Transmission stopped shifting and then the engine stalled. After cooling off for two hours, it ran great again. Recent tune up and oil change.

Conditions:Very hot day, stop and go traffic, engine temp very high, a/c running on high, transporting a heavy load.

Is this a possible sensor of some type needing replacement?

 

Depending on just how hot the engine got, the system is designed to prevent a sort of meltdown and tries to prevent self destruction.
When possible in heavy traffic it helps to rev up the engine in neutral to increase cooling and get rid of some of the excess heat.

 

Thanks. That makes sense, the engine was nearing the red line on the temp gauge. Does this also cause the transmission to stop shifting? I'd skimmed another thread that mentioned a bad sensor at the time of the incident, but cannot find the thread now.

 

The worst enemy of an automatic trans is heat !
Safeguards are built into systems to increase circulation and decrease heat generation . That could be why the trans was prevented from going into a higher gear.

 

Thanks for the advice! Makes sense.

 

So, I think heat is not the only problem. Yesterday the transmission died again, refusing to shift. Driving conditions were normal. At this point I suspect it's a bad solenoid of some type, so I'm going to replace the solenoid pack and see if that fixes the problem.

 

Can you be a little more specific as to just what is happening when you say it won't shift?
Do the other gears work, will it start in second gear if you use D2?
Does it just never shift out of 1st?

Since you are planning to replace the solenoid pack , you will most likely change the fluid and filter and that may help.

 

It feels like it's stuck in 3rd, definitely not starting in 1st from a dead stop and feels like 3rd at 35 or 40 mph. I could manually shift to 1st and second or at least I did once.

 

Sounds like you could be on the right path. Suggest checking all plugs and connections for corrosion while you are in there.