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I have a 2000 model old style Chevy 3/4 ton with 350 engine and 4l80E transmission. Truck has 80K and transmission was serviced at 60K by GM dealer.
My transmission works properly in all gears on level roads. On a hill it will kick out of OD, it will not shift back to OD when the road levels out. When this happens, the shifts from 1 to 2 to 3 are harsh or jerky shifts not as normal. I can turn engine off for 15 seconds, then restart engine and transmission works fine, until I get to the next hill.
Have had codes checked by local auto parts stores, not GM dealership, but so far no defect codes are noted, also no engine service light has come on.
Could this be the cause of my transmission OD problem?
To prevent the OD from burning out (from constant 3-OD up and downshifting and straining the OD) when towing something under load, the trans will force itself out of OD into 3rd when it detects that the converter is not locking up, The factory converter has an internal clutch that controls the lockup of the torque converter, and this clutch's torque capacity is minimal. Hence, if the clutch is going bad, just the weight of the truck and torque required to pull it will force the TCC to unlock the converter and a downshift to 3rd will occur. It will soon be time to replace the converter.
Note: DTC 83 - Torque Converter Clutch
Problem is a busted piston in torque converter.
Hard to believe this transmission would go out for that at 80K. I would have thought that the 4L80E was a stronger transmission. As this one has been service properly and never used to pull over 6000# and did that rarely.
Just my luck to buy a truck with weak transmission.
Guess I will look at the Dodge diesel with manual transmission next time.
Fred, 1st check your brake light switch. If the switch is out of adjustment or going bad and makes contact, it will unlock the torque. The trans will not stay in overdrive if the torque will not lock. It's the first thing we used to check on an overdrive problem and the simplest to fix. Rich
Hello, I have a 95 G3500 GMC and I have the same problem. I found that the throttle position sensor (on the side of my injector pump) is the possible problem along with the computer going into limp mode when I floor the pedal for passing speed. All I do is sycle the ignition switch three times and it resets the computer and the shift problem goes away until If I only press the pedal 3/4 of the way to the floor it seems to be ok. I haven't tried another TPS because it cost a hundred bucks and I'm not sure if it will cure the problem. As long as I know what to do to keep it shifting i'm going to leave it that way. Gil
I HAVE A 96 CAD.deville with a fwd 4l80e trans it went bad i bought a replacement for it. it still dont work. a frend told me i got a bad one so it was replaced again. the car still dont move any ideas???
Just purchased '03 Yukon XL 3/4 ton - 67,000 mi - 6L engine 4L80e trans - 4wd: On a straight & level freeway @ hiway speeds the TC will suddenly unlock - stay unlocked for a few miles then lockup again. It has done this 3 times in 50 miles. No error codes set. Salesman says this is "normal". What's going on?
Hi can somebody help please.
I have a 1994 fleetwood fair and the 4l80e goes into O/D but not lock up as when I touch the brake at running speed the revs do not increase and the fuel econ is bad.
Sincererly Murray Frater
Exact same issue....replaced all speed sensors, shift sensors, tcc sensor, throttle position sensor, had the trans flushed and new filters with no improvement. Some times it will go 150 miles of interstate driving in OD and then drop out all of a sudden, especially when I have to hit the brake and then resume cruise control. My local dealer just wants to put a transmission in it but I have taken this truck from Maine to Florida and back with no issue (except the OD shift which we are discussing. If it is as simple as a brake light switch I will be happy and yet angry at the same time for wasting all my time and money.
I have a suberban 3500 with 4l60e transmission and i have aproblem in shifting so when i stop after driving about 10 miles and start driving again the transmission shift hardly in all speeds.
I have a 91 C3500 dually with 7.4 and 4L80E. On a flat and level road about 65+ mph the Converter will momentarily kick out and right back in. There's no check engine light and no pattern. I replaced the TPS for a former prob lem and this problem started up. Any suggestions?? Thanks.
I too began havin trouble with my torque converter locking and unlocking erratic shifts and i too have felt the burning of my face as my tuck would kick into limp mode right in the middle of a seldom thought out showing off..i even lost some of my hair...no jokes. why because i installed a k@n filter and opened up those tiny little slits in the upper intake, it baffled me for some time but became clear after i installed a 10k resistor and pot betweenon the harness to the map sensor.. as far as i can tell this is what happened the increased airflow into the motor due to better breathing tripped my map sensor into telling the computer to de-fuel or go into limp mode because of to much boost 6psi instead of 4 ooooooooooonoooooo anyway this also affects the torque converter since it's also electronically controlled and since i tricked my map sensor with the 10k resistor and pot my tranny also mysteriously was cured hope this helps.
Torque Converter lockup problem finally went away-----I hope!! I replaced the throttle position sensor that I had installed earlier and so far it hasn't kicked in and out of converter lockup. Evidently the first one I bought was defective....who knows. It never showed a check engine light.
I have 93 chevy 3500 with 6.5turbo and just put in a used 4l80e the old one went out and this one will go threw all the gears perfict but lock up most of the time kicks in and out.what do you suggest and if no fix can i unhook the lock up.
Have 4L80E in 2006 2500 with 57,000mi. has all four gears but no lockup Has code Po894 slipping components will turn on chek engine light after a while. can clear the code and will shift gears normally but no lockup and after a 5 to 10 mile drive will shift hard but stll no lockup.
I have a 2007 2500 gmc van 4l80e transmission and it comes in hard after 10 miles than it shift hard and once i stop for 15 mins or so it shifts fine for ten miles
email Fred T. Hart Jr.
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