TC Manual Lockup Not Working
 

First off, my TCC is not locking at all. It seems to try to lock ever so slightly at part throttle (RPMs drop a bit, then return - either TCC trying to lock or compressor surge?).

It has tripped a code (O/D light blinking), but I was unable to check it and the last trip I made I didn't notice this behavior at all (didn't seem to attempt to lock).

I wired up a basic TC lockup switch (grounding the purple/yellow trans wire), but it has no effect. Measuring the voltage at the purple/yellow wire gives me .07 volts (with key on). Does this voltage seem appropriate for this PCM pin (I assumed it would be ~5v, but IDK).

Could it be that my TCC lockup selenoid needs replacement?

BTW, I was told the trans was "built" (I bought the truck a couple months ago) - it does shift nice and firm.