The problem is with my '70 GTO, but I assume an A-body Buick would be similar. The high beam indicator does not work. Tried changing the bulb to a new, known good bulb and still doesn't work. So I assume the problem has to be in the circuit board that feeds all the gauges and dash lighting. I don't want to have to try to find a circuit board and then tear the dash apart to replace it. Is there a hot wire that comes off the dimmer switch that I can tap into to power a separate high beam indicator? Maybe I can mount a small indicator light in the ash tray or something.
You can run a jumper wire to the existing high beam indicator. Of course this does mean disassembling the instrument panel... Personally I would take it apart and get a good look at the instrument panel. Maybe its something easy to fix on the dash itself? Your call of course.
As a technician I would be looking at the traces on the board and the contacts for the bulb. Try to see if you can follow the trace to the next solder point, and look for continuity. You might find a broken trace or a cold solder joint (If a solder joint is smooth and rounded, it is good, if it is bumpy and sharp, it is suspect and I would re-flow it.) If you find a broken trace you could repair it with wire. Scratch the trace to reveal good metal on either side and solder a wire in. Insulate the repair with clear nail polish (Has to be clear, coloured nail polish can conduct electricity) Time consuming, but the proper way to troubleshoot. The repair process is entirely your call. This is my opinion.
