Some pics of the lemans when you have chance. I like the early ones particularly. Pontiacs had good looks and instruments which I liked.
You must know by now in the old car world new is not always good or right. :( Sometimes it is, sometimes not.
Correct bulbs?
Off the top of my head shouldn't be in the turn signal switch.
That switch doesn't even get power when the key is off.
A check could be made for that and or a back feed at the column connector.
You have the Barracuda supplement?
There's also pdf of that diagram here by
@1969383S
1969 Plymouth Barracuda wiring diagram (not mine)
Make sure you got the '67. There are small changes each year.
This gets back to Mike's point about grounds.
Lets say the ground for one or both of the front parking lamps is weak or loose.
View attachment 1715666384
Then the next easiest path for electricity to flow is through a turn signal indicator.
Something like this.
View attachment 1715666394
That's another reason to see how the outside lamps are working or not under each situation.
