The passenger door window winds down 5mm every time I open the door. I guess it is to clear the soft top roof, but it doesn't wind back up again when I close the door. If I play with the door handle, all these 5mms add up and the window completely winds down. If I use the window controls to wind the window back up, they work fine.
I don't have the same issue with the driver side.

I'm expecting to have to take something apart, but I don't know where I should start.

 

You need to reset the windows. Roll the window all the way down and hold the button until it clicks. Then fully up and hold until it clicks.

 

Bladerunner is correct that you need to reset the window travel as he says, but the usual reason for just one window to lose its setting is that the battery is either discharged or is at the end of its life. If it's older than 5 years, then I would replace it.

Richard

 

How simple a solution and it worked! Many thanks

 

As @RichardS mentioned, your battery might need replacing. If the windows act up again then check the battery voltage after the car has been sitting overnight without any charger connected. It needs to be 12.6v or higher.

These cars are requiring a battery that can hold full voltage all the time, or you will have many electrical gremlins.

One proven thing you can do to extend battery life is to connect a quality battery tender to the car whenever it is not being used overnight or longer. Brands that are popular here are the NOCO Genius, CTEK, and the Del Ran Battery Tender +.

Z

 

The windows thing is the canary in the coal mine. The windows will notice small voltage drops often before other systems get glitchy. So, as others have pointed out, if you see this happen, and you haven't disconnected the battery recently, then it's time to verify battery voltage.