TH 400 help

[lux]

My TH400 is not kicking down.
I have a Lokar kickdown switch all set up correctly.
- I tested for 12 volts at the trans kick down connector. I put my volt meter on the spade and had my wife push the gas peddle down. At about 3/4 throttle I see 12 volts at the trans kick down spade.
- I then tested to see if I could hear the solenoid in the trans. I ran a wire from the battery to the trans kick down spade, When I made contact I could hear the solenoid in the trans. I did it that way so I could eliminate all other noise.

When I'm driving and in 3rd, I go to wide open throttle and it does not kick down to 2nd.

The trans is new but I bought it second hand so I don't know if it's modified.

Thanks for any help.