I'm assuming the Suburban dash would be the same as pre-94 pickups with the climate controll in the box below the radio, if so, you have to take the climate controll panel out of the dash and go inside it. To do it(goin from memory here so bear with me), first take the dash bezel off, 4 torx screws, next I think there will be around 4 or 5 1/4" bolts holding it in, there might be some hidden by lower part of radio. Once it is loose disconnect the connector on the back. I really can't remember how to take the face plate off, not sure if you have to the top off the unit or if there are screws holding it on from the outside somewhere. Once you find what's holding it in, take it off, careful not to let the buttons get away from you. Once open you should be able to see bulbs in it somewhere. I'm sorry I can't be more help but like I said I'm going from memory and what I know about my '89's, and I have no idea what yours look like.