Instrument Lights



I have been reading on this forum for a short time. I have a 66 mustang I6 coupe, white, ALL orginal. My uncle purchased the car off the original owner,did some interior work and some other minor things, then sold it to my dad. Anyway, the car has 107,000 miles on it. The engine has never been touched(minor things have been done, but no rebuild). It runs GREAT. My question was: when i turn on the lights, the instrument lights do not work. I know there are several things that could be the problem, the switch, blown bulbs, etc. I was wondering if anyone has ever had the same problem and had a idea of what was wrong. anyway, sorry to ramble! Thanks for the advice. Oh yea, and all the instruments do work!
Actually...mine has that problem sometimes...

Make sure the brightness adjuster isn't turned too far. I don't mean just to the side that makes it dim. I'm not trying to be a smart ass.

My instrument lights will turn off if I turn the adjuster too far to the bright side.

yea my bro's car does the same thing (he has exact same car except auto trans. and he has rebuilt the engine) but no luck doing that with mine. i just hope it isn't something so complicated that i have to tear into the dash and start replacing things. thanks tho
Does your radio lights come on?

There shouldn't be anything so complicated as to require the dash to be pulled out. You may have to remove the gauge cluster...but that should be able the extent of it.

actually, i had to install an aftermarket radio(i had to make a box to mount it under the ingnition because the dash has not been hacked out of it) because when i had the car painted the paint shop blew the radio starting the car off of those charger/starters. (i never could convince them they did it and gave up). the instrument lights did not work before that, so i know they didn't blow them. I meant having to take out the gauges when i said "tearing into the dash" ;) thanks for the help
Start by checking all the fuses. That's cheap and easy.

My car had the strangest problem with interior lights that turned out to be a grounding problem with the chrome heater/fan controls on the dash. Turns out that the bolts that hold that plate to the dash also act to ground part of the system. Mine was loose so the ground wasn't good.

Also, the instrument panel lights are grounded to the dash though the metal screws - very flaky. The fix on my car was to run a grounding wire off the back of the instrument panel to the a screw on the metal dash so the grounding is good.

Remember that the dash is used as ground for a bunch of interior lights. Check to make sure all the screws are there and things are held down tight.
the easiest thing to try first is the headlight switch. over the years of pulling and pushing, the contacts for dim adjustment wear out.

I think you can get it at any local parts house. just unscrew the dress ring securing it to the dash and then pull it out and replace it.

Replace your headlight switch with a 69 switch. That's the year they had 4 headlights, and they can better handle the juice of halogen headlights. ;)
Question, have you checked that you aren't grounding the radio through the original double connector? A common mistake is to think that connector has a positive and negative contact. It doesn't. Both are positive. One is for the radio light, the other is radio power. If you ground through the plug, you will send all the juice through the instrument panel circuit, and likely blow the intrument panel fuse. BTDT :oops:
actually the radio is grounded to the bottom of the dash(those big philips head screws) and all the taillights work. i did install xenon bulbs that "surge" when they are on. the instrument light didn't work before that though. i am not sure if the "surging" is a alternator going bad(not as strong as a new one) or too much electricity being drawn. they don't "surge" as much when the revs are up though. so it is better to use a 69 switch? anyway, thanks for the help
When you twist the headlight switch the interior lights come on? Mine didn't for a very long time (6 years) until I cleaned the contacts and made the grounds at each light a little better. I also replaced all of the old fuses with new ones. It looked as though the old fuses were corroded.

Good luck! Electrical stuff can be very frustrating. I have a wiring diagram that I can scan for you if you need it.

actually they don't. so to clean the contacts do you have to take the switch out? i figure you would, i have the shop manual so i could take a look at that. would the interior lights not working have something to do with the gauge lights? but how come the headlights and parking lights come on? yea like you said electrical is no fun. i don't like it at all. anyway, thanks for the advice. oh yea, i have replaced all the fuses with new ones.
Pull the switch! I bet the contacts that control the dimmer have worn out. If you turn the switch counterclockwise you should feel it hit resistance and then go beyond...this is interior light ON. Anything colockwise of this bump is dimming the dash lights.

My exterior lights always worked fine....but not my interiors. I would pull the switch out and clean the contacts, as well as get some new fuses. You might want to pull the instrument cluster out and just follow some wires around. I discovered that the factory stereo power wire had been pinched between the steering column and the dash for the life of the car.

Get a manual and a electrical diagram. Let me know if I can scan anything for you. Let me know how it goes!

thanks for the info! i'll probably wait until this weekend to do that. You think pulling the switch would be in the shop manual. ill go try to look it up. I noticed your in houston, you a big aggies fan. i'm heading down to a&m galveston next fall. thanks for the info!