Background.

I had a problem with passenger side window motor - wouldn't go up or down. Clearly an electrical issue - a silent issue. Checked the switch and wiring - all good. A connector leading to the motor shows +12V or -12V when the switch is operated. Solution - replace the motor.

Problem.

I bought a used motor from a reputable ebay seller. Plugged it in - no signs of life. Well, things happen - it wasn't tested I thought. Got another motor as a replacement - the seller is now aware of the issue and claims that it was 100% tested, I believe them. Plugged this one in - same thing, no life. Now I'm curious if I should have reset something after replacing the motor to make the system "aware" of a new item. Although I'm a bit puzzled anyway as my basic electric knowledge tells me that if I have 12v on the connector when the switch is operated - everything should work!

Any ideas?

Jammed window?

Seized cables?

Are you changing just the motor or the whole regulator assy?

I'm not sure how they work on a Fiesta

I would check the wiring in the plug between the door and body for broken wires 

2 hours ago, DaveT70 said:

Jammed window?

Seized cables?

Are you changing just the motor or the whole regulator assy?

I'm not sure how they work on a Fiesta

Mechanically all should be good. I attached the motor to the wiring first - the cog does not move, no sound or attempt to move. So it does not work even before installed.

57 minutes ago, dezwez said:

I would check the wiring in the plug between the door and body for broken wires 

But the motor plug does show stable voltage

Stable no load voltage may be correct - ie 12V, so you may get this with a voltmeter, but if you have a high resistance source, as soon as you try and draw any current, the volts will drop !

I got caught out by this years ago, so I always test with a test lamp across the voltmeter.

Put a test light between the 2 wires in the plug, rather than 1 end on metal, and operate the switch. It should light up which ever way you operate it. If it doesn't then you aren't getting the earth returns which comes from the passengers window switch in the drivers panel.