Search the Community

After accelerating in sand up hill my traction control light kicked on, I attempted to override by pushing the TC button and lost all forward motion immediately. Reverse engages and I can also lock 4wd in reverse however no forward gear or forward movement at all. i dropped the transmission plate with no metal shavings and oil looked normal. Next I changed the separator plate with new check balls in the valve body. New filter and fluid with same result…any suggestions I’d appreciate. Not once did I hear any grinding and no codes were given on the dash. All shops want to buy a new transmission rather than trouble shooting. Please help.

My 09 silverado 5.3 4x4 has shifted hard into 2nd and some into 3rd for several years now. A few months ago I decided to fix it. Codes were for transmission control solenoids, module, oil pressure sensor, misfires...etc. codes like P0700 P0717 P0521 P0523. I replaced all 3 shift solenoids, oil pressure sensor, and immediately the truck shifted like new again and it lasted for a few days or a week. And it started shifting hard again. Really hard. It's so frustrating. And it's throwing all the same codes again. Recently, my truck started misfiring so badly the entire truck was shaking. It was running on two cylinders. All of the ignition colis were failing all at once and the truck was not drivable. Btw, I just changed out those ignition coils, plugs and wires just two years ago, all Ac Delco plugs/wires and duralast ignition coils. So anyways, I replaced all of the coils plugs and wires again this week and the engine no longer misfires, running on all cylinders again. And for a few hours after, there was zero hard shifting now. It was running great, like new again. Shifting smooth as could be. But after making it into the city and hitting traffic lights and stop signs, it didn't take long for the very hard shifts to come back. I've read on this and have been dealing with this in time and parts for so long now. I've read about ground wires could be the cause of all of this. I have replaced everything the computer has suggested, and for a short time after the repairs, the truck would run like new. But the hard shift always comes back. I know there's people out there that have had this same problem. I've read a lot about it but without actually finding the grounds for these specific sensors, I've hit a dead end. The issue just keeps coming back as it's obvious there is a root cause I am not getting to. Please share any knowledge or experiences on this topic. And any knowledge of the location of these grounds may be at. Thank you!

Please Help. We're working on a 2001 Chevy Silverado 2500HD.It was stuck in limp mode. We first got the P0783-85 codes, so we replaced both shift solenoids, as well as the wiring harness. Still shot the same codes and was stuck in limp mode. So we replaced the transmission. Still didn't work. Now it's pulling up P1860 and both shift solenoid again. Also I realized it was shooting these codes before I even put it in gear. And that's what makes me think it's the ignition switch. Any help at all will be greatly appreciated and save my sanity.

I have a 2017 GMC Sierra 1500 Denali 6.2L with the 8 speed transmission (73,000 miles). When shifting from park to drive/reverse there is a clunk and also when the truck is accelerating from low RPMs there’s a hard shift from 1-2 & 2-3 gear. I’ve taken it to the dealer multiple times and they “can’t find an issue” with it. Any help would be greatly appreciated! IMG_6286.MOV

Sorry if this seems long winded but I want to provide as much info as possible. Just picked up a 2019 Silverado 1500 custom. Has the 4.3 V6 with the 6 speed transmission (6L80 I believe) The truck had 99 miles on it. Currently around 2500. No issues out of the gate, after about a week of driving I noticed a very delayed shift I think it was from 1-2 or 2-3. The engine revved 1-2k high RPM than normal before shifting. a few days later while on the highway (cruise set at 75mph) out of no where the RPM’s spiked as if it had downshifted. There was no additional load on the engine to cause this, like going up or down a hill. This happened a few times. I called the dealership immediately and brought the truck to them a few hours later. Got a loaner for a few days while they looked over it. They called me to come pick it up, said the tech noticed a little bit of rough shifting and said they “re-set” the shifting points. Since it was an intermittent problem for me I don’t think it arose for them. So I took the truck home, no problems. My wife drove it to work that same night and the same problem happened again. This time the engine light came on. I scanned the codes this morning and the ECM showed P0700 (transmission control system the TCM showed P2714 pressure control solenoid D performance/stuck off. So back to the dealer it goes, waiting for them to bring me a loaner this time. I was was told by a dealer technician that GM has been having them put a different type of transmission fluid in some of these trucks due to issues with the torque converter. But I guess if a solenoid is stuck it could be due to a fluid issue as well? Just speculating. I’m curious if anyone else has had similar issues. I haven’t had much luck finding anyone else online with the same problem. Which is guess is more of the reason I’m posting this, in case there’s someone else lost like myself. I will keep this updated when I get further down the road with the dealership. I get that there are fluke problems that can arise, but this is a bit irritating considering it’s a brand new vehicle. I will say that the dealership I’m working with has been extremely supportive and not trying down play anything I’m complaining about.

I have a 2017 GMC Sierra 1500 Denali 6.2L with the 8 speed transmission (73,000 miles). When shifting from park to drive/reverse there is a clunk and also when the truck is accelerating from low RPMs there’s a hard shift from 1-2 & 2-3 gear. I’ve taken it to the dealer multiple times and they “can’t find an issue” with it. Any help would be greatly appreciated! IMG_6286.MOV

Anyone have a check engine light show up then go away and come back? Code uo129 lost communication with brake control module, UO101 lost communication with transmission Control Module. Went to bed with no check engine light, woke up in the morning for work and noticed the truck would not remote start. When I go in to head to work noticed check engine light. After work ran codes. Shortly after getting codes and using google to research check engine light was gone. Went for a drive never came back on. Woke up this morning it was on again. Can anybody relate?

Recently bought a 2014 Silverado LT w/ 5,3L and 6-speed trans(4wd crew). Truck has 110,000 miles on it, but appears to be lightly used and truely all highway miles. I have been driving it for a week now w/ no issues but this morning on the way to work under light driving the truck jerked and the engine light and the traction control light came on. They went off about a mile down the road but truck now seems to shift hard. Is this a sign of transmission problmes? Should the dealer have been able to see this problem by reading recent codes? I was told there were no issues and the truck had just been scanned and had no codes in the record. Any ideas on the problem? Any comments on if i got screwed by the dealer? Are there issues w/ this transmission? What should i be doing to remedy or extend the life of the trans? Any thoughts would be appreciated. Thanks I have a 2007 that has shifted ereatically from day 1 and now has 180,000 miles without a failure, maybe chevys just shift this way?? ughhh.....

I have a 2004 Chevrolet Silverado 1500 4wd with the 4L60-e 4 speed transmission. Currently I have no speedometer and despite the transmission shifting very well, it skips second gear consistently (no intermittent functioning). This is the ONLY gear that it has issues with (reverse and the rest of the gears are good). Here is the story... I bought this truck being told the transmission was shot. Initially it would not shift past 1st and also had a functioning reverse. I had the tranny swapped with an equivalent from a suburban. It improved slightly but still there is no speedometer or second gear. NO ENGINE CODES have come up throughout this entire time including prior to tranny being swapped (this includes no ABS lights). Here are the different problems I have found on the internet that I have tried to rule out: VSS- A mechanic with a good computer states that all 3 Vehicle Speed Sensors read correct speeds in real time on the road Ignition switch- Already changed Fuses/relays- All appear to be intact and functioning Dash cluster- broken connections fixed restoring all function besides speedometer Transmission treatment- Lucas treatment put in in case this could be a sticky solenoid to no avail Grounds- All appear to be in excellent condition and no frayed wires visible Low Voltage- New battery in place Help me out! What I can see as being my next options are either changing out the ECU or the wiring harness, neither of which I am desiring to do. Any recommendations from your experience that I may have missed in my internet reading?

Story: transmission overheated @ 60k miles. Warranty replaced with new transmission. I’ve had the vehicle (2018 suburban LT 4x4) since new and always sit around 190 degrees give or take and back and fourth around 200 when towing. With the new transmission I keep hitting 210 up to 220 driving around town and not driving hard. I haven’t towed yet but tow often and I am very concerned and afraid to tow. I just finished a thermostat delete to test that out and driving for about 30 min around town and freeway it was over 190 and climbing. It took a while to get there compared to normal but still got hot. Dealership has no clue and the transmission shop has no clue. I need help in figuring out what could be causing the heat. I am so for an oil change and my AC blow nice and cold.

Ok so I have a 2015 gmc sierra 1500. after backing up and putting it into drive I get going for about 5 to 10 seconds ill get a jarring lock up for a split second. First time it happened I was going about 40 and I bounced off the steering wheel and left a little skid mark. It sounds like either my transfer case or transmission is locking up but it literally lasts for a split second then goes away. also I've noticed that after shifting from reverse I hear a loud transmission whine before it does it. This has happened at least 30 times for about a year and dealer says they can't recreate it. It's the 6spd tranny Also I know all about the normal GMC transmission clunk when shifting I have that too but I've learned to live with it. This is something else entirely. Its dangerous and I can't find anything on any forum mentioning this issue

How's it going , new to forum and hoping someone could shed some light. I have a 2019 silverado custom 5.3 w/ 6 speed trans with about 37k. A month ago the truck threw error p0741, it would Rev high and not want to shift so dealer replaced tcm and new fluid. A few weeks past and code comes back with trans temp running around 215* when it did so dealer replaced torque converter and said it was good to go. I took for a extended drive of so.e city and a Lil hwy for around d 1hr and Temps climbed to 225*. Is 225* high? Doesn't seem normal and dealer is saying they. Ant find anything wrong 20210429_195723.heic

I have a 2004 Chevy Astro van 2WD 4.3L with a 4L60E automatic transmission and something is seriously wrong, but I have yet to figure it out. I definitely need some help. I usually do all my own repairs and I am very mechanically inclined, but this has me stumped. I even consulted a friend who knows a lot more than me and he was puzzled and asked that I share with him what was wrong once it has been diagnosed. I would probably be willing to drop the big wad of cash down for parts for a remanufactured transmission if needed, or for a remanufactured rear end and new axles.... BUT the van is not worth spending $1,500 (or more) times TWO. I need to definitively be able diagnose the problem so that I can decide how much I'm going to have to invest to get it going again. I bought it used from a municipal police department that used it as a crime scene investigation vehicle and it has no hitch on it, so to the best of my knowledge it has never done any towing. Here is what happened and what I have checked thus far.... I pulled out of the driveway at work and after I had cleared the 2 lanes of oncoming traffic and was in the crossover in the median I let off of the accelerator and heard a slap, pop, or bang that sounded like it came from the right, rear corner. I instantly thought it might be trouble as it sounded like clapping/slapping two solid bricks together. I hoped it was just something I ran over. Then I pulled out and accelerated up to 55 mph. Then about a 1/2 mile down the road I heard what sounded like driving on a tire that was completely flat. I pulled off the road to check out my tires. I was surprised when they all looked fine. I realized something had to be wrong and I wanted to get my van to a better spot where I could investigate further. I put it in reverse to back up a few feet to better align me with the area I wanted to drive to, but the van would not move backwards. I wondered if something with my rear brakes had broken or locked up. I was able to move forward in D, but there was a good amount of resistance as the engine was struggling to move the van forward. There was a good clear spot nearby where I parked. I thought somehow something had broken in the rear brakes and bound things up preventing the van from moving as normal. I jacked up the van and removed both of the rear wheels, removed the pads & rotors, then propped the calipers out of the way. I put the transmission in neutral. I replaced the rear wheels as it was easier to rotate the tires by hand than trying to rotate the lugs on the hubs by hand. The tires spun freely by hand, but after about 10 revolutions there was a clang noise and the tires stopped. I rotated the tire in the reverse direction and it no longer made the driveshaft move as it had been in the forward direction. Then the clang noise again and the tire stopped rotating in the reverse position. Both front wheels easily rotated when spun by hand, so the binding wasn't coming from the front This made me think that it was possibly something going on in the rear end. I pulled the cover and I saw no obvious problems with the differential. I have the G80 rear end which I had never seen that type of rear end before. When I moved my tire forward by hand slowly there was no movement in the rear end, but when I put my foot on the tire and give it a spin the tire moved a lot and the rear end moves a little. I didn't see anything that looked worn or damaged in the rear end. I cleaned up the parts, cover, and magnet and put the cover on with a new gasket and replaced the fluid. While both the rear wheels were still off the ground I cranked the van. It was still in neutral, but both rear wheels were slowly rotating forward. Then I shifted into Drive and, with the engine idling, the wheels would pulse several rotations forward, then slow to almost a stop and then repeat the pulse & near stop. I couldn't understand why the surge and slow was taking place. Then, I drove it the 1/2 back to work to leave it in their parking lot. The van made all sorts of popping, grinding, and clanging noises. When I stopped I put the transmission in neutral, but it would not roll backwards. I tried reverse and the nose of the van dived down and the rear bucked up, but the van never traveled any distance in reverse. I pulled it forward a few feet into the nearest parking space. The van did throw a MIL code on the way back to work, which was a P0756 (PCM sensed an irregularity in shift solenoid B). I thought that I might need to remove the driveshaft and see if the transmission would turn the output shaft while in reverse. Also, I could try to see if there were and weird noises, pulsing, or resistance to the output shift turning when in Drive. But, I wouldn't necessarily know for sure the tranny was good if it only misbehaved while under a load. I had ordered a set of shop manuals about a week before all this happened, and they have now arrived but I wanted to see if anyone had any ideas about how to diagnose my problem before I resorted to the shop manuals. I get bogged down in them because there is soooo much information in them. How can I definitely determine if the problem is my tranny, my rear end, or both? Here is a video link on YouTube showing when I had the rear end cover removed: Here is a video link showing when the rear end cover and fluid were replaced and both rear wheels were off the ground in Neutral and in Drive with the van running:

Hello all. I own an 18 Silverado 1500 LT , double cab, 6’6” box, 6 spd transmission, I have opted to put 26” status alloy empire wheels with tire size of 305/26/30. Stock transmission gave out. Stock Transmission went out. They said torque converter and pump went out then everything else went with it. Was able to replace the entire unit with a remanufactured from GM. 1 month later, back to the shop (dealer). They covered the repairs because it was under warranty but if it goes out again they won’t because they believe it is the rims causing the trouble. However they will cover if it goes out with stock wheels. Which I will be putting back on. Has anyone else experienced issues with this type of truck and 26” wheels? I did research the “Unsprung weight” makes some sense, however only the transmission gave out, not my drive shaft, drive shaft knuckles, diff, just the goofy transmission which I know the 8 speed has had their share of ongoing things. How is it that a truck that is capable of towing 9k lbs has issues with no load on 26” rims. Pulling a payload in the bed of the truck and pulling a trailer should still have the same effect. If I can’t tow anything with the truck, then what is the point of a truck. I have went back to stock rims to see what would happen. Anyone with info ,thought , something sketched on a cocktail napkin would be greatly appreciated. I do thank you all for your time on this. I have attached the service ticket to this post.

Good day, I have a 2012 GMC Sierra 1500 Z71 4x4 SLT. Latley I have had an issues with the shifting. Most of the time all is good, but when I'm going between 35 and 40 and let off the gas then give it some gas it hits real hard. It does the some what of the same when I am on the highway going about 70 and I give it more gas. On the highway it seems to down shift ( feels like I'm stopping) than shifts hard. The transmission was just rebuilt and I just replaced the tps and cleaned the throttle body. I at a loss and am running out of money to throw at it. The transmission shop ensures me it is not the shift soleniods, he says if it was I would have a lot more shifting issues than I currently have. Also, the check engine light does not come on and there are no codes in the history. Any help would be appreciated

Has anyone ever tried changing the aluminum line to rubber hose crimps for the transmission and oil cooler lines out for AN fittings on and 07-13 Sierra 5.3L? I have a 2013 Sierra and the cold here in Canada isn’t kind to these crimps as I believe the rubber and aluminum have different shrink rates because of difference in material causing them to leak. Replacing them will not solve the problem as the will just do the same thing every year. So what I want to know is if anyone has successfully done this and what fittings did you use?

I've searched pretty much endlessly for some insight into this, and haven't found any good input outside of a lot of arguing. Thought I'd see what you fine folks may recommend here. Have a 2015 with the 6 speed transmission. Just hit 100k. I am the second owner (got at 23k) and to my knowledge has never had a transmission service, diffs, really anything outside of normal oil changes and filter changes. My question is this - what is the current recommend procedure for servicing here (both of transmission and anything else that might be recommended)? Do I do the exchange + filter, or do I do the full flush the dealership is recommending me? From what I've read, the diff fluid is an easy switch so I can do that. I don't rag this truck, don't tow, sometimes have stuff in the bed. Nearly 100% highway miles. Roughly 2300 hours on engine. Transmission stays at 190-192F. Don't have any mechanical issues here, and really nothing outside of a condenser and evap temp censor replacement last year. What else is recommended here? I'm a big dumb idiot and just haven't taken into account the additional 97000 service plan, as I've always heard never to mess with transmission fluid. I want to make sure I get as much as I can out of this truck. I appreciate any feedback/help/advice you may have. Also don't mind a little roasting as I'm sure it's warranted.

I recently bought a great used 2007 Silverado 5.3 2wd with only 78k miles. I seen the carfax that the trans fluid was changed at 15k. So I decided to flush the system. But now I’m nervous that it might’ve been a bad decision and I might have done more damage in the long run. The flush didn’t include a new filter either so I might have it changed. Anyone think it’s going to deteriorate sooner or later?

Just recently bought a 2015 GMC Sierra 1500 SLE 4x4. I am the third owner. Shortly after buying the truck the transmission grenade’d itself. I’m at 97k miles so still under the 100k mike power train warranty, however I was 21 days outside of the 5 year part of the warranty. I reached out to GM after returning from deployment to try and get some help and hope that they would honor all or maybe partial warranty. Needless to say no help from GM! Shopped around for shops to rebuild and ended just buying a remand one for 2.7k. So here are my questions: 1. Flush the current cooler or buy an upgraded one? 2. If I should buy an upgraded one then how big? Also should I bypass the current one in the radiator to have a separate cooling system? 3. I’ve heard of people deleting the transmission oil thermometer to achieve a cooler temp. So say do this because heat is the enemy, others say the trans is built to operate at a certain temp. 3.What temperature is the best operating temperature? 4. Should I have the new transmission re flashed or swap the one from my grenade’d one into the remand one? 5. What’s the best way to flush the current cooler if I don’t change it? I’m afraid if I just try to flush it then it won’t get it clean enough and I’ll mess up the new transmission! That’s all I can think of right now! Thank you in advance for your time and expertise!

I had purchased AMSOIL Signature Series ATF for my 18 Silverado - 6 speed. After having it sit for a while and never getting to a transmission flush on my own time, I called a local, honest, reputable transmission shop near me that has always treated my dad very well. They’re a no-bull, honest shop, and the owner is down to earth and knowledgeable regarding transmissions, as he should be. I informed him I had AMSOIL and wanted it switched with that, and he advised that for the 6L80E, it wasn’t a great idea. He has nothing against a better fluid, but he advised that AMSOIL doesn’t treat the electronics nicely, and it’s a common issue. I’m an AMSOIL guy, and do want him to use the AMSOIL fluid, but has anyone else heard of this or advise to simply use DEXRON VI and NOT AMSOIL?

Question to all new truck buyers who bought a 2018 Chevy Colorado, you having any transmission issues, like slipping between 2nd and 3rd gear on the automatic floor shiftier or problems with the + and - buttons ?

So I have a 2014 Silverado with the 5.3 and if I don't let it idle while fueling I can't start it for atleast 20-30 minutes (whether I put half a tank or full tank) I had the fuel pump changed and that temporarily fixed it for about 3 months. So then I changed the injectors and fuel sensor there was no change and no check engine light. Probably unrelated but its saying gas cap open when its closed and has started messing up on shift points with a weird whine almost like its stuck in tow-haul with an engine brake when I start slowing down. I don't know how else to explain it other than that. Transmission was replaced by dealer at 78K it's sitting at 115K now and if I could I'd drive it off a cliff at this point but SW Texas has no cliffs. I've heard possibly torque converter, whole transmission, or simple computer problem and was wondering what y'all might think. Why I ever switched out of the Duramax and Allison I don't know but lesson learned.

Hi all, I'm new here and hoping y'all will be able to help give me some direction. I have a '15 Yukon XL Denali with the 6 speed MYC transmission and almost 140k miles, my transmission has begun shuddering when I'm driving between 25-35 miles an hour, does not seem to do this at really any other speeds. I spoke with a dealer who said their suggestion is just to go ahead and replace the transmission, this feels a little extreme at this point since Im not having hard shifts etc. I've owned the vehicle for the last year and put about 27k miles on it in a year. I have no records of any previous transmission maintenance and the fluid looked good when we purchased it. I know that dropping the pan is a pain in the neck, but I'm thinking that I need to change the filter since I have no idea how old it is. Husband is out of town and I'm wanting to get this dealt with ASAP. I'm pretty capable of doing a flush or dropping the pan if I have a good write up to follow, so any advice would be much appreciated. Also, what fluid have y'all had good luck with? Thanks, Jenn

4L60-E transmission whining only when vehicle is in motion. Mostly starts past 30mph. Transmission is off the Suburban now. Whining still present when input shaft is turned.

My recently purchased '05 Silverado 1500 has no problem shifting except between 2nd and 3rd. On upshifts, it shifts out of second, then there is a small flare, then it tries to engage 3rd, then it flares again, then it engages 3rd. It takes about a second and it's very consistent. On downshifts, it acts pretty similarly but it essentially acts like it's in neutral for .5 seconds. If I'm in 3rd or 4th and I depress the accelerator, revs out to 4k or 5k and then roughly engages 2nd. Otherwise it's perfect. No slipping, normal shifts, normal idle behavior, reverse works well, no noises or smells. The transmission fluid level and color is fine. I did some googling and narrowed it down to the computer, valve body, or solenoid which is basically not narrowed at all. Has anyone else had and fixed this problem?