I have a 69 cutlass and the car is completely dead. I don't have headlights interior lights, horn, radio, nothing. Battery is got 12.73 volts. i have been poking through the wiring but nothing obvious has jumped out at me. all the fuses are good inside. What am i missing here? What does this horn relay do? Does it bring power to the fuse block?

 

Clean the negative ground strap and where it is connected to body. Check the voltage regulator if it is shot will cause you to have no power. Check for dead shorts power will take easiest path to ground.

 

The horn relay will have a 12V distribution stud on it - should have 12V at all times to ground. Report back if 12V is there or not.
Could be a bad battery cable or fusible link. I have heard of some battery cables letting go inside at the lead connector that attaches to the battery.

 

Clean your battery and cable terminals and try again before you do anything else.

- Eric

 

x2

 

did this happen all at once or hit/ or miss for a while? the ground thing souds like the most likely solution but maybe try a jump just to make sure you have a good batery.

 

When I worked at a local auto parts chain a guy came in once looking for a battery for his 67 Chrysler Newport. He wanted the biggest battery we had so I sold him the 1000 amp unit. Next day he comes in all bent out of shape that the battery won't start the car. I told him it would start 5 of those cars at once. So I go out to the car and first thing I do is check the battery cables. As I grabbed the positive cable green dust poured from the plastic liner. All the copper wire had turned to powder, lol. Needless to say he needed cables.

Check your cables and especially the grounds.

 

Check the fusible link wire at the starter. Positive battery cable goes to the starter and then a fusible link wire goes from the starter solenoid to feed the rest of the cars power.

 

X2

I had a beater a few years back and the same thing happened. a whole bunch of the individual wires that made up the positive cable had broken about a 1/2" up from the terminal up inside the insulation. I would randomly loose electrical power for a split second when driving. if you looked at the cable it looked fine, but when I had it off and gave it a wiggle it was obvious what was wrong.