5906 sound activation button problems

Reverse wire polarity on the bell controller. Looks like the controller is wired in series with the center rail.  On a KW the common goes to the outer rail I think it is marked U.

Dale H

The two U terminals in the center of the terminal cluster are common and are bussed together as well.  The A and B terminals at the bottom are the center track connections for the two handles.

2356,

  Dale is absolutely correct, the Controller is wired in series with the center rail on the old KW's,  simply reverse the polarity of the bell controller and it will activate

the newer engines horn & bell correctly.  gunrunners knowledge is spot on also,

I often install Banana Plugs or cover the mid terminals because if the wire from the outer terminals touch them, the track control wires can be fried quickly.  It's one of the reasons I put banana plug couplings on my old KW's outer posts.

PCRR/Dave 

Mid transformer is the KW with Banana Plug couplings that keep the running wire completely away from the mid terminals.

I reversed the wiring on the button controller and once again the button now controls the horn and the kw's horn lever turns the bell on and off.  Any ideas how to get the button to control the bell and the lever on the kw to control the horn, or do I have to live with it working backwards from what it is supposed to be?

Sure, wire the A or B terminals of the KW to the center rail and the U post to the outside as it should be, and the whistle control on the KW will control the whistle as it should.  For the button, wire it in the opposite direction to change the whistle or bell activation.

I have the center rail wired to the A terminal on the KW. I have the inner rail wired to the U terminal.  At another connector on the Fastrack I have the5906's ground wire connected to the center rail and the positive wire from the push button connected to the inner rail.  Both positives to the inner rail and both negatives to the center rail.  With this set up I get the horn to blow from the KW's switch. I get nothing from the 5906 push button when it is pushed.  I put a meter on the leads from the 5906 and the voltage drops about 1 volt when the button is pushed.  To my brain if I reverse the leads of the 5906 I would be creating a short. Its ground lead wire would be attached to the inner rail and its positive lead would be attached to the center rail.  Where am I going wrong?

If you remove the button and wire the KW directly to the track, does the whistle work correctly?  If not, there's an issue with the KW.

With the button removed the horn sounds without any problems. Even with the button wired separtly the horn works ok, just the bell does not work. If I remove the separate power connection from the transformer and only get the track power from going through the 5906 then the bell rings from the kw horn lever.

If reversing the 5906 doesn't solve the problem, my guess would be that it has a problem.