Turn Signals - Stumped

[gotham22]

I have a 1978 280z that I am so close to getting back on the road after 4 years.  I can't get the turn signals to work and I am at a standstill.  After searching forums the obvious thing was to check the hazard switch (hazards work).  I jumped the green/yellow to the green at C7 to rule out the hazard switch.  With the wires jumped I see 12v at the turn signal.  Removing the jumper and keeping the hazard switch in-line I see 12v as well. 

As you can see in the picture, the connector to the turn signal has the following wires

G   WR  WB

GB  RY  RW

With the turn signal in the middle position I have 12v at the G wire and the GB wire.  When I move the turn signal to the up or down position the G wire drops to 0v and GB stays at 12v. When I return it to the middle position the G wire has 12v again.  

I also looked at the flasher unit under the drivers dash.  I have 12v on the green wire going in to it.  0v on the white wire.

At this point I am not sure what to do next.  Any ideas?

 

[Captain Obvious]

The simplest, most straight forward answer is "your turn signal flasher unit is bad".

Have you tried another one?

[Captain Obvious]

To provide additional detail to the above... It sounds like your flasher unit is not making a good solid connection across it.

It's a low enough resistance to provide 12V at the turn signal switch when the switch is in the center position (driving nothing). But as soon as you move the turn signal lever up or down, the low resistance of the signal bulbs drags the voltage on the white wire out of the flasher down to zero.

I'm thinking your flasher is fubar. Or the connections on the base are corroded. Something like that.

I assume you already checked the connector condition right there at the turn signal switch? Everything all nice and clean and shiny?

 

[SteveJ]

First, use the colors on the dash harness side of the connector, not the switch side of the connector. The switch colors do not necessarily match the wiring diagram.

The white wire is the 12 VDC source coming into the switch. There are two green/black wires. One is for the horn. It should have 12VDC to ground until to press the horn button. The other GB wire is for right side turn signals.

1. Turn the key to the ON position.
2. Verify you have 12VDC to ground at the W wire in the steering column. If you don't, you might have a bad flasher relay.
3. If you have voltage at the white wire, then turn the switch up for the right turn signal. If the W wire is at 0VDC to ground, measure voltage to ground at the GY wire on the flasher relay.
4. If there is voltage at the GY wire, you might have a bad flasher relay.

 

[SteveJ]

I think @Captain Obvious and I are having similar thoughts. Sorry about that, Capt!

[Captain Obvious]

8 minutes ago, SteveJ said:

Sorry about that, Capt!

Haha!! I'm thinking maybe you should be the one that's worried!!

[gotham22]

Thanks for the info guys. 

- I do not have any corrosion that I can see on the connections. 

-Steve J - The white wire on the dash harness side connects to the green wire (where I took the reading) on the switch side.  Those two are the same right? So my voltage test was accurate?

dash side = W GB GR

switch side = G WR WB

Not sure if this is a dumb question. Is the hazard relay the same because those work? Could I pull that temporarily and use it for the turn signals? Or is there a way to test the flasher on the bench? 

 

[SteveJ]

8 hours ago, gotham22 said:

Thanks for the info guys. 

- I do not have any corrosion that I can see on the connections. 

-Steve J - The white wire on the dash harness side connects to the green wire (where I took the reading) on the switch side.  Those two are the same right? So my voltage test was accurate?

Considering your first post was conflating the turn signal GB with the horn GB, I think you may want to go through the test I laid out.

8 hours ago, gotham22 said:

Not sure if this is a dumb question. Is the hazard relay the same because those work? Could I pull that temporarily and use it for the turn signals? Or is there a way to test the flasher on the bench? 

The flasher relay for the hazard lights is the same as the flasher relay for the turn signal. Yes, you could swap it over to test. However, both @Captain Obvious and I still wonder if the problem could be further upstream. That's why I prefer voltage readings over component swapping. However, swapping the hazard flasher relay would be much easier than bench testing the flasher relay. In order to have old style relays operate, they need sufficient current flowing through the relay to get the bi-metal strip to bend.

If you have a bad flasher relay, here is a two wire relay that still has a clicking sound similar to the old bi-metal flasher relay: https://www.amazon.com/dp/B07GWL1YS3

[gotham22]

Thanks.  Going to do your test now and will get back to you

[gotham22]

Finished your test and looks like you guys were right.  Going to buy the relay you suggested and see if that fixes it

12v to the W wire

with turn signal up 0v white wire

GY wire 12v

[gotham22]

BTW - Captain obvious.  Read your post  from April 28, 2016 which is how I knew to jump c7.  Thank you!

[Captain Obvious]

Glad to help. Hope it's as simple as a bad flasher. That would be easy!