Page 620 (B50) of the FSM shows separate ground wires for right and left turn sigs. If the right sig works and the left doesn't, the ground to the left is bad between the light and the main harness.
(Connectors 32A/32B)

I jumped the ground no change. Signal & flashers work but still no left running light and they work even with the ground disconnected, it's picking up ground from the frame. 10 volts off the blue wire nothing on the purple wire.

If you're sure of the terminals being good (BOTH ends,) then you have a break within the insulation of the wire.
Longshot~ Your multi-meter is giving erroneous readings due to a tired battery. (Not the vehicle battery, but the instrument battery.)

OP~ You're only getting 10V on any wire? This is a problem.

I'll change batteries in my fluke but pretty sure their good. Will recheck everything again.

Correction- the connector number is 31A/31B. Can you check continuity of purple wire from 31B connector to light socket?

OP stated that signal and emergency lamps are fine, just running light is inop. This tells us the ground is good.

The blue wire is the running lamp circuit , the violet wire is left turn signal circuit.

Changed batteries in fluke, not much difference, got 11 volts on blue wire and with left turn signal switch on I got fluctuations from 0 to 10 volts. Rechecked the black ground still nothing. Jumped black wire no change.

I'm getting 147 ohm on violet wire.

Sounds like the left side sleeve has gotten pinched. Black 144 ohm, violet 147 ohm. Especially if the light worked with ground disconnected. (post # 12)