350i door mirror wiring

[gas mart 1]

Hi All, can anyone explain the mirror wiring on my 350i, I have got a replacement motor which is the correct size and all bolts line up, but the replacement has only 3 terminals where as the original had 4. Looking at the picture of the replacement, the centre terminal feeds both motors. Does this mean I simply join two wires together ? if so which wires. The wires are black , white , blue , brown .I made up a test light to try and find out which wires , but the bulb seemed to light up which ever combination of colours I tried.
Cheers
Martin

Edited by gas mart 1 on Wednesday 26th October 18:18

[gas mart 1]

Thanks for all replies , I have now found the BMW 3 series ,4 pole motor, on flea bay , looks identical to the original .
cheers
Martin