Instrument Lights Quit Working

[John Moore]

I just finished a complete interior restoration on my 71. As part of the restoration, I replaced the headlight switch and all instrument gauge bulbs. After I reinstalled all of the dash pads and buttoned everything up, I discovered that none of the gauge lights worked. What's strange, is that I tested them immediately after installing the driver's side pad and the center instrument cluster and everything was ok. I checked the fuse (lower right of fuse panel the one marked "gages") and it's ok. The headlights,taillights, side marker lights work, which tells me the headlight switch is functioning. What could my problem be?

John

[Ed Jennings]

Re: Instrument Lights Quit Working

John, I'm not sure that fuse marked gauges feeds the panel lights as well. Check all the fuses. The most likely thing I can think of is that the panel is not grounded properly.

[John Moore]

Re: Instrument Lights Quit Working

Ed,

I did a visual inspection without pulling the fuses and all appear to be okay. Maybe I need to pull each one. As for the ground, I know I hooked up the 2 ground wires on back of speedo and tach. Don't remember one behind the center guage bezel. What has me puzzled is they were working right before I finished the job. Maybe I pulled something loose when reinstalling everything. I am afraid this is going to be one of those things that will be darn near impossible to figure out.

John

[Jim T.]

Re: Instrument Lights Quit Working

John from what you have posted, even though you installed a new light switch it is possible that the resistor wire that conducts the juice that powers the dash lights could of failed. Do your interior lights come on when you twist the light switch?

[John Moore]

Re: Instrument Lights Quit Working

Jim,

Yes, my interior courtsey lights come on when I turn the headlight switch. Does this give you any other ideas?

John

[Bill Stephenson]

Re: Instrument Lights Quit Working

John,

I have seen instances where the headlight switch was worn out in such a way that the only function that seemed to be bothered was the dash lights.I think,specificly,that the reostat(if you want to call it that)that allows the dash lights to vary in brightness is the culprit.Often wiggling the stalk and knob will get the function back.At least try this so you can eliminate it as a possibility!.......... Bill S

[John Moore]

Re: Instrument Lights Quit Working

Bill,

What has me puzzled about the reostat suggestion is that the switch is brand new. I replaced it because the reostat on the old switch was broken (the dash lights did work with the old switch). Several people have mentioned the reostat as the possible culprit, but given the lights worked with the old switch and a broken reostat, I don't think that is it. However, i would be the first to admit I don't know much about car electrical systems! John

[Joe L.]

Re: Instrument Lights Quit Working

John-----

It is possible that the switch you got was defective, or failed fairly soon after installation, with respect to the dash lamp function. I had this happen once with respect to the courtesy lamp function on a new switch.

Otherwise, check the fuses. The fuse which controls the dash lamps is a short one, not the "traditional" length Littelfuse. If it turns out to be the fuse and if a replacement fuse burns out, too, post it here. In that case, I may be able to help you.

[Ed Jennings]

Re: Instrument Lights Quit Working

John, try attaching a temporary ground wire to a known good ground. You can attach it to the battery negative post and be real sure of your ground. Try attaching it to ground points on teh dash with the light switch on and see if anything happens. If not, try installing your old switch. If they work then, you have a bad switch or a bad connection. I assume all youe terminals are in a plastic block. One of these goes from the switch, to the fuse panel and back to the lights. I don't have a shark wiring diagram handy so I can't tell you which one. Be sure they are all connected solidly.

[John Moore]

Re: Instrument Lights Quit Working

Joe, Ed,

Thanks for the solid tips. I saw the short (appox 1/2") in the lower left of the fuse block. If that is the one you are referring to, I will check it this evening. As for the suggestion on a temporary ground, I thought of that as I was stewing over the problem at lunch. I have just such a jumper already made up that I used to troubleshoot my backup lights. I will try that if the fuse checks out. Let's hope it's the fuse! I will report back tomorrow. Wish me luck, I am ready to get this project over and get back on the road.

John

[Wayne W.]

Re: Instrument Lights Quit Working

Two fuses actually control that circuit. Are your tail lamps working?

[John Moore]

Re: Instrument Lights Quit Working

Here is what I found out last night. Turns out the small 5 amp fuse was blown. I replaced it and the lights worked! Unfortunately, the fuse blew again. In fact, the fuse blows so quick that the lights don't even come on. It's like it is blowing as soon as I put it in the holder. What's stranger, is that I replaced it with a 10 amp fuse, and while it does not blow, the lights still don't work. Any suggestions?

John

[Ed Jennings]

Re: Instrument Lights Quit Working

Yikes! That doesn't sound good at all. Something is dead shorted. It may not be easy to find. If you have the dsah out you could remove all the lights, turn the switch on, and then ground the sockets one at a time and see if you find the problem that way. You could also check with an ohmmeter between the each lamp's hot wire and ground for continuity. I wonder if one of your sockets could have the power wire touching the inside of the case. Good luck

[John Moore]

Re: Instrument Lights Quit Working

Good suggestions Ed. The biggest disappointment is that I will now have to take the dash back apart to do any type of testing. I really don't relish the idea of having to do that again. I am probably going to let it stay like that for a few weeks and drive in the daytime only. It's almost spring here and I am itching to go for a crusie. Shouldn't be in harm in driving it as long as the fuse it out and on power to the lights. Agree?

[Ed Jennings]

Re: Instrument Lights Quit Working

John, I feel your pain! I would cautiously agree that it probably won't hurt to operate the car with the fuse out. Makes me a little nervous though to have something I know is shorted under the dash. Make sure all your other lights are working. I had a "dash light" problem on my 62 when I first got it. I drove it a bit even at night with intermittent dash lights. What I didn't realize at first was that the tail lights were also intermittent. Switch was the problem in this case. I changed it as soon as I realized the tail lights were going out also.