I received a shipment of 3-watt LED lamps and a low-load flasher relay from superbrightleds.com yesterday. The bulb bases were the same, so replacing the bulbs was easy. I ordered the CF13GL-02 LED flasher relay, which is a plug-in replacement for the Porsche 914 relay and responds to the much lower current pulled by the LED lamps.
After installing everything, I found out that the LED flasher was able to detect such a low bulb current, that it was stuck in the "on" mode (relay clicking) all the time. I measured 3 MegaOhms between the bulb output terminal and ground, even with all the lights turned off. I'm guessing this probably comes from leakage through grease or other leaky paths in the system.
Soooooo, I guess it's time to reverse-engineer yet another component that doesn't work...
Here's my dining room table with the test setup. I drew out the schematic of the LED flasher and got the datasheet for the PNP transistor that was activating the circuit.
Here's the modified flasher relay. Without going into too many details, I replaced one resistor and shunted one terminal to 12V with another resistor so that the input ignores loads with a higher resistance than about 200K ohms.
I'm a bit discouraged that people are selling this relay knowing it doesn't shut off in a real automotive environment.
Addendum: Here is the partial schematic for the LED flasher with suggested hack to fix the flashing problem with a leaky terminal.
Ah well, I'm happy with the results, and the flashing LEDs look great.