I was hunting around for a way to determine when my T/C goes from locked to unlocked when towing (other than watching for the slight tach increase), and knew there had to be a signal to the T/C lockup solenoid. Well, I found
THIS POST at TheDieselStop.com detailing (I mean
really detailing) the addition of an LED. I found the wire in question at connector C172 on the passenger side of the firewall. (Its' a grey connector under under a snap-off plastic cover/metal bracket assy.)
The discussion also gets into adding a T/C lock-up switch, which I think could come in handy as well, but I'm hesitant to install this. I assume Ford knew what they were doing when they programmed the PCM to lock/unlock it under certain conditions (and I don't see any long-term reports on the effects of the manual override switch in the linked post). It would be nice, though, if the trans would downshift directly from OD to 3rd without the "3.5th-gear" slip mode. It might also be nice to get a little dynamic braking?
I'll be adding the LED, but would like to know others' thoughts on the switch.
Andy