I am having issues with my rear power windows on my 2005 Volvo V50. I am getting power to both motors. The drivers side moves down about 4 inches and stops. The passenger's side moves slightly, very similar to when windows are frozen closed due to ice. I checked all connections and power. This issue first started yesterday after a downpour and driving into some deep puddles, I got a message "slow down or upshift" and the car was running rough . After the car dried out seems to be running fine and no messages or CEL. Could theses 2 issues be related. Thanks

Thanks Bill,
I checked and cleaned the 4 grounds near the left strut, and the 3 grounds located by Rt strut mount also pulled seat and removed carpet. It was damp due to sun roof drain hose failure which I repaired. I checked the 3 body mount grounds that run just above floor pan in foot well area. I pulled the B pillar trim and did not see what looked like a typical "I" loop ground . Is the B pillar ground located down low by the rear foot well . I did not remove the top portion of the trim where the airbag side airbag is located. Thanks for the help !

Hello battery Checked out fine, 21.3-12.7 volts I pulled the seat and carpet cleaned all contacts and grounds still no fix to power windows.Power seat not working either. Power seat has been on ongoing issue. Wonder if all are related. Spoke to the dealer and they mentioned I may need a re program . I would like to check relays, first. Does anyone know where power seat and power window relays are located.

Thanks

Find your wiring diagram start here:
http://www.volvowiringdiagrams.com/?dir=volvo/S40%20V40%20V50%20Wiring%20Diagrams
No 2005 is there so I looked at the 2004 version you can look for the 2005.
TP3978202 S40 V50 2004 Wiring Diagrams.pdf

The layout is different than the older Volvo wiring diagrams, but you need to
take the time to understand the wealth of info in that manual.
The index and PDF pages are not the same but look around to understand how to
find what you want.
Index is on PDF pg 220
Components PDF pg 222
Component locations are just before the index and not adjacent to the
schematics

Go to PDF page 27 and 28 and look at the items serviced by the two grounds
31/66 and 31/67 (see pdf pg 214) see if there's more things dead such as seat
heaters. You added the power seat which helps understand a pack of things
quitting, The power seat shares the ground 31/66 with the L rear windows.

Just what grounds did you service?

The left pillar B is where I'd start
you can have a loose or corroded crimp connection.
If you suspect a bad connection from 31/66 back to the battery then you can
just hook a jumper cable from the battery negative terminal to the Left B
pillar and see if that fixes things, since there's more connections under
the hood that have to carry high current.

Bill

Thanks,
I checked the battery resting it is 12.7 volts. The batter recently dead because dome light was left on and I recharged, this was a few days before the issue occurred. It is weird that the motors seem to be getting power but will not lower the windows. Maybe there is a voltage draw before the current gets to the motor. I will have the battery tested at an auto supply store today .

Driving through deep water causes all sorts of problems. Water can be splashed on to the serpentine belt causing it to slip, that can cause low alternator output and consequently a low battery supply voltage.

The window motors require at least 12V.

Let the car dry out nicely while you trickle charge the battery overnight. Then try the windows...
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My back feels better when I sit in a Volvo seat