This thread should help. Explains how the flasher and indicator circuits work. It's not as straightforward as you'd think.
http://www.914world.com/bbs2/index.php?show...c=47236&hl=Anyway, I believe that the early ('70-'73.5) cars had the two turn signal indicators at the top of the tach- a left and a right. High beam is at the bottom. Sometime in '73 it switched over to one signal at the top left, and the high beam indicator at the top right. The one indicator served both directions.
If you read through the explanation in the thread, probable causes of your problem are:
- secondary relay in flasher busted. Need new flasher.
- you have lights that are drawing much less current than is required to energize the secondary relay. Are you using LED turn signal lights? That would do it. Either live with it, get rid of the LEDs, or add resistance in parallel with the LEDs to increase the load.
- wiring. Check the blue and white wire that comes from the flasher and goes to both indicator bulbs. Be sure it's not off or broken. If it is, both bulbs will flash together when either turn signal flashes.
- Another reason is if you have corrosion in the connections leading to the lights, or in the sockets themselves. Corrosion would limit the current in the circuit, maybe not enough to keep the bulbs off, but enough to prevent the secondary relay in the flasher to work. In this case, fix the corrosion and the indicators will start to work PLUS your directionals will be brighter.
good luck.
Jim