Ford Shop Manual describes possible harsh shift concerns with TCC not engaging. My '04 quit locking up 2,000 miles from home, flashing OD OFF light, but shifts were all OK, including shift into OD- (cancelling OD with button dropped to lower gear normally, evident on tachometer).
My code indicated TCC solenoid failure possible. I drove the Explorer all the way home to Missouri with the damn light flashing, eng. RPMs higher than normal when the eng. had to work, like climbing grades, 70 MPH on level about 2400-2800. No doubt used more fuel with TC churning all the time.
Bought a new solenoid block, installed it, trans. back to normal again. I considered, if the solenoid was NOT the cause, and a new TC was called for, just continuing to drive it without the TCC operational. In your case, the harsh shift situation would urge me to go ahead and fix the trans. (soon!).
Just my HO. imp
