There's no single "under dash turn signal" on a 1992 Chevrolet Lumina Euro on the driver's side (or anywhere else). The turn signal switch itself is usually located on the steering column, not under the dash. The flashing indicator light for the turn signals is on the instrument panel.
Any flashing lights or components *under* the dash would likely be related to other functions and not the turn signal system itself. If you're having trouble with your turn signals, the problem is more likely in the steering column switch, wiring, or a blown fuse/bulb.
