sounds to me like every thing is fine if you can power up the servo from the black connector and it moves im no pro with nsr wirring but i am a auto electrition
and looking at the wirring diagram it seems the servo motor uses two wires the W witch id guess is white and W/R witch at a guess would be white with red trace the pgm must switch the pollarity to change the direction other wise it has a earth on the motor itself witch would mean that the W an W/R are both powers with a common earth switching power from w to w/r would change motor direction if this is the case.
it appears the other wires going to the servo are to tell the pgm were the servo is in its range of travel .
anyway if you can power the servo and it works the fault must be in the pgm or the input signals it uses to control the servo.
eg. maybe the servo motor works fine but the sensor inside is telling the pgm its at full open or somthing silly like that.
i have two working servo's so if you have anyway of testing yours i can compare your readings to my good one.
als0 my mc21 wont cycle the power vavles with the old key on unplug tps trick i dont know why but it will at 2500rpm so i set mine up with the hrc 10000 rpm trick.
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