Issue with lights

[Darth Ooten]

I'm having some weird issues with the lights in my 1968 Gtx. First some backstory. This all started when I decided to fix my fuel gauge and figure out why the horn wasn't working. None of the gauge cluster lights worked so while it was out I installed a new circuit board and led bulbs. The wiring was a mess and rather than patch it back together I ordered a new under dash harness and installed new turn signal switch.

Now for my problem. When you turn on the park lights everything works, same when you switch the headlights on. The emergency flashers all lights work as they should but the dash lights flash as well. If you signal left the dash lights flash and both taillights blink. If you signal right dash lights don't flash, front and rear work correctly but the side markers don't come on.

Reinstalled old circuit board on cluster same result. Wiring seems to be solid free of damage. Grounds are clean. The fact that the passenger side market lights work under certain circumstances is what's really got me stumped.

Any thoughts?

 

[moparedtn]

The way these cars are wired, the dimmer switch on the dash lights actually is used as a "junction box" of
sorts for all manner of light wiring you'd normally not expect - and they're also a known point of issue
with failure/corrosion over the years, too.
If you don't have one already, I highly recommend getting ahold of a factory wiring diagram so you can
see what wiring is routed where.

By the way, member @devinism has been rebuilding the dimmer switches and like type switches for our cars
for many years now and does a fantastic job of it (my Fred the GTX has one of his dimmers in it) and can be
considered an expert on how all the lighting wiring is put together in our cars.

 

[davek]

check all your grounds.