126 trans won't downshift

[126nut]

On my 89 420,

Out on the road at speed if I floor the gas it just won't go into passing gear, or downshift. The carpet is not bunched up around the switch or anything, I can hear the switch click quite clearly. I did some diagnosis which I learned on my 450SL but am not sure if it applies to the 420SEL. Ignition on, engine off, depress the accelerator fully and listened for the downshift solenoid click, never heard it. Checked for voltage at the downshift switch harness and found none at either pin, the solenoid is supplied by a simple 12 volts, correct?

Need some help please, the 420 is not exactly a speed demon and without a passing gear it is much worse.

A certain Lexus GS400 is calling,,, did I say that??