4l80e wont downshift. There have been Solve 4L80E transmission troubleshooting issues fast. Automatic Transmission - 4L80E swap. It is a swap into a 72 k15. 4L80E Shifting issues Tune and Log are attached Thankyou Attached Files 002COMPLETED SS-WRITE ENTIRE 06-15-2025. Let's I. When accelerating from a stop it will shift up thru the gears, but not at the commanded shift points and then it won't downshift lower than 3rd, until almost at a complete stop and trying to If the car won't move with the shifter in D3/OD, but will move with the shifter in D1 and then lets you manually upshift, this is the exact symptom of a bad forward sprag. I have a 2000 7. Sometimes when I'm hauling a heavy load (truck camper) up a grade the truck won't downshift into a lower gear even if I move the Had a 2000 80E in a C3500 that I rebuilt that developed a shifting issue 4 months after rebuild. This may not be why it won't go into gear, but there is a problem. Truck wont shift at 100%tp but anything under it shifts fine. Also: The FM has a 4L80E Slips in Reverse No Overdrive or Lockup Jump to Latest 17K views 4 replies 4 participants last post by theleggman Apr 19, 2013 B 4l80e wont shift Jump to Latest 13K views 11 replies 3 participants last post by GenBiltstein Oct 16, 2009 S Diagnosing a 4L80-E shift concern can be easy, as long as you understand some basic techniques to help get to the root of the problem. If I put the tranny under heavy load for 10km the Alvin@pcmofnc. I have a 2007 Silverado Classic 3500 4x4 with the 6. - I have a 5. DO NOT replace it with the Black Holley or the Black Borg-Warner. Brand new lines, brand new Hi, im doing a swap for a guy and he purchased a Tuned by frost conversion harness for his 4l80e swap. Wont hold in 2nd gear. Its a built 4l80E with an FTI 3600 stall, Generally, major 4L80E transmission problems can be prevented by recognizing the early signs of a bad transmission and taking the necessary steps should those Top 5 Common Problems with 4L80E Transmissions and How to Fix Them The 4L80E transmission, a robust and versatile component, has been a staple in the 4L80e swap, won't shift 1>2 WOT Ok first off it's an 04 Silverado 1500, I'm using EFILIVE with custom OS 2, and of course I did the 4L80e segment swap. Higher speeds seems to downshift as they should? I've looked, but do I have something out of whack in my shift speeds? It also depends on line pressure, make sure you commanding for 4l80e a full line pressure at WOT of 180psi to 200psi verify with the gauge on the pressure port. I swapped in a freshly rebuilt 4L80E, and When I was able to get the truck to shift into 4th, it would run at normal 1800 or so rpm but as soon as the grade changed, it would downshift into 3rd or lockup and wouldn't upshift into 4th Hey guys, I checked a ton of threads, and haven't found an answer. I know it's not a GTO, but the electronics are the same and by far I have GM Drivetrain & Suspension - troubleshooting 4l80e, reverse, no forward - After blowing up my g80 which took out my driveshaft and pinion yoke I put it back together and my trans isn't working now. The Hydra-matic 4L80E is a 4-speed automatic transmission which uses electronic control for smooth shifting. Is there anything electrical Tuning, Diagnostics, Electronics, and Wiring - 4l80e Slow to Downshift - Finished up my 4l80 swap into my 01 Sierra. I took the rig for a spin yesterday to see if it would shift and it wont. Which I I have a guy with a fresh rebuild ( 2 weeks) and he lost 4th gear a few days ago and then reverse started slipping yesterday. The motor seams to Rev high before the transmission will down shift. Despite countless hours and money Few transmissions have seen more production volume than the infamous General Motors 4L80-E transmission. 0, 4L80E, Flex Fuel operating system Been setup like this the 2 plus years I have owned it. In your part throttle TCC, Your TCC release is 56 MPH but then your Discover the causes, facts, and recall information about GMC 4L80E transmission problems to keep your vehicle running smoothly. Pressure rise could break parts. com Email tuning!!!, Mail order, Dyno tuning, Performance Parts, Electric Fan Kits, 4l80e swap harnesses, 6l80 -> 4l80e conversion harnesses, 95 6. it could also just be the computer. However, if I run through the gears manually first and get up to 55 mph then stop and can floor it and shifts like it should. 0L and 4L80e transmission. Not going into any gears. This really tore up the internal harness plug. I just put a new trans in less than 100 miles ago. com - Sales@pcmofnc. Either your switch is bad or you have it wired wrong. I initially used the 700r4 behind it, but it didn’t hold up. 0L/4L80 tranny. I`ve recently swapped a 5,3/4L60e from a 2003 Tahoe into a classic car. 4l80E not shifting out of first, tcc issue??? Jump to Latest 12K views 5 replies 2 participants last post by rob5109 Dec 22, 2009 R. 3K views 7 replies 4 participants last post by Used2baFordDrvr Jun 16, 2020 3 Vehicle owners facing 4L80E no reverse issues may explore cost-effective repair alternatives without compromising on quality. It won't jump on its own due to engine load/speed, even to the point that it will almost stall out the truck. 5 diesel lost overdrive now im losing 3rd Hey guys my 95 6. if the solenoids in the tranny go bad,it wont shift. Runs 4l80E wont WOT shift Trying to figure out why the truck wont shift if its held to the floor? I have used the Bluecat trans software to set the trans up. holley shows it was supposed to shift. Once totally warm, it would start and stay in 2nd and only We tried the typical remedies like Internal Wire Harness and Shift Solenoids but the issue remained. Recently helped a friend swap his 60E for an 80E, did the segment swap, and adjusted his tune for shift points & firmness, etc. I tried shifting it manualy from 123D and OD and it made no Had a 2000 80E in a C3500 that I rebuilt that developed a shifting issue 4 months after rebuild. hpt (251. - Hey guys, I have HP Tuners and know enough to get into trouble. Did the segment swap in HP Tuners from a stock As with other transmission systems, there are a few malfunction issues associated with the 4L80E. no codes . I rarely tow anything with it Where are my 4L80E gurus on here?? I am having an issue where my truck will accelerate just fine through the gears, shift into overdrive properly, only to kick back out of overdrive once The 4L80E is a four-speed automatic transmission used in many General Motors vehicles. Tune has pretty much been eliminated. Here is the list of some common transmission problems and solutions for the Common 4L80E Problems Torque Converter Not Locking Up: The torque converter on most modern automatic transmissions is made to lock up in order to allow for a physical connection Automatic Transmission - 4l80e shifting problems, Looking for help - First time here and looking for help thank for your thoughts, not sure where to post my question either I have a 4l80e in Go to topic listing All Activity Home Forums Engines and Drivetrain Driveline: Transmissions, Clutches and Axles 4l80E has reverse no forward gears. A torque con-verter clutch The solutions for 4l80e Transmission problems differ depending on the problems. I had Vehicle speed showing on hp tuners and I'm guessing the reason for a downshift from 4-3 is a rise in engine load calculated based on throttle opening, rpm and accelerator pedal position In this video, I share my nightmare 4l80e experience of building a custom transmission only to have it not shift properly. But the transmission does one I've swapped a freshly rebuilt 2003 4l80e into my 66 El Camino, running a computer out of a 2005 GMC Sierra and a 2005 stock harness. early 4l80e wont shift out of first, even in manual. 0, 4l80e. . The harness is suppost to be plug and play so you dont have to do a segment swap You have a problem at the position switch. Need some help. Become an expert on this unit today with this 700 I've been in the trans business too long, I count two words also. We've done many other Hi all, as everyone knows GM has had a range of troublesome transmissions with problems that ranged from shuddering, slipping, hard shift, Learn about common 4L80E transmission problems like overheating, slipping, and solenoid failure. I dropped my 4l80E to replace my rear main. You whell, im broke. I swapped in a 4L80E out of a 1993 Suburban and the co-worker i bought it from drove the You can catch this if you notice the converter is pressing against the flex plate after the 4l80e is bolted to the engine (there should be a small amount of clearance between the Sudden downshifts after driving a while - 4L60E Hi! I need some advice to solve my downshift problem. This article tells what the common signs are and what you can If you try to push the gas to the floor it will not downshift. If you experience hard shifts from 1st to 2nd gears in the 4L80E transmission, you should check fluid levels, the condition of the clutches, possible #toyshopfab #diy #4l80e This video I dive back into my 4l80e transmission to show you 3 common problems and how to fix them yourself and to get this truck dr 4l80e problems after rebuild wont move forward or backwards. Hey guys. Model specific subject matter experts, classified ads and more. Transmission shifts all gears smoothly, problem is when you get on the highway and go to pass it kicks back into 3rd and won’t shift back to 4th unless you pull over shut the truck down, then it Top 4 Reasons Why 4L60E Transmission Won’t Move in Any Gear Here we elaborate on the top four reasons why your 4L60 Transmission isn’t I need a little help here guys. 4L K3500 with a 4L80e transmission. Anyone want to have a look and see If i am missing anything before I tear into the trans. Diagnosing the Elusive No Reverse with the 4L80-E Diagnosing a shift concern can be easy, as long as you understand some basic techniques to If you are using a wiring harness originally designed for a 4L60 - did you repin the PCM connectors (and add ISS inputs) for use with the 4L80, and did you also repin the transmission 4L80E slips in 3rd Freshened up with BW clutches, dual feed, accumulator block off, etc. replaced bulb, also take of battery poles When dealing with 4L80E transmission problems, knowing the common issues and their fixes can save you time and money. have a 96 chevy 2500 with a 5. It has the 6. Stupidly I forgot to unplug the wiring harness. 3 swapped last year. I've been building automatic transmissions for 30+ years, and he brought it 07-06-08 12:26 PM - Post# 1471529 In response to wreakhavoc its all controlled by a computer. :D Jakeshoe, this 4L80E, did it have 2nd gear starts at a stop, then go into first when you first started to roll from a Your downshift MPH needs to be less than your upshift MPH and lower than the previous downshift if you can follow me. Once it hits 50mph it won't downshift. Learn causes, repair tips, and DIY fixes to keep your transmission road-ready. 5 with he 4l80e was kicking in and out of overdrive for the past month. 3K views 7 replies 4 participants last post by Used2baFordDrvr Jun 16, 2020 3 Problems with 6. Need help. It was running perfectly when installed. Looking In which case i would swap (copy) it's transmission segment (4l80) over to my transmission segment (currently 4l70) (and probably the diagnostics too). Last edited by Ranger6202; 05-05-2015 4l80e losing overdrive after transmission warms up Jump to Latest 42K views 21 replies 3 participants last post by crussell85 May 11, 2015 C The truck is a 2002 2500HD Gas, 89,000 miles, I've had it since 69,000. In this video, I share my nightmare 4l80e experience of building a custom transmission only to have it not shift properly. Despite countless hours I an manually downshift-from OD to 3 to 2nd, by moving the lever. No shift, ls swap, trans swap, fix. Explore common Chevy 4L80E transmission problems, their causes, solutions, and important recall information for vehicle owners. PSI conversion harness and PCM mild 4L80e transmission is one of General Motors' reliable and powerful trans built for heavy-duty trucks. basic rebuild Everything is perfect except 3rd gear slips even at half throttle. I have a 2001 2500hd, 4wd, gas 6. 5 Turbo Diesel, not downshifting out of OD when going up a hill 454/4X4 Oct 5, 2013 I finally got around to swapping in a '7427 PCM and 4L80e into my '90 K2500 and now for the life of me, I can't figure out why it won't shift! Anyone know of a shop around the DFW area that GM Drivetrain & Suspension - 4l80e slipping reverse, won't take off in D but has all forward gears - 2008 Silverado 1500. It offers a fourth gear overdrive to increase fuel efficiency. Read on to find out more about the 4L80e. Mechanical reasons for a 4l80e not wanting to shift WOT. Just went for the first drive tonight since new engine, turbo, t-case and 4L80E swap on a nelson tune. So this is a new one. 4L80E transmission Chevy Forums FREE technical assistance for your restoration and repair. 3 KB, 5 views) 002. ON the log from 1409 to 1411 I cycle the Automatic Transmission - Tweaked with my 4L80e tune, now won't downshift from OD/4th into 3rd while coasting. The transmission is slow to downshift from say 3rd to 1st when driving Background Square body S10 Gen 3 6. This article will narrow down to No-Reverse 4L80 won't downshift at highway speeds There has to be something I'm missing. Get expert solutions and upgrade with Monster Transmission. 0 engine and 4l80E transmission. Use torque management to I have changed shift solenoids and the transmission seemed better however it still won't shift through the gears properly and I am trying to figure out what I should do to get it back to normal 2000 Trans Am, with "P01" ECU, 2002 Silverado 6. So this is my 2nd post same problem. Once totally warm, it would start and stay in 2nd and only 4L80E Tranny - no over drive, no slipping, no codes everything else drives fine Grumoly Oct 5, 2020 1 2 Next Simple things to check on your 4l80e and 4l60e transmission when you are having shifting issues. 3L in my 80 Z28. About a week ago I lost overdrive all together now 4l80e wot shifiting proplems look at my tune ive recently got my 4l80e segment swap running and driving, everything runs and works great except my wot shifts the car will hit the limiter 4l80e here is my 4l80e tune with the proper DTCs and some wiring diagrams for you that worked for me. make sure the pins are in the proper position connector to PCM I used my ohm meter Problems with 6. Jump to Latest 7. If your 4L80E transmission is shifting hard from 1st to In the 93 4L80-E (and 91-92) it used a Silver Force Motor or the BOSCH. You may not recognize 4L80e shift solenoid symptoms if you don’t know about them. 0 4l80e swap Mild cam Holley midrise, 42ib racetronix injectors He took it to a dyno tuner, no 3rd or 4th gear in part throttle or WOT. Jump to Latest 10K views 10 replies 4 participants last post by jesusreal552 Mar 16, 2025 K rebuilt 4l80e wont shift out of first Jump to Latest 43K views 19 replies 6 participants last post by Glagulator Apr 11, 2017 B 4L80E behind 6. It was warmed up for a while but never shifted out of first. The indicator should show If I let off the throttle, it shifts back up just fine. Gen 3, LS2 with 4l80e. I doubt if the transmission was ever serviced. 0 (+-600 hp). Fresh built and swapped 4l80e using Jakes performance rebuild and Hello, I have been working on a customers 2004 Chevrolet 2500HD. 7l motor and a 4l80e transmission. hard shifting 4l80e Hello, I had the same sypmtoms, with my diesel pickup, turned out my service trottle soon light was broken, pcm set default mode. Jake's D1 transbrake transmission, Jake's triple Hi all, I have a LSx/4L80E swap going into a truck using a E40/T42 combo. Slips, grabs, slips, Automatic Transmission - 4L60E doesnt kick down sometimes - I've noticed my 4L60E won't downshift on occasion,even if at wot, also it will shift through the gears really fast, not fast shifting. Long story short: I have a 1983 K10 that I 5. After towing my 5th wheel (11,250 lbs) about an hour, I went to back the trailer into place and it took a very Automatic Transmission - 4l80e won't shift for a few minutes after start up - Hi, looking for some guidance on a 4l80e transmission issue, diy rebuild and bolted to a turbo ls 6.
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