Turn signal indicator 64 Barracuda- help me understand

I got tired of tearing my turn signal switch apart every six months when my lights quite functioning correctly so I replaced my turn signal switch in my 64 Barracuda with one of the Daniel Stern replacements. When I got it back together the turn signal indicator (the single one for both R & L on the 64 Barracuda /Valiants) doesn't work. The switch is specifically correct for 64 Barracuda. I checked for voltage and there is flashing current at the tan and light green pins on the plug to the dash panel for each, one with right turn one with left turn. Bulb tests good and lights when current is passed between pin B & G in the photo. Test light does not illuminate when connected across the same terminals of the plug which indicate to me a ground is required and that is what is shown on the factory service manual diagram. My question is, how does the bulb ground when one pin leads to the bulb contact and one pin leads to the base? B and G terminals and bulb socket X. The only thing I can figure is the switch should provide ground through the turn circuit not turned on at the time and my new switch isn't doing that???
Somebody please explain it to me. Thanks!

During testing did you ground the housing?

Electrical Accessories & Service (Session 207) from the 1965 Master Technician's Service Conference

The schematic they use works like this:
The portions in yellow represent the moving brass contacts in the turn signal switch.
All three contacts move together when the signal lever is moved.
The black circles are contact points that do not move.


For example, left turn signal.


Current flow represented in orange arrows.

grimreaper said:

The only thing I can figure is the switch should provide ground through the turn circuit not turned on at the time and my new switch isn't doing that???
Somebody please explain it to me. Thanks!

Click to expand...

For '64 it looks to me like the left and right should both go to the same side in on the circuit board.
Which copper traces on the board are ground?

This one a ground?


If so the circuit is completed through the missing bulbs?

THAT INDICATOR LAMP DOES NOT GROUND and is not supposed to in this application, here is how it works

The lamp is connected between the hot leads to the left and right indicator lamps. Those lamps are grounded, and they are large wattage, that is, low resistance lamps. The indicator is a low wattage, that is, higher resistance lamp

When you "let's say" signal to the left, the left side is flashing and the power from the left front feeds to and through the indicator lamp. HOW does it get a return path? Easy. It goes to ground through the RIGHT side lamp.

This puts the two lamps in SERIES. Because of the wattage difference, the indicator lights up bright, and the unused front lamp likely does not even glow. The lamp doing the turn flash up front of course is unaffected, and flashes normally

How to get it working? Obviously somting wong

Are both front lamps working properly? That of course is the first thing because if one of them is not grounded, or not getting a power path through the bulb, then the indicator won't work on either side

By the way an LED will not work in this case, it must be a "plain ol lamp."

Thanks 67Dart273. I figured it must use the other circuit of the signals somehow but wasn't sure how. This explains it very well. I've been working on these cars for almost 50 years and had never dealt with this. Never stop learning! All of my turn signal lamps work but I'll clean up everything on my front signal connections to ensure low resistance and see if that helps.

OK I cleaned up my front Turn signal connectors and the housing grounds and my indicator is back! A bonus is my turn signals are a lot brighter now too. Must have left too much paint and not enough ground. Anyway once I had a decent understanding of how it was supposed to work it made finding a solution a LOT easier. Thanks again!!!

Interesting circuit- I learned something too.