Had a right side taillight bulb burn out in my '70 Skylark and quickly replaced it with one from my stash of bulbs on hand. Noticed shortly thereafter crazy things started happening: when the right turn signal was on, the left and right side rear lights flashed, except when the headlights or parking lights were on at which point the flashing stopped. Oh, did I mention the dash lights were flashing in sync with the taillights? The left side turn signal worked OK except when the headlights or parking lights were on; the flashing stopped again. Checked fuses, flashers, ground wires, connections from the aftermarket tach and FM converter - no luck. Want to guess what the problem was? When I changed the burned out bulb I assumed the card I took the bulb from had the correct bulb; it didn't. Instead of being an 1157 the bulb I put in was an 1156 and it must have been shorting out everything because once I put the correct bulb in, no more problems. Could it have been that simple or just a coincidence? Should I be looking for other problems or be happy with the way things are working now?
funny story, glad you fixed it. The 1156 is a single filament bulb and won't work for turn signals and brake lights on your Buick. The 1157 has two filaments and is the correct bulb. The one filament burns when the the parking lights are on and both burn when you hit the brakes or turn signal. The only place on your car an 1156 bulb should go is in the backup lights.
