911T hazard not working

[piggdekk]

Hi,
I'm chasing some electrical greemlins (blinkers, brake lights, hazard...) to make sure that my '71 911T will pass the periodical road test, and I'm now fighting the hazard lights. The blinkers are working fine (already fought a gremilin there in the front headlamp), but when I press the hazard switch I can here a cracking sound coming from the dash and the blinkers don't work. At times they may even work, but most of the time there is only noisy. Do I need to change the relay behind the speedo? Is it an available part. Don't seem to be able to find it here in PP.
thanks
luca

[Eddyvdw]

I had the same problem. First thing to check is the relay and the ground.
This didn't solve my problem so I cheated a bit and connected blue/white (coming from C on the relais to lights at rev meter) to ground. All works fine now (for over a year already) :-)

Ed

[piggdekk]

Thanks Eddy,
how do I check if the relay is bad? Is it just a normal round relay or is it a special one? I haven't pulled the gauges yet.
thanks
luca

[Eddyvdw]

You need to get the flasher relay out to test it. Use the electric diagram to figure out what the relay should do.

Our host sells (of course) the relay. Part number 914 618 303 11

You can test the switch as well.

With switch off,
30 connects to nothing (infinite ohms)
15 connects to 49, nothing else
L, R, 49a connect to nothing
Brown is ground

switch on:
30 connects to 49, nothing else
15 connects to nothing
L, R, and 49a connect to each other, nothing else
Brown is ground

[piggdekk]

Thanks Eddy,
the fact that my blinker work just fine, is an indication that the flasher is ok? As far as I've understood the difference between the normal blinkers operation and the hazard is that they share the same flasher, but 2 different relays. Need to find a proper diagram to sort it out.
I'll try to keep the post updated
luca

[piggdekk]

just to update and help other who may have a similar problem. Tonight I managed to spend some time fighting this gremlin. I've started measuring the voltage at terminal 49 of the flasher, and the voltage was low, about 8.9V when the emergency switch was pushed. So I went down checking all connections first after the switch, and then before the switch. At the end the problem was caused by some oxidation on the 6 pole connector below the dash, plus some more oxidation on the fuse number 2, that actually powers the emergency lights. once they were both cleaned and the fuse changed, I could again read about 12.4 volts at the pin 49 of the flasher and the emergency lights were working again.
luca