Corvette turn signal mystery - remote help needed

I'm at my parents house looking at their 67 Corvette. The turn signals don't work. The bulbs work individually when I turn on the lights so I know the grounds in each corner are fine. there's good connectivity across the connector at the base of the column for each wire. The turn signal switch behind the steering wheel appears to be switching appropriately. The fuse tests fine via meter and we tried a new flasher just in case. It was working before, nobody touched it. I'm sort of stumped. I'm here for another few hours, if anybody has any ideas let me know. 

A 67 doesn't have 4 way flashers yet, does it?  Turning them on is always a nice test of circuit integrity.  You need to google a wiring diagram.  All four signal bulb wires come right back to the connector on the steering column.  There will also be power in from the brake light switch that lights up both rears, assuming Corvettes share the brake and turn signal filament in the bulb.  Brake lights work?  Circuit to the rear, and the signal switch are fine.  No brake lights?  Jump power to each wire out to the bulbs to see what happens

With all four out, I'd really be concentrating on power in to the flasher and out to the switch.

I hate wiring problems. I have no idea why I had to go staring at wiring diagrams, as it seems likely that I'm not the most likely to come up with something useful, and I'll make myself cross-eyed in the process.

Maybe I just want to get better at it.

Disclaimers aside, I was looking at:

https://www.corvetteforum.com/forums/c1-and-c2-corvettes/3628005-1967-wiring-diagram.html

(above is actually a '65) and

http://repairs.willcoxcorvette.com/wp-content/uploads/2015/09/67-wire-schematic-for-tracing-wires.png

and wondering whether you had voltage at the turn signal switch, which I'm relieved jibes with Streetwiseguy's closing remarks. I *think* you're looking for a purple wire slightly larger than the others (18g vs 20g) at the switch (maybe confirmable and/or more easily checkable at the flasher, if you've already visited there recently?)

Good luck!

GM's of that era, if it has 4-way aka hazard lights, will have two separate flasher cans. The one that plugs into fuse block is for 4-ways:

The turn signal flasher is mounted in a spring clip above or next to the steering column (circled in pic below):

Pix from 65 Corvair. Vette will be similar.

I only have one flasher can and it's clipped under the dash, nothing on the fuse box. I have brake lights now, I didn't have them before but it was the switch. That was a bear to change. All the bulbs are good, I checked them all.

It does have hazard lights but they don't work either. I see the switch working under the wheel and it can see it working on the meter.

Okay that was funny, it was a spot in the fuse block but no flasher there. When I put the flasher there the four ways work. now the signals doesn't work but everything else does.

And I have power to the turn single flasher

tuna55 said:

It does have hazard lights but they don't work either. I see the switch working under the wheel and it can see it working on the meter.

Now they do!

Jesse Ransom said:

I hate wiring problems. I have no idea why I had to go staring at wiring diagrams, as it seems likely that I'm not the most likely to come up with something useful, and I'll make myself cross-eyed in the process.

Maybe I just want to get better at it.

Disclaimers aside, I was looking at:

https://www.corvetteforum.com/forums/c1-and-c2-corvettes/3628005-1967-wiring-diagram.html

(above is actually a '65) and

http://repairs.willcoxcorvette.com/wp-content/uploads/2015/09/67-wire-schematic-for-tracing-wires.png

and wondering whether you had voltage at the turn signal switch, which I'm relieved jibes with Streetwiseguy's closing remarks. I *think* you're looking for a purple wire slightly larger than the others (18g vs 20g) at the switch (maybe confirmable and/or more easily checkable at the flasher, if you've already visited there recently?)

Good luck!

I don't see any power at the switch. Isn't it just switching grounds?

I'm not sure how to probe the switch properly, but it ohms out in either direction think. The horn works too.

If I recall correctly, you have power into the switch from the flasher.  When you engage the signal switch, it loads the bi metal strip in the flasher, which heats up and bends away from the output contact.  Now no load, it cools and bends back in to make contact.  You should have power through the flasher to the switch, then with the switch on, intermittent power in to the switch and out to the lights. With the switch off, you should have power to the switch, and if you use a big enough test light, it will flash when you backprobe it.

IIRC, that is.

What he said ^^, I think. That "ppl" wire (purple?) looks to me like it *probably* should be power to the signals by way of the flasher. I wouldn't take my reading is definitive, but it does seem pretty clear that from the switch through the bulbs to ground has to be the path, implying power into the switch. I'm able to make power to that wire make sense, but that's more context than certainty that I'm reading the diagram correctly.

And again, I feel better about my guess given that it jibes with the Streetwiseguy's take.

Is the second flasher a known good unit, or just another unit, also of some amount of age and function?

Jesse Ransom said:

Is the second flasher a known good unit, or just another unit, also of some amount of age and function?

Swapped flashers between the four ways and the signals, both flashers made the four ways work.

Jesse Ransom said:

What he said ^^, I think. That "ppl" wire (purple?) looks to me like it *probably* should be power to the signals by way of the flasher. I wouldn't take my reading is definitive, but it does seem pretty clear that from the switch through the bulbs to ground has to be the path, implying power into the switch. I'm able to make power to that wire make sense, but that's more context than certainty that I'm reading the diagram correctly.

And again, I feel better about my guess given that it jibes with the Streetwiseguy's take.

The purple wire has power and the flasher and the connection at the base of the column checks out. I could not probe the purple wire at the wheel for lack of time, but it's just a wire between the switch and the connector.

Streetwiseguy said:

If I recall correctly, you have power into the switch from the flasher.  When you engage the signal switch, it loads the bi metal strip in the flasher, which heats up and bends away from the output contact.  Now no load, it cools and bends back in to make contact.  You should have power through the flasher to the switch, then with the switch on, intermittent power in to the switch and out to the lights. With the switch off, you should have power to the switch, and if you use a big enough test light, it will flash when you backprobe it.

IIRC, that is.

That's my understanding as well but I don't have a test light I just have a cheap multimeter. Again I could not find a place to probe switch at the wheel because I didn't have time to take it apart. I'm gone now though so I'll have to think about it and see if I can tell my stepfather how to fix it from here.

EDIT: I think I had this page open and replied long after more had happened. Sorry...

In reply to tuna55 :

Do you have voltage at the directional signal flasher socket? Sounds like if there's power, the flasher would pass it along; just trying to isolate the problem as being either:

1. Getting power to the flasher, or
2. Getting power from the flasher to the turn signal switch

Which still leaves a lot of stuff on either side, but at least we know the flashers work, and we have a location to test.

Jesse Ransom said:

In reply to tuna55 :

Do you have voltage at the directional signal flasher socket? Sounds like if there's power, the flasher would pass it along; just trying to isolate the problem as being either:

1. Getting power to the flasher, or
2. Getting power from the flasher to the turn signal switch

Which still leaves a lot of stuff on either side, but at least we know the flashers work, and we have a location to test.

Yes I tested battery voltage to and leaving the flasher headed to the base of the column in the purple wire. 

This may not be relative but does it have dual element bulbs?

I ask that because I've had similar issues only with the old style headlight bulbs in my Opel GT. Couldn't get high beams to work on either headlight. I did all the multimeter testing and couldn't understand why it didn't work when it had power. Had an extra bulb so tried it in both spots and high beams worked with the extra bulb. What are the odds of high beam element in both headlights go out at the same time? Well, gotta be something because it happened to me. Replaced both bulbs and all was good.

wlkelley3 said:

This may not be relative but does it have dual element bulbs?

I ask that because I've had similar issues only with the old style headlight bulbs in my Opel GT. Couldn't get high beams to work on either headlight. I did all the multimeter testing and couldn't understand why it didn't work when it had power. Had an extra bulb so tried it in both spots and high beams worked with the extra bulb. What are the odds of high beam element in both headlights go out at the same time? Well, gotta be something because it happened to me. Replaced both bulbs and all was good.

I checked the bulbs manually, everything's good and both filaments are fine and they are even the right bulb. Also they work as brake lights and as four ways. Good thought though!

arnt there some bulbs that need to be a certain way in the plug to work properly? Like if they are 180 degrees out they wont work properly?

Make sure the hazard switch is pulled all the way out.  When I got my '69 the turn signals and hazards didn't work.  It was as simple as pulling out the hazard switch.  It had been pushed in half way.