I have a 69 camaro that I am having problems with the turn signal lights. They come own and seem to kind of flicker, but no flashing.I have changed the flasher to a heavy duty flasher, checked for grounds, and changed the turn signal switch in the steering column. The other strange thing is the running lights, they work on the side markers (brown wire), and on the tail lights the outer bulbs which have two filaments(one for brake and one for running lights) everything works fine but the other part of the tale light has a separate bulb (one filament) just for running lights has no power (green wire).I don’t know if this problem is related to the other but this is not correct either. Brake lights work, emergency flashers work also front and rear.
The emergency flashers use the same wiring as the turn signals and brake lights. So that’s all good. The turn signal power feed to your new switch is suspect. Remove the fuse block and see what the back side of it looks like. Sounds like a bad connection.
Also, you may want to go back to the regular flasher, the ‘heavy duty’ ones are for using a trailer, I think.
I agree with Caddyman. I would look for a faulty connection to power for the turn signal circuit. The ground side appears to be ok since the brake light circuit works ok.
The side running light issue may be related if they are tied to the turn signal circuit. If not, there most likely a bad power connection to them also.
The way I would tackle this is with a schematic and verify all supply voltages (as suggested) Clue us in to what you actualy did to verify grounding.
Wild idea is fuse box inspection (not just the front side) and perhaps replacement of fuses that look good to the eye but may have high resistance (we are dealing with glass fuses aren’t we?)
I would only work this job by the hour,no flat rate possible here.