Turn Signal Switch causing ignition Cut

[hogie]

The last couple of days I have been having problems with my turn signals not functioning properly. Usually the left signal would work and the right front would not. I took it upon my self to refresh the switch the usual way by opening it up and cleaning the ball, spring, and contacts.

I have probaly opened this switch up four or five times as the repair doesnt seem to stay working for too long and now the tabs have broken off. So I just replaced them with plastic clips held down by the screws on the side of the case.

However, that isn't the problem I have now. Whenever I turn on my left turn signal it causes the ignition to cut out in time with the blinker. The AMP meter tach and drop while the brake warning light also flashes. Pressing the brakes will prevent the signal from flashing. Signalling to the right doesn't appear to cause any problems, but actually works now.

The only other symptom is that the flasher will continue to click even if the the switches aren't engaged.

Does the ignition cut make any sense at all? I am going to pull the switch back apart tonight and see if I cant get rid of the problem, but thought you all might have some additional input.

Thanks

Edited August 31, 2010 by hogie

[SteveJ]

Yes, it does. Inspect your wiring. You would have to trace this out on a wiring diagram, too, because it depends upon how the circuit is designed.

You could have damaged insulation on wires in the harness. They cross-connect on the left turn signal circuit. When you put the turn signal switch in the left turn position, the flasher unit allows the circuit to close. At that point, there is an alternative path (with lower resistance) to ground. The current flows through this path, and the ignition circuit loses power. That would cause the other symptoms you describe.

Of course, the flasher unit heats up and opens up the circuit. This allows the current to resume flowing through the ignition circuit.

It's an old car. Insulation can age and break down.

Steve

[hogie]

I just printed out and traced the atlantic zcar 72 electrical pdf and didn't find any such crossover. I will defnately check for any damaged insulation, hopefully it will clear itself up once I pull the switch back apart. I really dont want to pick up a new one as they are mega expensive.

[SteveJ]

You won't find the cross-over just by looking at the wiring diagram. It would exist from the isulation being bad or owner/mechanic wiring problems. The wiring diagram would be helpful in identifying wire colors to trace.

[EScanlon]

Add to that that the wiring diagrams at Atlantic Z are woefully inadequate for anything else other than really basic troubleshooting.

The only one that I found there that even remotely looks like the Datsun wiring diagram is the "Basic S30" model one (Right hand column, billed as a 72 wiring diagram) and even it is incomplete for anything except the most bare bones of 1970 model vehicles.

Do a search here and you should find much better examples.

FWIW

E

[SteveJ]

Yeah, I didn't pick up on you using a diagram from Blue's site. Go to XenonS30. The link is in my signature.

[hogie]

I figured out the problem last night...apparently this will happen whenever the ball falls off the spring and the rocker plate wedges itself against the walls of the box. I wouldnt have expected it to cause the strange effects, but it certainly went away when I put everything back together properly.

[SteveJ]

Yeah, you made an alternate path to ground. I'd have to look at the wiring diagram to be sure, but my first guess is that the flasher unit was acting like a breaker and would open the circuit when it heated up. As I mentioned earlier, that opened up the short, and the car resumed as normal until the flasher contacts closed again.