For some reason, suddenly, now when I apply the turn signal, even though only the selected side exterior lights flash normally, both dash indicators now flash simultaneously (like modern emerg. hazard lights). The indicator lights don't seem as bright as before, but it is hard to be sure. Before I dig out all the electrical manuals and start to sort this out, I am just wondering if anyone out there has had this exact same issue, and knows what is causing it?

6 VOLTS/POS. GRD. NW INDIANA

Saw this problem on a '56 Tbird. It was a bad ground on the dash pod. The '56 had a small grounding harness that looked like a spider behind the dash and one of the legs broke off. I made a temporary ground connected to the metal turn signal bulb housing and a known good solid ground like the radio.

When I get a chance, I'll crawl under and make sure both indicator sockets are firmly pushed into the metal dash pod, as there is good reason to suspect they thus may not both be properly grounded.

6 VOLTS/POS. GRD. NW INDIANA

Make sure the metal dash pod is grounded too.

I have to assume the pod IS grounded, since all other dash lights are working.

6 VOLTS/POS. GRD. NW INDIANA

Well, it's fixed for now. I reached up behind the dash and twisted & pushed on all the bulb sockets.  It's so cramped up there (you CAN just barely fit your hand in behind, but there is no room to turn or grasp), you can't get your head far enough behind the dash to see what you are doing without compressing the clutch.  I can't be sure until I look at the schematic, but it seems like the signal sockets (as with the idiot lights) may be the 2-wire type that carry their own ground, and are insulated from the grounded dash pod (?), in which case there may be a frayed/shorted wire or contact that I moved serendipitously.  Whatever.  What a nightmare.  I would have to pull the radio and the hard oil gauge pressure line & bracket I installed (and maybe the heater controls & clutch pedal also) to conduct any extensive wiring repairs, so here's hoping the indicators continue to work.

6 VOLTS/POS. GRD. NW INDIANA

The painted dash and vinyl covering on the ledge where the dash pod sets has been blamed for the poor grounding of the pod. That is the reason for the
spider like cluster of wires to assure a reliable ground. I have seen that tightening retaining nuts on the pod sometimes make things work again.

Daniel, I don't mean to scare you, but just one caution. I've rewired several mid fifties cars, and every one of them had the insulation brittle. As long as it's left alone, it's generally fine, but it can crack when disturbed. So go easy if you're back under the dash.

The ground problems get worse as our car age, and rust and corrosion forms between bolted panels. I like to use an electrical connection coating (coppercote is my favorite) whenever I put something back together that might be a ground path. Likewise on the + connections. It's messy, like anti seize, but it works.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

For cracked insulation or even bare wires there's a product called "Liquid Tape". I bought some at Harbor Freight and it works great. Seems to be liquid neoprene. Use two or three coats to be sure and try not to breathe the fumes.


"FREE SAMPLE"

A bit 'off topic', but as long as the issue of old wiring has come up, I believe the most important thing you can do is rig safety circuit breaker protection into the main electrical feed from the battery, since there is no fuse to the dash/body wiring in 50s era cars.  Many a vintage car owner who parked with the battery still connected has been awakened to find his car/garage ablaze.  An inexpensive 30 amp breaker between the solenoid & the big yellow wire through the firewall will prevent the inevitable disaster that follows when old insulation under the dash fails.

6 VOLTS/POS. GRD. NW INDIANA