1967 Eldorado headlights did not work

As we had a very nice evening I wanted to take the 67 Eldorado for a spin.
When I took the car out of the garage I noticed that the headlights did not come on, but the taillights worked.

I suspected that the light switch must be the problem... I unplugged the connector of the switch and tested if 12V power was coming to the switch through the wiring.
There was one hot wire and I connected it directly to the headlights and they came on.

I then wrongfully assumed that the switch must be the problem then...
So I decided to take it out and inspect it.

Getting this switch out is a real pain as there is one screw thats almost impossible to reach. You can only get to the switch from underneath the dash btw...
It took me a couple of hours to get it out lying on my back under the dash...

I then opened up the switch and when I opened it up it fell apart immediately. I had a really hard time getting it back together correctly. Before that I cleaned everything inside.
I measured it with the multimeter and everything was fine.
Getting the switch back into the car was even more difficult than taking it out... There is this one d*mn screw thats almost impossible to get back in. Try to avoid to take the switch out, as you can measure if it works with the multimeter. I did not read the electrical diagrams carefully enough, so I did not measure it correctly and so I took it out.

!!! Be aware that the headlight switch on the 67 Eldorado is almost impossible to find, as it is a very special switch with the vacuum valves! If yours has twilight or auto dimming its even harder to come by!!!

As it turned out my switch was o.k. and the headlights did not work for another unknown reason... So I googled the problem and to my surprise I found my own website with a solution!
I had completely forgotten that I had the very same problem with my headlights a couple of years before and found a solution back then. I was just lucky that I do use my website as a sort of diary for the repairs I do on my cars.

As it turned out the same fusible link had burned through again. It runs very closely to the headers to the starter on the positive battery cable. Maybe it got too hot and failed or just broke apart. I could not see any melting or signs that it had burned through. It looked fully intact from the outside and I could only see that it was defective when I removed the insulation...

To replace the fusible link you have to take out the positive battery cable and replace the fusible link. Thats not a big deal. I rerouted the cables a little bit this time and hope that it wont fail again.

The 1967 headlight switch with automatic dimming
the light switch out of the car
Seen from the side - you can see the vacuum valves

Be very careful if you take the switch apart - as some parts will fall out...

The red cable on top is a fusible link and it caused the problem. I could not see from the outside that it was broken under the insulation.

The headlights are back in working order