Not sure but my 98 Town and Country did that last winter, turned out that my Trans fluid was extremely low because of a leak. Once i filled it to the proper level and and made sure it remained full, no problems. It still leaks slowly and i still have to make sure its filled. Beats a new transmission. sucks for the environment though, leaking and all.
If your car has an automatic transmission, there will be a short dipstick near the front (radiator side) of the transmission. With the transmission warmed up (go for a short drive), park on a level surface, and with the transmission in park or neutral and engine running, pull the dipstick out and check the fluid level against the markings on the dipstick.
Does the torque converter lock? It should lock on both 3rd and 4th gear. How are the engine temperature and temp gauge? The 4T60-E requires decent temp information to run normally, othw it goes to "limp mode" and will not engage 4th nor lock. T
Try draining the oil after the engine has warmed up first.
Mine is between 500 and 600 rpm's after the engine is warmed up.
Needs a new thermostat
Trans fluid is always checked with car level and idling while warmed up.
Assuming you have an automatic transmission, the dipstick should be located toward the rear of the engine on the passenger side. With vehicle warmed up and parking brake applied the transmission fluid is checked with the transmission in neutral.
you fill it through the dipstick tube, get a funnel and pour away until the dipstick reads full with the engine in park and warmed up and running.
Are you sure that it's third it's not shifting into, and not fourth? The transmission is designed to not permit shifts into fourth (overdrive) until the engine and transmission have warmed up a bit.
Transmission is not shifting when car is warmed up.
Yes, check it on a level surface with the engine running and the gear shift selector in neutral or park. Check it after the engine has warmed up.
The transmission may not shift or engage in forward or reverse until the car warmed up for a few reasons. Two examples of why the transmission will not engage is low or no fluid levels or a leak.