[Outback Porsche]

Quote de Outback Porsche

Did you see my write-up on the sequence of events for a engine start? It explains how the DME/relay/sensors all work.

I'm not sure i was stalking every thread on the internet before I joined here, link me!

Took a little while to find ;-)

Here's how the DME relay works;



When you turn your key to ON, the first relay is energised. I stays energised in the START position. This relay provides 12V to the DME (pins 18 & 35).



When the key is in the START position, 12V is also provided to the DME on Pin4. Through circuitry in the DME, this 12V causes a GND out on Pin20 that energises the second relay and turns on the fuel pump.



After the car has started, Pin4 no longer has 12V to provide to the DME circuitry that provides a GND for the fuel pump part of the relay. But with the engine running, the speed sensor sends its signal to the DME and again through the DME circuitry, it produces the GND signal from Pin20 and keeps the fuel pump running.



Cheers,