Recently i started having some problems with my monte shifting very hard while i was driving. When i checked the car out at the time, the radiator fluid was low. So i Flushed it throughly and refilled it with the DEX-COOL fluid that the vehicle came with when i bought it a year ago. All was fine. Though i thought! A few weeks later the vehicle started to act up again, doing the same thing as b4. So i checked everything again. This time the fluids where at there normal levels. Once i finished checking everything, i started the car back up and drove it around. Too my surprise, the problem seemed to go away. I started monitoring the temperature guage in the car while i was driving around, and noticed that it was getting slightly high. Not high enough to cause an alarm, but noticed it was staying slightly higher than i had noticed b4. Keep in mind that when i flushed the system b4, i changed the thermostat as well. Then the strangest thing started happening. It recently started getting a little cold here, and im have to turn the heater on to warmup. I noticed that the drivers side climate doesnt blow hot air. Only cold air no matter what. The passenger side blows as it should and adjusts to the proper climate that i choose. After riding around for awhile with heater on, i notice the vehicle starts shifting hard again. I then turn off the AC completely. It still shifts hard. I then stop the vehicle turn the car off. Since the there is a doom light delay upon exiting the vehicle, i then open the door and close it to rest everything, and wait for the headlights to go out. Once the headlights go out i start the car back up and start driving. The car is back too shifting normal now. Since i've noitced that it happens when i have the AC or HEATER on, i have been drinving around with none of that on now and the car drives fine. But i still notice that the temp guage is still showing the car getting hot. On top of that, i notice that b4 ALL of this started, i use to be able to hear the cooling fans running even when i was standing outside the car. Now i notice that i can barely hear them at all. And when it does come on, BOTH fans come on for about a couple of seconds and then go off. I've sat there and watched them come on and they come on. I dont know what else too do. PLEASE HELP!!!!

 

I am also having the hard shift problem. I have just changed out my thermostat as well. I don't believe that these are related though. I have not noticed higher than usual temps. I was thinking about getting the PCM tested, but is there a way to do that with hitting the dealership?

Anyone had this hard shift problem resolved?

 

Unfortunately I cannot help with this problem, just wanted to let you guys know that I too experience the "hard shift" but I have not noticed that it is related to the AC. I have noticed, however, that when it starts to shift hard, it does not stop doing so until I turn the ignition off and restart the car. Does this sound familiar to you guys?

 

YEP!!!! And thats exactly how i get mine to stop hard shifting. Turning the key off..

 

Think ive figured out the problem. But dont hold me too it. Check your fans with the A/C off completely. Let the car get warm and check then check the fans. Do both fans come on? Im not sure about this but it seems a little weird too me. One fan is for the A/C and the other is the engine fan. Without the A/C running, there should only be one fan running i think. it should be VERY PRESENT that it is on, even with the hood closed and you standing outside the car. If you cant hear them, and when you check too see if they are on, both will be running. What i think is happening, that transmission fluid is getting hot because the fans arent cooling properly. Again, im not sure about this and im doing every sort of check possible to prove my theory. The reason the car starts shifting hard is that one of the sensor is registering a HIGH TEMP alert. It wont appear on the dash mainly because whatever sensoring is controlling the trannys temp is set to alot lower temp than the thermostat for the radiator. Thats why if you look at the guage on the dash, the temp reads normal. Now check your tranny fluid. When you do this, take the dip stick for it out and clean it. Do you see any BLACK residue there on the rag or paper towel that you used to clean it? What is that you say?...Thats the tranny fluid breaking down. Basically, the fluid is getting TOO HOT and breaking down, just like motor oil does. The reason for the HARD SHIFTING is due too the high temp sensor triggering the computer in the car and putting the car in what is commonly known as LIMP MODE. Basically, it allows the car to still be driven in that mode until you can safely get too somewhere to have it fixed. The HARD SHIFTING is result of that, basically to protect the engine, etc, from getting damaged, but shoulnt be driven for an extended period of time. If you check your owners manual for your car, it mentions such a mode but doesnt go into great detail about it. Turning the car off resets that sensor IMMEDIATLY, thus resulting in the engine shifting normally like it should unitil it registers a HIGH TEMP too the computer and, well you know what going to happen AGAIN! Too make a long story short as of now, the problem could be few things: the radiator fans or even a bad sensor and or possibly the ground for the fans being weak somehow. In my case, i have ruled out the bad ground. So the only other two things to check is the sensors and possibly changing the radiator fan assembly. Again, dont hold me too this. It merely at this time is an observation through the simple testing and that i have done. I will keep you posted with my findings as i go along.

 

I have my $$$$ on the temp sensor...

 

im thinking the same thing you are! Are there more than one temp sensor? Are you talking the about the one right by the thermostat?

 

If I am not mistaken, there are two, one you mentioned and one in the block. I would pull codes to find out exactly though...

 

I just posted the same question. I haven't noticed a connection to the heat and a/c. I haven't heard about the tranny temp sensor. But I just got off the phone with a service guy at gm. I described the clunky shifts and a whining noise that associates itself now with the noise. He said that it could be a something sticking in the valve body or the pressure control solenoid needing replaced. This could cause the tranny to run at a higher pressure and thus the whining noise. This is an expensive replacement cost. So, I am very interested in whether or not anybody else has come across this and actually made the repair and if it fixed the problem.

 

If you dont mind, do you have a number for the that person that you talked too. I would really like to talk to him about my situation also and see if he thinks its the same. I also ruled out myself that the A/C has anything to do with it. Last nite it started doing the HARD SHIFTING without the A/C or heater being on at all. I drove for about 2 hours straight b4 it started shifting hard. I have change the temp sensor on the engine, located right by the thermostat 2day. I will let you know what happens 2morrow.......