What is the extra pin on the flasher relay for on the older model?
 

I am trying to source a replacement relay for my indicators that is compatible to LED bulbs. I have found one in the UK, but it is the 3 pin version (same as the "Hazard Flasher/Blinker Relay, 911 (1985-89) P/N 1H0-953-227-M5044"), but in my car at the moment (78sc) it should have the 4 pin version. I am considering trying to upgrade the circuit to the 3pin equivalent, but would like to know what the 4th pin is used for. Any info would be greatly appreciated before I attack the indicator/hazard wiring in my car :)

Bump... I have an '82 and want to find a better replacement too...

Hi!

You should be able to tell what pin does what by looking at the wiring diagram. I'm at work, so I don't have my manual, but usually the lines on the diagrams have the pin numbers labeled, so you should be able to figure it out.

Hope this helps!
Brad

I think for the four pin, the terminals are 31 (ground) 49a and 49 (input and output) and C (pilot lamp). This suggests that two wires are used to turn the unit on, one to light the pilot lamp, and the remaining single terminal to power the signals. The three pin that I can see on Pelican's web site is designed for 4x21W bulbs and Zero five-watt bulbs, which means there's probably no pilot terminal? If you can tell me the names of the pins on the 3-pin one I'll look it up in DIN 72552 and figure it out.

Yes, I sorted it all out, and it is in this thread - http://forums.pelicanparts.com/porsche-911-technical-forum/287390-i-solved-led-indicator-problem.html