Thanks Tony. I figured it was a thermal fuse, and showing open, shorted it to try it. The circuit lead to the u controller so I figure it was only a signal. The unit then powered up with an error so it is normally open I guess. There is no band or markings to indicate polarity so I don't think it is a diode. Regardless, the battery charger is in such rough shape it is not worth any more time. Lots of signs of water damage on circuit board and a fair amount of smt components that I am not set up to work with. I recall something about what you said but would not have come up with that possibility. Thanks. I am on to other projects