Last night I was driving home in my 66 Monaco and noticed it was running hot, which is not normal. The headlights were on and I rarely drive it at night. When I turned off the headlights the gauge came down to normal, turned the lights back on and up it went. I am sure it is a false reading but why? The charge gauge was in the middle. And the lights appeared to be normal brightness.

Any help would be appreciated...

 

The joy of driving a 45 year old car,electrical gremlins! I would check the connections on the alternator and regulator,and make sure you have a good ground on the regulator. Also the bulkhead connectors could be a little corroded after 45 years.

good luck,john

 

Ok I will check it out in the morning, those are great suggestions. I was thinking possibly a bad voltage regulator, but I quess that would be messing up everything else. Not?

 

This is perplexing, to say the least. I would think this drastic a change in charge voltage would have shown on the ammeter, and it SHOULD HAVE also affected the fuel gauge, did it appear normal?

The only shop manual for 66 I have access to is for Plymouth, can be downloaded from My Mopar in the tools /reference section, but comparing the Fury diagrams to Monaco diagrams there appears to be at least minor differences in instrument cluster wiring.

The fury shop manual shows the instrument gauge "voltage limiter" is built into the fuel gauge. It might be a grounding problem in the PC boards of the instrument cluster. It may be that the grounded shell of the dash lights are somehow affecting the gauges.

On my 67 dart I had a lot of trouble with cluster PC boards making connections

Polara/ Monaco diagrams from My Mopar:


http://www.mymopar.com/downloads/196...araMonacoB.JPG

http://www.mymopar.com/downloads/196...araMonacoA.JPG

The 66 Plymouth factory service manual, which you can download from there:

http://www.mymopar.com/downloads/ser...ice_Manual.zip

The page numbers of the manual are not indexed correctly, you have to "hunt around" to find them. The under-dash wiring is on page 296-297 for the Fury

 

I'm an electrician. DC is a different animal than AC. And my favorite favorite saying on cars is "If it dont work...check power. If it works weird....check grounds!"

 

440 Roadrunner now that you mention that, when I first got the car I had an issuse with the instrument lights on that cluster.That was 5 years ago and this car has come along way since then, but its still not perfect.

Guess I better check the grounds...