64: BULB FINALLY INSTALLED BUT CLOCK, GAUGE LIGHT AND RADIO DO NOT ILLUMINATE

[Norman Silverman]

HELLO ALL

So, after 4 hours work to remove and replace the bulb behind the "defrost" on the HVAC panel, the same bulbs that started me doing this are still out-even though I replaced all three of them. Those are the clock, the gague illumination and the radio. The gauges themselves work, and I tested each new bulb before I put it in and all worked perfectly. But it seems there's no power to these sockets. Does this ring a bell to anyone? Is there a common connection point where the wires for these three items meet?

Note: I replaced all the illumination bulbs with LEDs but that should not make a difference, all the other bulbs work- plus I did the same swap out in my 64 and 66 Imperials with nearly twice the illumination bulbs in each dash,  and every bulb worked afterwards. 

Stumped and injured (arms all cut up from removing and replacing that bulb on the HVAC control panel.)

Norm

[Russ Austin]

Power comes from the headlight switch. 

[Norman Silverman]

Russ.

Now I know where to start.  

In your experience, is it more likely to be a connection issue at the switch or an internal switch fault?

Thank you!

Norm

[Dennis P. DiBari]

Hi Norm,

     A lot of times with electrical connectors on the older cars, the connection could be bad.  I have used myriad times on my 64 Caddy the Electric Connector spray that I picked up at my parts store.  I've used it on headlight and blinker connectors.  It cleans the old connection and helps.  Just a thought.

Dennis DiBari

[Norman Silverman]

Thanks, Dennis. I will make sure all connections are clean, although those that I have seen look brand new-but that's no guarantee. 

Norm

[Norman Silverman]

Update-and its not good. 

After checking to make sure that the headlight switch was properly installed and the contacts clean (thanks, Russ), I removed the block that goes on to the back of the gauges, it has the illumination light and the GENERATOR and OIL lights mounted on it. At the suggestion of Dennis, I cleaned each friction ground contact on the block (four of them), cleaned all of the bulb sockets and reinstalled the bulbs.

With the block not plugged to the car but grounded and the headlight switch pulled out, the illumination light did light-BUT, neither the oil or generator light went on when the key was turned to "on." 

However, when I reinstalled the block in to the dash and started the car, the generator light did not come on with the key position in "ON" but as soon as the car started it came on BRIGHTLY. PLUS, the gas gauge and the temp gauge both started to weaken in their readings and finally no longer register. Something is failing. NOTE: the illumination bulb started to go bad gradually, by getting dimmer and dimmer till it went out entirely. I thought it was a bad bulb. 

I went to the battery with my gauge to see if the alternator had burned out, but I get a very strong charge when the car is running. 

Now, I am REALLY STUMPED. Any suggestions????

Is it possible the our cars cannot take LED bulbs in the dash?

Thanks

Norm

[Dennis P. DiBari]

Hi Norm,

     I know that some of the members did make the switch to LED bulbs and they worked.  Mine are still regular bulbs.  Not sure what to tell you with the other gauges failing.  Check if you disturbed any of the wiring in the process of separating the connectors.  These connections are 60 years old and delicate.  Wish I could help further, but stumped on this one.

Dennis DiBari

[Norman Silverman]

It was a FUSE!! The Instrument-back up light fuse had blown, which caused the gauges to not operate and the generator light to remain on. Very odd. 

HOWEVER, I have the same issue that started this all: the bulbs in the instrument gauge area and clock were originally bright when I turned everything on, but are now gradually dimming. I expect they will stop working just like last time. Something is either over powering them or under powering them.

Ideas?
Norm

[Dennis P. DiBari]

Norm,

     When you put the voltmeter on the battery terminals with the engine running, what is the voltage reading?  It should be approximately 14.4 volts.  If it is not consistent, the regulator is not working properly.  This happened to me and I was getting readings from 11 volts all the way to 17 volts within a minute; mercurial to say the least.  That is dangerous and can blow dash lights.  I changed the regulator twice, installed a new regulator harness, and doubled grounded the regulator.  Check that out to be sure.

Dennis DiBari, Cottekill, NY

[Norman Silverman]

Dennis

I put a battery condition meter on it and it registers a constant high. PLUS, this is happeing ONLY to the bulbs on the Gauge pack (1), the clock(1) and the radio(which will not illuminate). Something along the circuit may be shorted, but only for that section. The main panel lights, the Comfort control lights, the Transmission lights are all good and steady bright. 

Thanks

Norm

[Dennis P. DiBari]

Norm,

     Sounds right.  Has to be in that circuit.  The wiring is 60 years old and VERY delicate.  I try not to touch too much in that area.  Some good news for you with the regulator!

Dennis DiBari

[Norman Silverman]

I put back the incandescent bulbs in gauge pack, clock and radio and all now work, but not as brightly as I'd like. I think I'm done chasing this.

Biggest surprise was the constant illumination of the generator light as a result of a blown fuse that governs backup lights and gauges. Strange.

Thanks

Norm

[Dennis P. DiBari]

Norm,

     GREAT WORK - they work now so you are good with this!!!!

Talk soon.

Dennis DiBari

Great conversations!