i've been having this problem for a few months now with no change. whenever i let off the go pedal, in 4th gear, it downshifts. it seems to do this once warm or after the truck has been driven then shutdown and restarted, but sometimes it happens from the start of the day. it also seems to stay in gear as long as my foot is pressing down slightly, just don't let off. i put in new batteries, apps, cleaned grounds, changed filter/fluid, i changed the valvebody (stuck throttle valve) before prob existed, maybe a month before. the solenoids have been changed. it will not hold fourth. there doesn't seem to be anything else wrong. i've been around the internet and back. using dial-up internet i live in the stix and need that o\d. should i be looking for a new tranny this one works good aside from this. truck is a 01 24v

 

Strange! Never read or heard about that scenario!
How many miles on her? New Factory valve body or....?
Does your OD "Lock Out" dash light work? IF so I assume it does not come on when it downshifts? In other words it is a downshift... not a lockout of OD?
You said "changed solenoids (plural)..... so you changed the Transducer (pressure sensor) as well as the Govenor Solinoid?
If "yes" and "yes" to above....sounds like an Overdrive unit problem.....maybe OD clutch slippage or a seal leak allowing pressure/torque load reduction when you back off throttle .

Just guessing!

RJ

 

maybe 150 000 miles, i think its at 275 000 km. it's just like someone pressing the o/d button while in fourth but the light doesn't come on. and the light does work and i did mean solenoid/transducer. the vb was a reman. from a semi local shop. i did pull the speed sensor in the o/d and some fluid poured out, not sure if it should be in there. i'm leaning towards vb or o/d section. the two worst case scenarios. at this point i would welcome it being electrical cause i just don't feel like learning any more tranny stuff.