Sounds as though you have isolated the problem. The fact that the high beam indicator doesn’t work would seem to me that the problem is between the dimmer switch and the headlights.
My dad had a 1939 Chevrolet where the headlights would sometimes go out. The taillights would stay illuminated when the headlights would go out. Several mechanics,looked at the car and couldn’t find the problem because the lights would be working when they checked the car. In desperation, my dad had fog lights installed so that he,could turn on the fog lights when the headlights failed and have some illumination. After a year or so, the problem was traced to a bad connection at the dimmer switch… Electrical problems in cars even back then were sometimes hard to find.
Well I had the last two days off and I replaced all of the wires that were showing signs of insulation degradation and my headlights work very well now. Thank you for all of your suggestions. the high beam wire from the dimmer switch was broken between the switch and the first terminal block so no high beams. Funny thing though the high beam indicator wire is fed from the high beam wire connected to the dimmer switch right before the first terminal block so that is why no High beam indicator light I replaced the horn wire from the steering column to the horn relay. The brake light wires attatched to the master cylinder brake light switch. The temperature sending unit wire. Both high beam and low beam headlight wires from the dimmer switch to the first and second terminal blocks. The horn output wire from the horn relay to both horns.to the horn relay wire. I relplaced the output from both terminal blocks to the asphalt looms for each headlight bucket and both parking light wires from each terminal block to the parking light asphalt looms. I figured the wires inside the asphalt looms would not be deteriorated. I used non insulated terminal butt splices to connect the wires from the terminal blocke to the looms and put heat shrink on all terminal ends. I used fiberglass cloth covered wire for all of the except for the low beam output from the dimmer switch. I am very pleased with the appearance and the performance of the new wires in my car. When I have some time I will post pictures of the replaced wires. Again thak you all for the suggestions the multimeter helped me isolate and identify exactly where the problem was. Looking at that problem helped to identify how deteriorated most of the wires under the hood were.
I am glad you have working high beams and reported back to us with the solution to the problem. I really like cars of the 1940s through the early 1950s. My first car was a,1947 Pontiac Streamliner fastback 2 door that had the same GM B body as your 70 series Dynamic. Cruiser. I had to modify the lighting circuit to install turning signals as turn signals weren’t standard equipment back then. I had to change the front parking light sockets to allow dual filament bulbs and run a wire to the right rear tail light. Is,your Oldsmobile the inline 6 or the inline 8 and is it the Hydramatic or a manual shift?
Good job. That was a lot of wiring.
Replacing the wires is certainly a pain in the behind job, slow and boring and usually physically hard to do. You end up standing on your head and bending and twisting, and I can’t see things close looking up because my bifocals don’t work that way. I finally got a pair of near distance glasses just for jobs like this one. But what you did is necessary and it sounds like you fixed a lot of problems and future problems. Congratulations. Maybe your friends and neighbors think you’re nuts, but we understand completely.