Jim, something else to try.

With everything otherwise connected as normal, pull fuses 9 and 11.
Now turn on the key and look at the turn indicator. Flip the turn signal
lever either way and the light should come on and stay on. Does it?

Did the alt led and oil led come on and stay on during the above?

If the turn led still did not come on but the other leds did, look at
the back of the 4 way flasher switch and find the black/white/green
wires that attach to a point on the back of the switch. Now touch a
jumper wire from metal ground to the metal where the black/white/green
wires attach in the connector on the back. With the key on the turn led
should come on every time you touch the grounded jumper to that lead of
the switch connector. Does it?

You may want to nick the insulation to expose bare wire on one of the
black/white/green wires if you can't get contact to metal inside the
back of the connector they go to.

Mark