Turn indicators and hazards
 

1977 Targa (US model)
Weird goings on with indicators. I have followed an excellent thread "Understanding the Emergency Flasher Switch" from 2015/6 (SpyderMike) and tested the hazard switch OK, which seems key to the operations, but cannot explain why hazards need ignition on, or the turn signals dependence on the light switch:

- ign OFF - hazard on - all 4 turn lights on solid - should flash. 12 volts at term 30
- ign ON - hazard on - all 4 turn lights flash. 12 volts at term 15 as well as 30

This shows the basic wiring is good and the flasher unit works, but should not need the ignition on.

- ign ON, lights OFF - no turn signals, but should work
- ign ON, lights ON - turn signals on solid (one side at a time)
- ign OFF, lights ON - turn signals on solid (one side at a time) - should not work

With hazards off, power to the flasher unit should come from the ignition switch via the green/red wire at term 15 on the hazard switch. 12 volts is there with ignition ON. But the flasher unit does not operate, yet the turn signal on the requested side lights up solid, but only if the lights are switched on! I can only guess that somehow the light switch is feeding power to the hazard switch, but I disconnected the brown wire with resistor to terminal 58 on the hazard switch, which is the only link I can see.

Can anybody help?




http://forums.pelicanparts.com/uploa...1735645768.jpg

Just to clarify, the hazard switch is a 1579-08, but the pinout and operation seem to be exactly the same as the -09 variant described by SpyderMike.

Button in (off) - 15 >> 49 and 58 >> 31

Button out (on) - 30 >> 49 and L >> R >> 49a >> 31

This is not 31 but the positive end of the button internal indicator light (labeled K something, cannot read on diagram).

31 is standard labeling for ground.

When button is off, this indicator light is dim lit as it gets reduced power through the resistor and 58.

When button is on, this indicator light is normally lit as it gets full power through the closing of the four internal switches. So this power would have to come from one of the two vertical lines of which the end is not shown on your pic. Either the white/brown (or is it black?) or the brown/green. Just guessing.

Thanks for your comment, and sorry for the quality of the picture. I agree with what you are saying, but from a continuity check with a multimeter they do connect to pin 31 - it ignores the resistance of the indicator light.
The two vertical lines (black/white and black/green) go to the turn signals, and through the bulbs to earth.

Was any work done on the car between the time the turnsignals worked and then they didn't work?

Here's a schematic view of the '73 914 turnsignals which is extremely similar to the '77 911. This view is a easier to read. One difference is the hazard switch on the '77 has the extra pin 58 to bring power to the lamp when the vehicle is running. The 914 doesn't have this connection.

Notice there are no other connections to power or running lights. The only place the running lights and turnsignals come together is the front turnsignal bulbs which are dual filament running/turnsignal.

If power is on pin 49 of the hazard switch, then the flasher relay should work. If nothing on the vehicle was worked on between the working and not-working conditions, I would think the flasher relay is suspect.

Here's a couple of tests to do:
Remove both front turnsignal bulbs and see if the flasher works.
Remove both rear turnsignal bulbs and see if the flasher works.
Remove the flasher and check if bulbs light up w/ign, w/o ign, w/lights, w/o lights; hazard switch on/left on/right on.


http://forums.pelicanparts.com/uploa...1736808203.jpg

Thanks, I'll try that.