Dash lights dim on Mustang

Sounds like you've already found the problem, if you're only getting 10.5 volts past the headlight switch/dimmer and 12 volts when it's bypassed, that's a big restriction.

My guess would be if you jumpered across the dimming circuit and had the engine running, 14 volts at the bulbs would be a major improvement.

Remember, small problems often have small solutions. Fix the stuff that you KNOW is wrong before looking for wierd or more complex solutions.

Good luck,

Greg
[addsig]

Oh, the Instrument Voltage Regulator is just that: It has no function other than to provide the gauges with a constant 5 volts, so it would not be your problem.

71-73 Dash Lights are inherently Dim at night..

My fix for my 73 Mach:
Removed Gauge dash
Removed bulbs
Carefully Removed Green Diffusers
Went to Wal-Mart and bought replacement colored bulbs (bluish/Green)
Worked Wonders at Night .. I can see gauges!

I thought about just sticking the Clear bulbs back in .. but did not want to experience the other extreme of Bright light in my eyes .. however, the bulbs are behind the back plates and this may just work but you would loose the "color" tint..

-dc

1993Bolt, I replaced the headlight switch last night and immediately noticed an improvement, but in the never ending search for perfection I will probably try your approach.
Thanks to all who replied.
Danny

Problem solved. I removed the blue/green diffusers from the dash panel lights and reinstalled the original clear bulbs. Much brighter yet not bright enough to be annoying, just right in my opinion.
Thanks to all.
Danny

Good Job Danny ..
If I get at it again, I'll test clear bulbs as well .. but until then, I'm much happier with the diffusers removed and blue tint lights ..

-dc