younkin1

OK guy's, here is my problem- I just bought a 2007 Express 3500 cargo with the 6.0 and the 4l80E transmission. It has about 230000 miles on it and I just had the transmission rebuilt because the fluid was badly burnt and it was slipping in 3rd and 4th gears. We installed the rebuilt tranny and now I have a shifting problem. I'll do my best to describe it. When starting from a stop the transmission seems to feel like it drops out of gear for a couple of milliseconds and then goes back into gear. It seems like the trans is trying to go into 2nd gear but then snaps back into 1st kind of harshly. Maybe the words stutter or stumble would best describe it. The transmission shift great after that. It only happen when starting from a stop. It never sets a code. It seems to be worse after the transmission warms up. It won't do it in direct 1 or direct 2, but does it in 3 or 4. Fluid condition is great no smells or discoloration. We check the operating pressure and everything in within specs. We've had the valve body down 3 times, replaced the shift solenoids, checked voltages, double and triple check everything including the wiring hardness (internal & external) and found nothing. We just removed the tranny and torn it down and inspected everything and found nothing. Has anyone else had a similar problem? One more thing and this may not have any correlation, but I believe it may. When servicing the engine I tried to reset the oil service light using the KOEO, throttle pedal to the floor within 5 second sequence as designed. But the ECM will not respond to it, so I'm unable to reset the oil light... Most mechanics know about the problems a faulty TPS (the old 3-lead) can have on a transmissions shift points. This van has a drive by wire throttle set up that I'm not familliar with. Does anyone think maybe it could be the TPS or the floor pedal potentiometer? Do you think there could be a correlation? I need help in a bad way- Thanks Guy's

canucklehead

I don't have an answer, but mine does a similar thing on occasion. Its like the tourque converter is not engaging the tranny on slow acceleration, but when you give it more gas it bumps into gear and goes. I am not certain it is the tranny at all in my case. I just live with it since its rare.
My tranny was rebuilt before I bought the van....

Brok

If it is a rebuilt transmission. Is it the ORIGINAL rebuilt or a ORDERED rebuilt transmission. Your gear ration could be off if it is for the PCM. The other possibilities but it sounds like you know about rebuilding transmissions if it's dropping off pressure at your accumulator or servos feeding your 1-2 shift. The other question I could ask is if you have checked the Input Shafts, sun gear shafts, splines, check ***** or anything else that could cost hard shifting. See how it works in reverse as well. I mean I could name a few possibilities but I would need more information on the issue. I really doubt it be your throttle position sensor as that influences nothing that your describing.

younkin1

@Canucklehead- I'll keep you updated about the repairs, Thanks

younkin1

@Brok- We rebuilt the original transmission. Operating pressures are with in specs. Did full disassembly and inspected everthing, and all is good. We're going to reassemble it and install it. We're going to drive it with a break-out box next. Also it doesn't do it in reverse. If you can think of something else please let me know, thanks.

Brok

A no reverse. Yes I can post a few things for you on that which can cause that problem since that is more isolated.
If there are conditions for High/Low pressure, check the possible diagnostic trouble set.
If there is a damaged or missing cushion spring or retainer, then reverse the servo assembly. (reverse servo)
If there is a damaged seal or piston or misassembled servo, then reverse the servo
If there are damaged or broked drive link chain or damaged sprockets, check the drive link assembly and replace or adjust as necessary. (Chains should be pretty tight not loose to the valve edge)
If there are burned or missing clutch plates, damaged piston or seals, leaking housing checkball assembly, damaged input shaft, or blocked feed passages on the input shaft, check the input shaft, check the input clutch assembly and replace and adjust as needed.
If there is an improper sun gear assembly or damaged sprag, check and input the sprag and sun gear assembly as needed.
If there are damaged pinions, internal gear or sun gear, input carrier and reaction carrier assembly as necessary
If the oil pump assembly slide is stuck, the seals damaged, the vanes damaged or the pump drive damaged, the oil pump assembly should be checked.
If there is a burned or damaged reverse band or band apply pin is mislocated, check the reverse band assembly and replace as needed.
If the 1-2 shift solenoid or torque converter clutch solenoid has malfunctioned or walked out, check the 1-2 shift solenoid valve or torque converter clutch solenoid valve and replace as necessary.
If there are damaged splines, check the reverse reaction drum

Jay Michaels

Hello folks: I have a 2001 Chevy Express 3500 (357, 5.7L) with a 4l80e Transmission in it. I just LOST my reverse two days ago while on a trip. It still drives FORWARD, however, it drives forward even while in Neutral (it appears to be in drive when in neutral). The ONLY way I can move the vehicle backwards is by turning off the vehicle and slipping it into reverse then pushing. This can not be accomplished while the vehicle is running. I am at a loss. Each shop I go to tells me something different. "Selenoid" "Torque Converter" "New Tranny" and so on....I sure could use some insight here as I am 1200 miles from home. Thanks

ray caldwell

Silly question,but you did use a new torque converter right? Also,some trans filters slip down at times. I put a slim magnet under filter and installed drain plug. Other than that have the controller checked out

mountainmanjoe

@ray caldwell

he posted that 7 years ago. He hasn't visited the forum since.

ray caldwell

Didn't know,just got email from forum on weekend.