electric pas pump

[Pirvu Eugen]

Hello!
I know that was discused before about fiting an electric pump for steering and change to vacuum the brake servo.
I have done the brake vacuum servo and i bought an electric pump from Mercedes A class. My problem is that this pump has 3 wires. 1 big red for the +, 1 big brown for -, but has another small blue one.
Can somebody tell me what to do with that blue wire?
Please!
Thank You!
Eugen
Iff the thread is in the wrong section...please excuse me.

[Jamo]

Your asking on an audi forum what the extra wire is for a Mercedes pump?

Probably a speed signal

[Pirvu Eugen]

Sorry... i thought that some guys wich have done allready this modifications had same problem. I thought that all the electric pumps have tis wire for pressure adjustment. i dont know what voltage send throw that wire. Will be nice to have an manual adjustment for the steering pressure in form off an poti...
Dont know!
Thank You!