I have a couple of questions before ripping into my dash. My dash lights (speedo, gauges) are very dim. I can't even see the illumination during dusk/dawn. It must be completely night to see the dash lights. (yes, the dash control **** is completely counter clockwise). I have read in the fix-it books about a instrument voltage regulator and wanted to know if this is the culprit. Is it located behing the dash?

In addition, on the steering column is the transmission indicator which is not illuminated. I have looked all around to find a misplaced bulb/socket but have had no luck. Was this illuminated from the factory or was it assumed you would know what gear your transmission was in at night without having to see it? (no, I don't need to see it to know )

Specs: 78F250(4x4) Auto w/ tilt steering.
All dash bulbs replaced. No change to dimness.
Wiper/Lights indicator bright.
All other eletrical functions perfect. (??)

 

how much voltage are you getting to the lights?
There could be high resistance in the circuit somewhere, a corroded connector will do it.

 

I don't know how much voltage the dash lights are getting. I'm not even sure how to check that being on a circuit board. Is there such a thing as an instrument voltage regulator (in addition to the battery voltage regulator under the hood).

 

"Is there such a thing as an instrument voltage regulator (in addition to the battery voltage regulator under the hood)."

It has neither of those but, it does have a alternator voltage regulator.
Take the cluster out(don't unplug it), remove a bulb and use a multimeter to test voltage with the turned lights on at the bulb contacts. also test the voltage on the bright ones too, are they the same, they should be.
your meter should be set to DC volts.

 

There is an instrument voltage regulator. The printed circuit board attaches to it utilizing a plug resembling that of a 9-volt battery. The IVR attaches to the instrument cluster housing/back plate. I purchased one a couple of years ago at a local parts store. They are probably available through one of this site's advertisers. To answer your original question, I don't know if that could cause the lights to be dim.

 

The transmission selector is illuminated by a bulb which is located under the steering wheel. It used the same bulb as the instrument lights. Probably not one of Ford's better ideas but it was probably cheaper then running a fiber optic system.
My dash lights are also non-existant at dawn and dusk. I've tried every type bulb I can get my hands on to no avail. If you dismantel your instrument cluster, there are filters over the bulbs for the general lighting. Removing those will give your all kinds of light. Only problem is the lighting is white instead of the blue/green it is supposed to be. A company called "Jam Strait" makes a replacement bulb which is LED. This may be brighterthen the origional but I've only been able to find it in amber and it needs to be in white. And finally, yes, there is a voltage regulator on the back of your instrument panel but it is for the gauges, not the lighting.

 

I took mine out and checked. Mine has 11.5 volts at full brightness and 7.5 at lowest.
If you don't have at least 11 volts at full. Touch the red meter lead to the lightblue/red(stripe) wire where the wire goes in to the back of the connector on the cluster. Touch the black lead to a good ground. What is the voltage there? measure twice.

If you get 11 volts or more at full, check the light filters. The one for the light/wipers has a metal cap under the filter with a small hole. I made the hole in the cap bigger. That really helped. I don't know if the gauges have that cap.

 

Thanks to all. Great recommendations!
I replaced all bulbs months earlier and noticed the blue/green filter in the middle of the dash and thought it was to "cloudy" to allow good lighting. If all checks out, I'm thinking of removing it and going with colored bulbs. This is all a minor nuisance but fixing this stuff is what I enjoy most about owning an old truck. I guess the Xmission indicator will have to wait til I'm ready to break down the steering column for rebuild (soon).

 

I have dim lights too, I took off the green caps and it did brighten them up, but I hated the white lights. So I put some ELECRTRIC BLUE 194 lights in, still way too dim and the rheostat did not work, so I put a new switch in, still no rheostat function. I also saw a thread here about using chrome bumper paint on the back of the housing, tried that too. Now I see that the instrument panel voltage regulator won't help either, it only controls the power to the gauges. So does anybody have any other tips to share? I really hate driving at night, unless its pitch dark its tough to make out the gauges. Anyone think I need the whole new circuit board?

Thanks in advance!

 

try cleang the grounds, new swith and the reostat does'nt work? bring it back or clean the coil with a pencil eraser make sure the contacts are clean the circuit boards rarely die rub all the cotact points with an eraser to clean the goo off them. 25 plus years of dirt makes for alot of resistance

 

Have you checked the voltage to the lights? This was mentioned earlier in the thread...

 

i replaced mine with led bulbs super bright spark blu .75 a bulb with shipping

 

There are a number of posts here on how to clean and rework the flex circuit on the back of the instrument cluster. The electrical connections were only supposed to last 10 years. A cleanup is long overdue. Don't forget the dielectric grease.

 

Problems resolved.
Checked voltage: 11.5
Cleaned printed circuit.
Pulled blue "filters" off and used green colored bulbs. Works great and has plenty of lite. Even looks vintage. I tried blue and clear; both were to brite.
Xmission selector bulb was burned out. Replaced and now have all lites functioning. Thanks again for the advice.

 

I know this post is old now but I just found something everyone might be interested in. Replacement LED lights in a 194 package! Just replace all your old filament style with a plug-n-play part. Colors are Red, Super Yellow, Ultra Green, Pure Green, Super Blue, and Ultra white. There are two levels of brightness, look over at the column under intensity. A mcd of around 2800 is the same brightness of the standard 194 bulb used in the dash or clearance lights. Around 8000 mcd is stoplight bright! Open up your dash and replace all the bulbs and remove the now old and clouded lens covers with the new LED lights and have any of the cool colors available. Just google Mouser Electronics.
The part number is 697-01TWB7UW12 for the Super Blue color but the mcd is 1600 so it might be a little dim. I have always liked RED dash lights so
I am going to order part number 697-01TWB6UW12, which is rated at 2800 mcd. Oh! Don't forget the bulb under the steering wheel. I don't have anything to do with mouser except as a customer. I am an electronics hobbyist and repair old radios for fun along with my old 74 Ford F-100 Super Cab camper special.