No, it isn't a chicken ...

What actually happens is that when if I turn on the headlights, the engine dies.

The car is a 1967 Chevelle SS 396. About a month or so ago, I noticed that the radio would cut out when I pressed the brakes and after investigating ( car is unchanged from how I bought it 5 yrs ago ) I noticed that there was like a 10 gauge wire connected to brake switch. This 10 gauge wire ran to a 2nd fuse box where the radio was connected.

So, is this an issue where current is following the path of least resistance and resulting in a volt or output drop on other, smaller paths? Can a bad battery or alternator cause this kind of thing to happen? I have driven the car for such a long time unchanged and I have to say that it is amazing how gremlins can just pop up in a car that has been sitting most of the winter. Go figure ... Anyway, any comments or suggestions will be greatly appreciated.

Oh yeah ... signal lights work with headlights off, but do not work with headlights on ... Just another symptom suggesting that there is not enough juice to go around ...

Thanks in advance ... Steven

Does the engine crank and the car start ok?

What's your voltage when the car is idling, and at 2000 rpm?

Check at the battery, the horn relay, and every fuse, to ground.

Thanks Jim ... The good news is that the car will crak right up ... I do need to do a voltage test with the car running ... I am suspecting that my alt or voltage regulator probably has me borderline on output. Last fall I was considering upping a a higher output, internally regulated alt. I may revisit that thought this weekend ...

I would remove the power source for the second fusebox from the brake switch and reconnect it to battery, or close to it as one could.

Get all the electrical problems solved before changing alternator.

Yeah Everette... I will look at how that 2nd fuse box is fed. Obviously, with the brake switch incoporated, it has to be a constant feed. If it is tapping something other than direct battery connection, I will move that.

BTW, car is showing 14.65 volts at battery at idle ... about 14.8 at back of alternator... 10.5 at the coil with lights off ... A little over 5 volts at coil when I turn the headlight on. My ignition is stock dist with Crane conversion and I still have yellow starter and cloth resistor wire intact.
Car cranks and runs fine until the headlights are turned on.

Is there any grounding incoporated in the light switch?

I plan to do some extensive circuit tracing, probably starting tonight...

sdt

My ignition is stock dist with Crane conversion and I still have yellow starter and cloth resistor wire intact.
Car cranks and runs fine until the headlights are turned on. sdtI'd replace/tie back the cloth covered resistive wire with a 12 AWG wire from the fusebox (IGN) spade. But then read Crane's instructions for wiring first.

what are you reading at the fusebox, and at the horn relay with the lights on?

Guys, as usual thanks for comments and suggestions ... I think the problem is solved. While walking through all of the circuits and the connectors I discovered that the headlight harness in the engine compartment was starting to separate from the back of the fuse box. Once pushed entirely seated onto the back of the fusebox, all of my symptoms has disappeared. That is great since there is a cruise-in tomorrow evening. I am 95% sure that this did fix the problem. Thanks again ...

sdt