Hi guys, first post here. I purchased this car for my son last year. I rebuilt the motor due to blown head gasket and it only had 100k on it. Got it up and running and had the tranny serviced. Since then new TPS, crank, cam, oil sensors, plugs, injectors, coil cover, boots, struts, brakes, and AC. The car has been like new for him. Recently the tranny has had the torque converter locking and unlocking going down the highway. This only seems to happen in 4th gear and at highway speeds. The car now has 113k since the tranny was serviced. I've checked brake switches and did my best to check the harness. I've researched other posts on here but no real answers other than cutting the tan wire. I'd like to have this fixed the correct way. No codes for the tranny are present. It did throw a MAP low voltage code last week but I erased it and it has yet to return. New battery and alt is putting out a steady 14.1V. HELP!!!!!

Tranny shop had it a couple days and they can not figure it out either. They are leaning towards a ECM issue since the tranny is computer controlled. They ran the scanner on it and no codes. They dropped the pan and no metal. They did not charge me at least and I got a fluid change out of the deal. I ordered a reprogrammed ECM Saturday so when it gets here I will try that. If that does not work I guess its time to drop the tranny down and open up the side cover. I will replace all 4 solenoids and perhaps the harness since it will be open. I read somewhere that the pressure control solenoid can cause the winding sound (bad power steering pump type sound) I am hearing. This sound only starts when it warms up. Once the sound starts that's when the issue starts. When its cold the thing runs great. This is what is leaning me away from bad pump bearings. If it were bearings wouldn't it buzz all the time? Any input would be appreciated!

Mike Kochanski wrote:Tranny shop had it a couple days and they can not figure it out either. They are leaning towards a ECM issue since the tranny is computer controlled. They ran the scanner on it and no codes. They dropped the pan and no metal. They did not charge me at least and I got a fluid change out of the deal. I ordered a reprogrammed ECM Saturday so when it gets here I will try that. If that does not work I guess its time to drop the tranny down and open up the side cover. I will replace all 4 solenoids and perhaps the harness since it will be open. I read somewhere that the pressure control solenoid can cause the winding sound (bad power steering pump type sound) I am hearing. This sound only starts when it warms up. Once the sound starts that's when the issue starts. When its cold the thing runs great. This is what is leaning me away from bad pump bearings. If it were bearings wouldn't it buzz all the time? Any input would be appreciated!

That winning could could be torque converter shutter. I would change the fluid and filter again... Are you sure it isn't low on fluid? I would check the IAT sensor, and make sure it is reading around the correct air temperature. The IAT controls alot of the settings in a 4T40E. Shift firmness and Lockup are tied into it as well.

Does it act up in reverse at all?






PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

It was actually about 3 quarts over full when it first started acting up. I put it up on stands, warmed it up, pulled the plug on the passenger side while running and in park and drained it out. When I took it back to the tranny shop they said it was still about 1/2 a quart over full. I told them they were last to service it and I had already drained about 3 out of it. I have not checked it since they dropped the pan last week. I am assuming they got it correct this time. The IAT sensor is about the only one I have yet to replace. I will give that a try while we wait for the ECM. Reverse is fine. No slippage in any gear. One thing I did notice is when I put it 1st it still goes up through the gears. If I put it in second it holds 1st and shifts to 2nd and stays there but when I let off the gas it surges back and forth. Ideas on that????

If the trans was that over filled it is probably toast, and needs to be rebuilt...

The 4T40E and 4T45Es do NOT like to be overfilled. I assume a bunch of things could be messed up now.

Like: the pistons, seals, valves...normally.




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

also, could be this...
http://www.transmissionpartsusa.com/4T40E_PWM_down_shift_solenoid_1995_on_4T80E_TCC_p/440-000044390.htm




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

My intentions are to try the ECM, if that does not work then pull off the side cover and replace the harness and all 4 solenoids. Hopefully it does the trick or else its a swap out for a new one.

The strange thing is why does it only do it when it warms up. I would think that if the tranny was bad it would do it as soon as you start it. Hopefully its an electrical issue and the ECM or solenoids fix the issue. I will keep you informed.

I'm beating you have one or more bad solenoids. They commonly act up after hot. If you didn't blow any seals you, hopefully didn't hurt anything else.




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

ECM and IAT sensor did nothing. I guess its time to crack it open and replace all the solenoids.

Well, it took only three hours to crack the side cover open and swap out new solenoids and get it back on the road. The tranny definitely shifts a bit harder but the issue continues. It warms up, something starts buzzing and the tranny cant figure out how to stay in lock or unlock. You can really feel it now that the solenoids have been swapped out. I put it in first step on the brake and give it gas and no slipping yet when I take off and it hits second it feels as if it misfiring and it jerks. If I put it in first and take off it still shift into second then surges like it wants to go back down to first. I go to second and it continued to surge. I go to third and no issue other than the buzzing. I hit fourth and its fine except for the TC locking and unlocking. Now do I buy a remanufactured for $1,000 or roll the dice for a junk yard tranny for $250????? Already dumped $120 for solenoids, $70 for ECM, $70 for power steering, $10 for IAT sensor and tons of time trying to figure this damn thing out.

If you put it in first it should not go into second. It should bounce off the limiter.

This is sounding more like an electrical problem.






PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

Could it be the Neutral Safety Switch / Range Sensor? Thats about the only part I have not replaced.

Dropped that sucker out tonight in 2 1/2 hours wit the boy. Not too bad. The fluid that spilled from the passenger side and cooling lines were loaded with super fine metal flakes. I don\'t know how the tranny shop missed that. Maybe they know they screwed up and over filled it when they serviced it last year. I am pretty sure its toasted. I will remove the new solenoids and go junk yard shopping in the morning. Not the best option but running low on funds now. $400 is easier on me than $1300 right now. I will keep you informed. One thing I did notice while online shopping was the two different 4T40E transmissions. 23mm without a rubber spacer and 32mm with, or something to that effect. I had no idea there were tow. When I removed the cooling lines tonight there was a rubber spacer on the top line about an inch thick. I assume I have the 23mm w/spacer tranny?

Well, I went to a local junk yard today and was able to locate a transmission out of a 96 cavalier for $295 out the door. Thing looks really clean so we install it in about 4 hours and behold it runs fine. I believe Enforcer was correct when he stated the overfilled transmission was the cursor to all my problems. Add another $120 for fluid, seals, and filter. Let\'s hope it holds together for me.

Glad to hear it worked out.




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

Here we go again!
New/old tranny now shifts hard from 1st to 2nd, then when it goes 2nd to 3rd, it immediately goes into 4th (OD) and is sluggish. If I am light on the throttle when it shifts to 2nd, it chugs until the rpms come up. I threw a code of P0742 "Torque Converter Circuit Stuck On". When we put this tranny in I installed brand new solenoids and pressure manifold. If I run it through the gears manually it runs perfect. The torque converter has no issues. This leads me to believe its not in the tranny but in the electrical system. I reset and cleared the code and it ran just fine until I had to slow for traffic and when I slowly accelerated and it was under a bit of a load in OD the lights "ETS OFF & CHECK ENGINE" came on and it started shifting jacked up again. We have two ECMs and they both do the same thing. When reset and no lights, it runs fine, under a bit of a load in OD and the lights come on and shifting goes to hell.
Any Ideas?

I would find a new engine harness....




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

Did some more digging around and tested the MAP and TPS today. Both are good. Harness is in good shape. Now check this out, I erase the code and all is great. I take it for a ride and all is great. I intentionally take it up a hill and put my foot in it and all is great. I go back and do it again but this time I SLOWLY accelerate (maintaining 55-65) as I climb this hill until I'm almost full throttle by the time I get to the top and it does not down shift but the ETS and check engine lights come back on and the shifting from 2nd to 4th upon take off return. I pull over, erase the code and all is great again. I know its not in the tranny because its works just fine until the lights come on and even better when manually shifting it. I'm leaning towards and emission sensor of some sort that sends info to the computer and tells it when to down shift when under a load. I have tested and/or replaced all but EGR, Speed Sensor and Cam Sensor. Car dies when I disconnect Cam Sensor so I assume it works. I roll down the road and hit brakes and the TC unlocks so I know its not stuck like the code (p0742) says.