Classic/Antique Car Repair: Dashboard lights on 1965 Mustang, dashboard lights, incandescent bulbs

Question
Hi, Dick -
I have a 1965 Mustang convertible. Dash lights are so dim they are useless. Do I need to pull the dash in order to get to the bulbs or can I reach them from underneath? My car isn't "concours" so I'm thinking about replacing the bulbs with LED....still have to get to them first however.

Thanks in advance if can help me.

Plaul

Answer
I doubt there is anything wrong with your bulbs, if they are lighting at all.

Most likely, the problem is an oxide build-up on your the dash light rheostat in your headlight switch - this is so common on these cars as to be almost universal.

The way to investigate this, and probably fix it, is to do the following:

Pick a dark night, so you can see what is happening;

Turn on the parking lights;

Now, grab the knob on your headlight switch, and rotate it, turning it from one end of its travel to the other, many, many, MANY times - while you watch the dash lights.  

If you have the patience to keep it up long enough, you will begin to see an increase in brightness - when you see this, set the control at the best brightness point that you see, and begin rotating it again, slowly widening the area where the oxide is rubbed off, thus bringing up the light level.  

What you are doing is polishing the nichrome resistance wire inside the switch.  When you get the whole range of motion as bright as you can get it, it will be as good as it was when the car was new, which should be adequate.  

If it is still not satisfactory,  you can put a brand new headlight switch in the car fairly easily - NAPA still carries them in stock, and they are not difficult to change.

You have to be careful about putting different bulbs in the dash lights - since they are fed from a variable resistance, changing the current drain to that of LEDs is going to make the control not work right.  If you put brighter incandescent bulbs in, you run a risk of overheating the plastic parts in the instruments.

So the bottom line is, try to get it working as well as it did when new - and see if you can live with it.

Dick