Fishnchipy

Hi folks, new to the forum here and this is my first post. Lets see if I can get some love with this one.


I have a 97 Cavalier Z24 with a 2.4L and a 4T40E 4 speed tranny. My issue is I am getting ETS and check engine lights and a code of P0742. When this happens the tranny goes from working perfectly to short shifting 1-2 and then 2 to 3 and immediately to 4 basically skipping 3rd. It chugs when it goes into 2nd since it does it so soon and bogs when in 4th because again it does it to soon.


I can manually shift it at around 3000rpm and it runs fine through all 4 gears even with the lights on. I can hook up to my code reader and erase the code and it goes back to running/shifting perfectly. I can reproduce the issue every time I climb a hill and put the engine under a load. I must do this with a slow and steady acceleration up the hill so the tranny will not downshift. While under this load boom, lights come on and issue returns. If I accelerate rapidly and the tranny down shifts, no issue.


I live in CA and climb the Grapevine which is a 3000' climb and that's when it first happened. I have tested and/or replaced all the sensors but the EGR Valve and Speed Sensor. I have a vacuum hand pump to test the MAP and it was good. I manually tested the TPS and got a steady rise in Volts (.4 - 4.5). I added some MAF sensor cleaner in a vacuum line while running and got a .8 volt reading on the O2 sensors. If cam and crank sensors are unplugged the engine dies so I assume they work.


The car has only 114,000 on it and the engine was rebuilt last year due to a head issue and only has 14,000 on it. The original tranny was just replaced with this one from a wreaking yard because the original was constantly locking and unlocking the torque converter, buzzing when warm, and it had metal in the pan.


The junk yard tranny was in great shape but I still installed all new solenoids and a pressure manifold plus new filter and fluid obviously. I am open to all suggestions at this point!

Exgie

The error is for the converter circuit stuck on.

Fishnchipy

I am aware of what the code is for. My question is what sensors control the lock/unlock of the torque converter. I know its not stuck on because when I hit the brake it unlocks and the RPMs go up. What controls the locking and unlocking so I can get it to unlock under a load?