1993 80 Series A442F Stuck in Overdrive When in "D" (4 Viewers)

[Fzj80 1997]

LAST UPDATE TO THIS… HOPEFULLY…

My buddy just came over and we swapped TCM’s. The truck drives perfectly and shifts through all the gears now. The TCM I swapped in must have been completely dead. Took the cover off the original TCM the board is crisped up in this spot.

 

[Kernal]

So looks like a bad capacitor, IIRC that's been discussed way in the past. Don't toss that board, someone with experience repairing circuit boards should be able to replace the capacitor and repair the trace if damaged.

Complete trivia but a similar example: when a Maytag washer took a dump after an electrical storm I pulled the circuit board from behind the dials (there's a big circuit board back there, who knew), and sent it off to a 80+ year old electronics tech from East Germany (living in Washington State) who diagnosed the problem, replaced a few diodes and Triacs with better specs than the original components, repaired a trace (thin metallic line on the board) and shipped it back to me for under $50! That was maybe 12 years ago but still a good deal (new boards at the time were $350 but would come with the same weaker original components). That washer is still humming along. FWIW

Glad you figured it out.

 

[Fzj80 1997]

This was on the circuit board out of the 94 that I swapped in originally. The exterior of these TCM’s look mint with no surface rust.

 

[Kernal]

I'm not a electronic tech but a good one could find the defective component (even if it looked OK) by testing the specs for each component. The hard part today is finding a tech who will do that for a reasonable cost. I got lucky finding a highly experienced tech who knew how to diagnose and rebuild circuit boards.

Either way, hold onto those boards, someday it might be worthwhile to have them checked/rebuilt.