Ok, so I know that using the bench harness for ME.7 that Pin 3 needs switched 12V and pin 62 needs constant 12V but I need to know how it works in terms of the fuel pump. This is just a guess but tell me if I'm close...

- Pin 62 gets constant power to ECU as a base of when the car is working
- As ignition gets switched to "Accessory," the ECU wakes up and kicks the fuel pump over for a second. How does the ECU know to only turn the fuel pump on for a second? Is this a map with a timer built in?
- When turning the car to "ON", how does the ECU know that the motor is actually turning now? Does it rely on the cam/crank sensors to let it know?

I'm having a problem where when giving 12V to pin 3, the fuel pump continuously kicks on.

TIA,
Clint

Right, well how does the pump know to turn off then when priming?

Thanks for the response. Any idea what wires are what on the ME.7 B5 S4 ECU? I've been checking this pin-out



I'm assuming I really only have to ground 1,2 and obviously get power to 3,62 but which one gets switched and which gets constant? Currently I have 62 on constant and 3 on switched

Right that's what I'm curious about. I've been looking at the wiring diagrams a bunch I'm gonna see if I can figure this out

saw this in a me7.4.4 document:

"When the ignition key is in the cranking position (+CC), the ECU controls the fuel pump via the double relay for 1-3 seconds, if no engine rotation appears.
When the engine speed exceeds 20 rpm, fuel is then permanently supplied."

I appreciate the responses. What is happening is the pin 85 that goes to the ECU pin 65 (fuel pump relay) is getting 12V and not closing the loop for the fuel pump to open.

So you're saying that it references the crank position sensor first? it should at least prime if that were the case