When you get an overwing exit door light ON on the P5 overhead panel, it could be the solenoid not working correctly when commanded. Experience showed that the solenoid gets 28VDC when the emergency doors need to be locked, but that the solenoid could be a bit sticky or slow to retract (due to dirt, dust or moisture), causing the warning light on P5 to go ON. Replacing the solenoid solved the problem.
An explanation on how this solenoid moves the lock inside the exit door, is shown in this movie, and on the picture below.
