink/green and black, and if you jumper between black and pink/black, the dash lights should come on at full brightness. (Be careful not to short pink/green to black while you're messing with the plug.) If this all checks out, but the lights don't work with the dimmer plugged in, replace the dimmer switch.
When the dimmer broke in my '93, I took it apart, desoldered the plug from the circuit board, soldered the two ground pins together, and plugged the resulting jumper plug back into the harness so I'd have dash lights until the replacement dimmer came in.