I have a '98 1/2 2500 24 valve. A few weeks ago it started cycling in and out of overdrive at about 40 mph. I did the APPS reset procedure and the shifting was fine for a while. Yesterday the same thing happened again, but part of the time it would lock in 2nd gear when starting out from a stop. Sometimes I could shift to neutral and restart the engine and it will shift right. I 'm doing the APPS thing again now, but I don't think it will help for long, if it will help at all. I would appreciate any advise you guys can give!!!!!!

Sorry I didn't realize I was in HELP!! forum until it was too late.

 

Any codes? If I remember right cycle the key 3 times and then leave it in run and either then check engine light will flash or the odometer will display any codes. Another thing to look at is tranny fluid condition. It sounds almost like the tranny is going into limp in mode which could be caused by any number of things. The most common failures being the gov. pressure sensor/solonoid.

 

Key forward trick does not work on trucks lower than 2000 I believe, or its 2002. Might want to try and get a scanner on there and see what is going on!

 

Just for giggles, if you haven't done it in awhile, try cleaning the battery terminals and cable ends (both Pos & Neg) on both batteries.

The tranny electronics are very finicky about wavering voltages.

 

... and the ground connector below the passenger side battery!

 

you can buy a electrical noise filter & solder it in at the jtec computer & have no more problems

 

Wrap the positive alternator cable with tin foil. Not fancy, but don't short out terminal. It this fixes, you have electrical noise issues, which require better shielding and noise filters.