4t60e problems lost of 4th gear od at cruise

[tony94gtp]

posted a few times in this section never got any real answers to my problem. So i will try again the problem that iam having is the lost of 4th gear at cruise speed lost of tc lock up my ecm code p0740 tcc switch.now my car doesnt stall when come to a complete stop and if i do the key off key on quickly trick 4th gear and tc lockup will be ok for awhile i have changed fluid and filter doesnt help. could the vac mod be bad? what about engine timing would that play a part in how the trans act ? all other gear shifts fine just once i get up to cruise speed 45-55mph 4th gear drops out. and it seems to do it more in day then at night thats why fluid and filter change figure it was getting hot. may be there are some other sensors that effect the tcc. vss, cam, crank. i dont know that why iam here looking for help before i spend hard earn money at some shop on something i can do myself ijust need to know what to look for. please someone who nows of this problem and has fixed it themselfs please give me some advise

[geoffinbc]

Oh god tranny problems are the worst.

It could be something stupid like a stuck ball valve or check ball. Or it ould be a sensor. Do you have access to a scan tool?

[SappySE107]

Our 95 cutlass doesn't have 4th gear at all. Wish I knew for sure what the problem is but im clueless on transmissions.

[bszopi]

Mine did the exact same thing during the 03 (??) 60V6 meet. But by the time I got back, it did it maybe a couple more times and has yet to come back. I never figured out what it was. I know it wasn't fluid or filter related though, because I had just changed both.

[Rhedalert]

my 4T60E just recently wanted to hold onto 1st gear forever, and didn't upshift until I let off the gas. Happened one day, never happened again. But for near 130,000 miles even if it blew up tomorrow, I wouldn't feel too bad.

[sharkey]

ive come across the falling out of 4th gear problem before, but i cant remember what it is. i know it is 100% an internal tranny problem.

as for the hanging on to 1st, do you have use of a scan tool??? is it setting a code??? if the ecm comands a shift and doesnt see that it happoened, it should get a gear ratio error code.

[Rhedalert]

ive come across the falling out of 4th gear problem before, but i cant remember what it is. i know it is 100% an internal tranny problem.

as for the hanging on to 1st, do you have use of a scan tool??? is it setting a code??? if the ecm comands a shift and doesnt see that it happoened, it should get a gear ratio error code.

I do have access to a scan tool at work, but it's OBD1.5 which usually won't set a code unless it happens for a longer period of time or happens frequently. No SES light came on when it happened. Think it's worth it to scan anyway?

[torq455]

OKKK!!!! P0740 is torque converter clutch solenoid circuit - electrical
-DTC P0740 stores in PCM memory
-Inhibit TCC
-Inhibit 4th gear in hot mode
YES, i have a service manual!! This is called the defalult action. I'm going to see if I can get the trouble shooting page on here.

[sharkey]

before you get happy that you found its an electrical or solonoid problem, im gonna burst your bubble.

code P0740, tcc solonoid circuit, this code is set when the pcm doesnt detect that the vehicle has gone into lockup. there can be several things that cause this. it could be wiring, it could be oil leaking through the case connector and cauing a bad conection on the pins (unlikly, but possible). it could be a stuck lockup solonoid, however not a common problem. more likley though its a stuck lockup valve, or you tcc clutch is smoked out. in either case, there is a reason for it. if the valve is stuck, there has to be something, usualy a metal fragment or partical of clutch thats caused it to stick. if the lockup clutch is brunt up, its not as simple as removing the tranny and replacing the converter. all that clutch material has gotten inside the tranny, and throughout it, and will cause issues.

[torq455]

nooooooo way am i saying that was the prob. just a place to start. trannys suck trying to trouble shoot even if you have some knowledge. what fun!

[sharkey]

i fully agree with you. transmisssion codes dont tell you much, at least not untill you find the proper info on what they mean. many times they point you to an internal problem, and at that point, you pul the tranny out and go through it.

[SHOoff]

ive come across the falling out of 4th gear problem before, but i cant remember what it is. i know it is 100% an internal tranny problem.

as for the hanging on to 1st, do you have use of a scan tool??? is it setting a code??? if the ecm comands a shift and doesnt see that it happoened, it should get a gear ratio error code.

I dunno about the 4t60E, but my Toronado had the older 440t4. It wouldnt hit 4th gear (and if it did it took forever) but it had a TSB out on it for "late or no upshift". And you could feel that the throttle valve inside the tranny was jammed. Being electronic I dont know what the 4t60E has, but i'm sure there's something electronicly activated to command a downshift at WOT.