Rear wiper motor - Always low power

[sk_mountaineer]

2005 Mercury Mountaineer:

Weird problem - My rear wiper motor tries to move when I push the switch, but it doesn't seem to have power to move the wiper completely. If I hold the wiper off the glass, it usually moves most of the way. Once I put the wiper blade back on the glass, it gets stuck.

I replaced the rear wiper motor myself several times: Once from a junk yard replacement, once a rebuild, and finally supposedly a new one from the dealer. However, I still have the same problem, so I don't think it the wiper motor itself anymore.

Do I need a new rear wiper motor, or is it a relay issue, or something else? I didn't think it was a relay issue since the motor tries to move.

Thanks!

 

[boominXplorer]

Swap the relay with a known good one to eliminate that as a possible issue. The relay contacts could be weak inside. I'm not positive but I think the relay for it is behind the right rear plastic panel inside the truck, basically behind the right rear taillight inside the truck.

 

[firecat5]

Is the relay a common problem ? mine does the same thing, and has run the battery down twice because it will stay on until the arm returns to the down position, even when the the truck is turned off.