'77 DomOnicDave

So, when I have the head lights on and I press the brake pedal - the driver side rear tail light goes out (both the running light and brake light fail). When the headlights are off and I press the brake pedal - it looks like my running light is turning on instead of the brighter brake light.

I've opened up the tail light assembly, changed the bulb, and cleaned the contacts. All fuses look fine. Wires to the assembly look good and this seems to be a recent issue.

Any suggestion where to start looking?

On a side note, I'm having odd temperature reading on my temp gauge. Sometimes it won't read above 150 and other times its showing 220 but I'm not boiling over I'm thinking these are two unrelated issues and I'm chasing them separately. I've changed the sending unit and I'm about to buy a new guage.

Gosh, give me a hammer and wrench before wire cutter and an ohm meter any day.....

...Roger...

Sounds like a ground issue. Ground a long wire to the neg battery term and run it to the taillight housing as a temporary ground and see if that fixes it,if it does clean and or repair the ground.
I doubt the temp gauge is related,thats probably a poor connection at the sensor.