There are certain points on these cars that can be a real PITA
THE FACT that your headlights work (and nothing else?) is important
Refer to the diagram in the 72 manual I hope you downloaded. Page 8-150. (Engine compartment is page 8-147)
On page 8-150, scroll down to the "steering column" There you'll find the connections in the connector going up "into" the column. This is the turn signal switch, and NOT what we are interested in
Scroll down to the next page on 8-151 and again find the "steering column" This time the pictured connector is the one for the ignition switch
The wires are labled by CIRCUIT- SIZE-COLOR
So on the left side of the connector, find wire labled "J1-12R-battery"
This means wire no. "J1", no12 wire size, Red, and it's coming from the BATTERY
Probe this with a meter / test light and see if you have power
If you do, move to the second one down, "Q2-12BK-ACCESSORY. Turn the key to run, and then to "accesssory" and see if this wire is hot in both cases.
If the black is cold all the time, you may have an ignition switch/ switch connector problem
IF the red coming in is bad, this is "complicated," because you have headlights.
Scroll down to the bottom of this page (8-151) and find a big diamond shaped symbol with a "1" in the middle.
THIS IS CALLED the "number one splice" and is a big splice (factory) wrapped right up in the under-dash harness, between the bulkhead connector and the fuse panel/ ignition switch.
Notice the middle right wire, no R6A-12BK. THIS IS THE MAIN POWER coming from the battery or alternator feeding INTO that splice from the ammeter.
Notice the top right L1-16BK. THIS FEEDS off to the headlight switch, and indicates that this splice is at least partially still "together." NOT FUSED
Notice Q3-14R bottom right. This feeds off to the fuses in the panel which are "hot" with the key "off." Check the fuse panel with the key off and see if you can find any power there. If you do, this wire is OK. If not, that splice is BROKEN
Does the horn work? the bottom left wire coming off the splice, H1-16V feeds off to the horn relay. NOT FUSED
The middle left, R6-12BK goes up to the next page and goes to connector "P" on the bulkhead connector. This goes out into the engine bay and goes to the alternator output stud.
The fact that so much does not seem to be working means that you need to do some of these tests to separate the problem into "major parts" so you can narrow it down.
All these old girls are having troubles with the bulkhead connector, it would pay to pull it apart, inspect, and clean the connectors, and examine for burn damage. If damaged, there's a number of ways to deal with the problem from there.
