Here is the scenario:

Four ways work fine

Right signals work fine

Left signals flash (front and rear) when you hold it in the passing position

Left signals do not flash if clicked on, rear lights solid, front does not light

Both front bulb elements have continuity

Left front bulb socket has continuity to ground but no power when the left signal is clicked fully on.

Can someone please recommend some troubleshooting tips?

It's my 68 Lemans BTW

Have you changed the bulbs on the LF side?  1157 are 2 filaments.  1 can easily be broken.

8 hours ago, JUSTA6 said:

Have you changed the bulbs on the LF side?  1157 are 2 filaments.  1 can easily be broken.

I checked the front filaments for continuity and the rear flashes ok so I'm guessing it's good.

Bulbs can be so wonky....  If you don't want to spend the $$ for a new one just to check,  swap out the bulb with one from the other side.  While you have them apart, clean the contacts on the bulb AND the copper strips in the socket.

From what I gather..The 4 ways work...Right turn functions Correctly (both lane change and in full locked in turn mode) ...The left turn functions correctly only in the lane change mode...But it doesn't function properly only when it is clicked all the way into the locked left turn position...??

For what it's worth...I would strongly suspect that the turn signal switch (inside the steering column) Itself could very well be the source of the issue..(something burnt/out of alignment/worn out/broken .. ETC..) Might be worthwhile to pull the steering wheel and give the switch a good hard look/possibly Replace (it can be easily done) the turn signal switch...

TLBT..

Edited August 1, 20241 yr by TWO LANE BLACK TOP

Thanks guys, I will try new bulbs and then look at the switch. From what I see of a new one, the switch is not very complicated.