Hey guys so I have the craziest problem and I cannot find any answers all over the Internet I can find similar problems in this forum but nothing quite as particular as mine so I have a 1988 Ford bronco XLT with a 5.8 L 351 Windsor and AC six automatic transmission. The problem I’m having is when the truck goes to shift from second gear to third gear. What it does is the truck will stay in second gear and it will not even attempt to go into third gear I have power and increase speed in second gear so I know that it is not slipping but for whatever reason it just will not even try to shift into third. If I manually go through the gears on the shifter I can sometimes get it to go into third but only to do this I have to be driving down the road put the truck in neutral and rev the RPMs above 3500 and then shifted into drive then sometimes I can get the truck to shift into third. Now here is where the weird part is once I do this the truck has no problem shifting into third and downshifting in and out of second and third for the rest of the drive, but if I turn the truck off or put it in park at all I’m back to the drawing board with my problem until I do the neutral rpm shift again. I’ve changed fluid and checked levels replace the vacuum modulator and adjusted it counterclockwise and I really don’t know what to do. I’ve read things about downshift linkage and things of that nature but this truck does not have a carburetor so I’m not entirely sure if that would help also I think it should be noted that when I do successfully get it to start shifting into third it shifts beautifully you wouldn’t be able to tell that shifting if you were sitting in the truck at all so I don’t think there’s anything wrong with the transmission itself. Thank you for any and all help

 

Normally that means the tranny needs rebuilt.

 

If it isn't a vacuum leak, it would have to be valve body.

 

Could be a few things, valve body issues with the accumulator piston or the governor on the tail shaft is stuck or plugged. Either way you are digging into this transmission.

 

In L or manual low,the forward clutch and the low reverse band is engaged. In D,only the forward clutch is engaged when in low gear. If everything else is OK,in my opinion,the forward clutch is slipping and on it's way out.