Hello my friend has a 2000 Chevy suburban 5.3 liter 4 wheel drive that has an automatic transmission that is not shifting properly it will not go into third or fourth gear most times and when it does go into third and 4th gear it goes back into second gear again this is a consistent problem and I am unable to go more than 30 mph it will keep jumping down transmission fluid is full and has. has anyone else had this problem and if so could you please provide a solution
Sounds like your clutches are worn and slipping. You didn’t post mileage but I’m guessing 150k or more. You should pull the pan, save the fluid from the pan, clean the pan out and replace the filter. Strain what fluid you could save and add it back minus a quart. Add a bottle of Lucas transmission stabilizer. See if that helps. It is a giant bandaid to help with slipping. Longterm your probably looking at needing a transmission. If rest of the vehicle is in good shape being 4 wheel drive it is worth doing. You can have a mechanic hookup a diagnostic tool and check your shift solenoids but the fact it does shift and then downshift tells me your clutches are worn and slipping.
3rd and 4th are usually the first gears to go out on those transmissions at 150k.
Try Thumpy's advice and you might get lucky.
