Why is my GMC transmission not shifting properly?

Most GMC transmission problems such as harsh shifting, delayed shifting, no gear, stuck in gear, no reverse or drive are quite often caused by low transmission fluid level. If your GMC vehicle with automatic transmission is not shifting properly, check the transmission fluid first.

What are the problems with a GMC 6 speed transmission?

Incorrect gear shifts, gear slipping or overheating. Newer GMC trucks equipped with a 6-speed 6L80 transmission can suffer from various intermittent or constant transmission issues. Symptoms include harsh or delayed shifting, inability to engage certain gears, and slipping when shifting gears.

Why does my car not shift into third gear?

Such a problem is automatic transmission won’t shift into 3rd gear. The transmission shifts into the first and then to second gear but does not move into the third gear. It seems that the gear slips into neutral when you push it to the third. Another instance could be the automatic transmission won’t shift into 3rd gear at all.

How to fix a GMC Sierra 1500 transmission?

Yes that’s has happen to two of my 93 Chevy Silverado 4×4 , 1 and 2 fine then free wheel in overdrive. Just change 1-2 – 3-4 solenoids first and if that doesn’t work change the computer per Ebay it’s the cheapest. Hope this helps JJD 36 people found this helpful. My buddy changed his distributor and cured the tranny problems.

When does a GMC 3500 shift into fourth gear?

During the fourth clutch piston stroke, the transmission shifts into fourth gear. – Third Clutch Accumulator: 3RD CL fluid pressure is also applied to the third clutch accumulator which is encased in the accumulator housing.

What causes transmission fluid to be discolored and hard shifting?

Transmission Fluid: You have to check the transmission fluid. Once the transmission is low on fluid, or once the fluid is discolored and old, it could be due to hard shifting. This hard shifting can happen due to a lack of lubrication in the transmission. This fluid must be reddish in color and also should be mostly transparent.

What can cause a car to shift hard?

Disconnected, clogged or bent vacuum lines could affect the pressure in the transmission and might lead to rough shifting. Sensor Problems: These days, vehicles are equipped with a wide assortment of sensorsthat include those which control when and how the transmission of the car shifts.

What causes harsh shifting from 1st to 2nd gear?

Worn Torque Converter Clutch (TCC) regulator valve will cause harsh shifting from 1st to 2nd gear. This will trigger a check engine light and may also trigger fault code P1870 code. The regulator valve is inside the valve body, and there are numerous rebuild kits with upgraded components.

What causes harsh shifting in an automatic transmission?

Please try again later. Jim Markle, the Transmission Doctor, explores the causes of harsh shifting in automatic transmissions. Often, the problem is due to a worn-out solenoid in the valve body, which is inexpensive to replace. Early diagnosis is important to avoid gear train damage and major repairs. Loading…

What should I do if my transmission is wearing out?

Check your fluid level often to make sure it’s at the full mark to keep your transmission cool and properly lubricated. Besides keeping a full fluid level, avoiding shifts at heavy throttle or shifting while your vehicle is moving can help your transmission from wearing out prematurely.

Why is my Trans bad on my 4L60E?

Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the transmission goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either.

What are the signs of a transmission problem?

Harsh Shifting. One of the first signs of transmission problems is when your transmission shifts hard. When your transmission slams into gear it can be a sign of abnormal pressures, worn components or even a low fluid level.

What to do if your GMC Sierra has transmission problems?

The transmission fluid was drained and flushed, the filter changed, and a new transmission fluid added. Was told to drive for 300 miles and if problem returns, I would need a new torque converter. The truck is fine so far (but I have only had it back from the dealer 2 days).

What kind of transmission does a GMC Sierra 1500 have?

355-horsepower 5.3L V8 8-speed shiftable automatic 4WD w/low range Transmission was shuddering at highway speeds under light throttle application. The dealer seemed to know of this problem. The transmission fluid was drained and flushed, the filter changed, and a new transmission fluid added.

Why is my GMC Sierra 1500 not shifting?

Service 4-Wheel Drive light came on, would not shift out of 4WD. Scan found code B272508 (Mode Switch signal). Transfer case switch on dash had internal fault and was replaced. Software update for PCM/TCM and a lubrication of the slip-yolk. This was to fix rough transmission shifting when slowing to a stop.

Can a Chevy Silverado shift from 2nd to 3rd?

No 1st or 4th, shift 2nd to 3rd by itself when put in D or OD and locks converter: Goes into gear but sluggish like brakes are on, can manually shift to 2nd to get moving, then put in OD and truck shift 3rd as well as 4th are OK. Also, torque convertor locks up.

What causes an automatic transmission to not go into reverse?

In an automatic transmission, these units function as a one-way clutch. When the clutches begin to fail, the lower gears will not engage. Repair requires replacing the torque convertor and flushing the transmission fluid. A worn reverse gear can also occur when a transmission is mishandled.

Are there any problems with the GMC 4 speed transmission?

GMC vehicles with a 4-speed automatic 4L60E or 4L65E transmission can have intermittent or constant problems with selecting reverse. This will manifest itself as an inability to engage reverse gear while there are no issues with the engagement of other gears. There will be no other symptoms. The worn or faulty servo engages the reverse gear.

How to know if your Chevy Silverado has transmission problems?

No 1st or 4th gear (torque converter doesn’t lock, can be driven in 2nd, 3rd, and Reverse gear): 1 Transmission is in “limp home” mode or lost electrical power. 2 Check the under-hood fuse that powers the transmission. If it’s tripped, look for a short. 3 If in “limp home” mode, look for PCM codes to trigger this fault condition.

Can a Chevy Silverado go in reverse FWD?

FWD gears work fine. will go in reverse once in awhile. removed transmission pan changed filter and chevy silverado No reverse in truck. FWD gears work fine. Vocational, Technical or Tra… Vocational, Technical or Tra…

Why is the transfer case not shifting in my Ford 4×4?

These motors do malfunction on occasion and are the most common cause of the transfer case not shifting. The relay modules behind the dash also malfunction and will sometimes melt the harness connector at the yellow and orange wires that feed the shift motor.

How does a transfer case shift motor work?

Then the clutch coil is deenergized and the transfer case shift motor engages, moving the shift forks to the desired position. This is done to accelerate the front halfshafts to equal the speed of the wheels and to initiate locking of the front hubs.

What causes a car to have a hard shift?

Causes of rough shifting include: Transmission Fluid Low or Poor Condition – Vehicles low on transmission fluid or that are operating with worn out or contaminated fluid are likely to experience hard shift conditions. Lack of adequate lubrication within the transmission can cause several problems, including hard shifting.

Why is transmission shifting hard from 1st to 2nd ND?

When anyone of this sensors is bad it hard to shift gear. So if the sensors fail to receive and send the right signal readings, shifting problems can occur due to the wrong signal transmission. Transmission shifting hard from 1st to 2 nd could be as a result of an issue in the vehicle vacuum lines.

Why is it so hard to shift gears?

The automatic shifter has numerous sensors that regulator when and how the transmission changes gears. When anyone of this sensors is bad it hard to shift gear. So if the sensors fail to receive and send the right signal readings, shifting problems can occur due to the wrong signal transmission.

Why does my GMC TRA not go into gear?

If there is an issue with either of these the vehicle may experience problems shifting or transferring power to the wheels. If these are not the problem then it could be possible that the transmission is having internal faults, perhaps a worn torque converter, or transmission gears, inside of the transmission.

What does it mean when transmission runs only in 2nd gear?

Transmission runs only in 2nd gear. This is known as running in LIMP IN MODE. The most important thing to remember, when trying to decide if you have a solenoid issue or internal transmission damage (causing the transmission to stay in Limp-In mode) is two very important things:

Why is my GMC Yukon not shifting into 3rd gear?

Driving at speed and the transmission suddenly started slipping while in OD – engine RPMs started racing, pulled to the side and dropped speed. 1st and 2nd gear are fine, but the tranny won’t shift into 3rd. Pulled off at the next exit, found a quick lube station, the tranny fluid (which had about 25 K miles on it) was scorched.

Are there transmission problems in GMC Yukon XL?

Took the truck to an independent mechanic who specializes in transmissions and performance shop work. Upon disassembly, he found the 3 / 4 drum was burnt up. According to him, everything else in the tranny looked “pristine” – no dirt, sludge, or signs of wear or abuse.

How big is the transmission shaft on a Chevy?

The latest generation 4l60-E transmission has three cast aluminum alloy parts: hood, main body, and rear cover. GM reduced the package to 21.9″ long, equivalent to a 15.4″ manual transmission. The input shaft has 30 slots.

What kind of transmission does a Chevy Tahoe use?

The 4L60-E is found in nearly every GM rear-wheel-drive application, including the C/K Truck, Sonoma, Jimmy, Tahoe, Yukon, Astro, Safari, Suburban, Bravada, Firebird, Camaro and Corvette Before the Late 4L60-E transmission, there was the Turbo 700R, which was introduced in 1982.

When did the GM 4L60 E transmission come out?

The 4L60-E is the “E”lectronically shift controlled version of the 4L60. The Late 4L60-E was released in 1997 in and fully phased into wide use through GM by 1998 in both RWD car platforms (including the C6 Corvette) and trucks in both 2wd and 4wd configurations.

What kind of transmission does a 1994 GMC Sierra have?

I’ve got a 1994 GMC Sierra 4X4 5.7 I purchased from an older couple. It has been sitting a year. She said years ago they had tranny trouble; it would stay in low.

Can a 3rd and 4th gears work on a GMC Sierra?

3rd & 4th gears would work sometimes, other times not. You checked all the wiring, pins and plugs and all look good. You put in a used vacuum control module and that didn’t change anything.

Why is my 4L60E not shifting into 4th gear?

Below are some common things that fail in the 4L60E and cause this problem. It probably goes without saying, but if you put the vehicle into second gear manually, you’ll still be able to get to where you need to go. If you end up with a bad sprag, the 4L60E won’t be able to shift into 3rd or 4th gear.

Why is my GMC Sierra not shifting past 2nd?

No change then changed transmission. Still same thing that black plastic box on the side was cracked I just changed it still nothing. One fella said maybe change get out that cluster that plugs into the box. I’m at end of my rope. It’s Christmas and im getting really bummed where is there a fuse or relay if anybody can help please. Kathy in tx

Why does my transmission rpm keep climbing up?

It seems that the gears are slipping and causing the rpm’s to climb up. Check the transmission fluid and make sure that it’s full and red in color. Very dark red or black transmission fluid is an indication that the transmission is burning the fluid for getting too hot from either overloading or slipping gears.

What causes the gears to slip in a car?

Low transmission fluid will cause the transmission to slip the gears. If the fluid is good and the transmission has been serviced before, then the clutches inside the transmission are slipping and it will need either rebuilt or replaced.

What happens if the transmission is overfilled with fluid?

The transmission is vented so that pressure won’t build in the unpressurized areas. Transmission fluid can leak out these vents if it is too high. The seals higher in the transmission may also leak, but these seals are not pressurized.

What causes transmission fluid to leak from vent?

Leaking Fluid. Overfilling the transmission fluid will not cause seals to break, but they may leak. The transmission is vented so that pressure won’t build in the unpressurized areas. Transmission fluid can leak out these vents if it is too high. The seals higher in the transmission may also leak, but these seals are not pressurized.

What happens if you have too much fluid in your transmission?

In the long run this can lead to heavy wear on your gearbox. Since automatic transmissions rely on fluid to function, too much fluid in the transmission will result in irregular shifting. This can lead either to early shifting or to delayed shifting with jerking. The transmission can also make strange noises.

What happens when you overfill a transmission clutch?

Because of the foaming and very little room for air, the excessive transmission fluid would overheat the transmission instead of keeping it cool, and without room for air, depressing the clutch would result in fluid trying to ooze out of the transmission, compromising the sealing in the process.

How to fix delayed shifting on a Chevy Silverado?

Car goes into gear but feels very sluggish like the brakes are dragging, but it will roll easily (starts out in 4th gear), you manually shift to 2 to get it moving, once it’s moving you put it back in OD and the car shifts 3rd to 4th on its own and locks the converter at the appropriate time: ShiftB solenoid failed: Easy fix in the pan.

What’s the difference between delayed shift and harsh shift?

4. 1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace. 5. Trans does not upshift out of first, speedometer reads zero at all times: VSS failure.

How to change Hard Shift on 2004 Silverado?

Install the gray (Circuit 23) wire of the vehicle wiring harness into cavity “C” of the new 4-way connector. Obtain a piece of 0.80 mm/18GA black wire, 254 mm (8 in) long.

What causes transmission to shift from first to second gear?

Some customers may comment that the transmission slips, a shudder, chuggle, or vibration is felt when the transmission shifts from first to second gear. A 12 Hz electrical feedback from the charging circuit may be affecting the transmission pressure control solenoid, causing a fluctuation of the line pressure within the transmission.

How to avoid hard shift on YouTube 4L60E?

4L60E Transmission Hard Shift? Check This first! – YouTube 4L60E Transmission Hard Shift? Check This first! If playback doesn’t begin shortly, try restarting your device. Videos you watch may be added to the TV’s watch history and influence TV recommendations. To avoid this, cancel and sign in to YouTube on your computer.

What causes a 1-2 shift flare on a Silverado?

Some customers may comment about a 1-2 shift flare with an end bump or a harsh 1-2 shift at light throttle. This condition may be caused by the 2-4 band apply time extending through the 1-2 accumulator stroke. 1. Verify the customer’s concern. 2. Remove the valve body. Refer to Valve Body and Pressure Switch Removal in SI.

What are the most common problems with a GMC Sierra?

Another 258 people reported the second-biggest issue where heating and air conditioning temperature and air delivery mode door actuators may fail. If one or more delivery mode door actuators fail, the HVAC system may not produce correct temperatures or air delivery. The HVAC system stores fault codes, which help with diagnosis.

Why is my shift gauge not working on my Chevy Silverado?

Gauges that are not working could mean a faulty ignition switch. This has been an issue on this truck series. A bad ignition means that there may not be full voltage available to activate the shift solenoids. Replacing the switch will cure the problem. Figure 1. Look for blown fuses or damaged wiring.

What happens when you have a bad Shift Solenoid?

Erratic shifting or shift slippage: The shift solenoids regulate the flow of hydraulic fluid for shifting. A problem with one or more of the solenoids can cause a lack of pressure, resulting in hard, soft or delayed shifts.

Are there transmission problems in my 2004 GMC Sierra?

Now, these trucks are getting older, and it’s very likely that your 2004 Sierra may be having transmission problems. Below, you’ll find a ton of troubleshooting your transmission problems.

Can a 4L80E Trans shift in reverse?

I’ve got a 1992 chevy 2500 4×4 6.5TD/4L80E 3.42 gear The trans shifts great in all forward gears, no codes, and locks up the torque converter as it should. no slipping whatsoever. When put in reverse it clunks like its engaging, then won’t move, no sign of moving. It clunks like its in, but 100% freewheels.

Now, these trucks are getting older, and it’s very likely that your 2004 Sierra may be having transmission problems. Below, you’ll find a ton of troubleshooting your transmission problems.

Why is there no reverse on my Chevy Silverado?

It sounds like it’s time for a diagnosis from a transmission shop or a GM specialist. The only way to really know is to scan the transmission for codes to see if a solenoid has failed, though, I have seen GM truck transmissions lose reverse as a sign that it needs some work or repair, several times.

What causes no reverse on GMC Sierra 4L60E?

No Reverse – Most of the time reverse won’t engage when the clutches are worn out. It may be (but is less likely) that the sun shell went bad as well. There’s a whole article on this site dedicated to diagnosing no reverse in the 4L60E. It is pretty applicable to the 4L80E as well.

What kind of transmission does a GMC Sierra have?

The 2004 GMC Sierra was the 6th year of the GMT800 platform truck. Now, these trucks are getting older, and it’s very likely that your 2004 Sierra may be having transmission problems. Below, you’ll find a ton of troubleshooting your transmission problems. The 2004 Sierra was a carryover from the 2003 model year.

Why does my Chevy transmission not go into 3rd gear?

Chevy transmission won’t shift, stuck in 1st gear or limp mode – Speedometer may also display zero at all times. It could be internal transmission failure, low transmission fluid, or faulty Vehicle Speed Sensor (VSS sensor). Chevy transmission won’t go into 3rd or 4th gear – This is a good indication that 3 or 4 gear clutches are worn.

What kind of transmission problem does a Chevrolet have?

Newer Chevrolet cars, equipped with a 6-speed 6L80 transmission, can experience sporadic or constant transmission issues. This ranges from harsh or slow shifting, failure to engage any gears, or gear slipping. In some cases, it may even cause transmission overheating.

Why does my GMC transmission not go into gear?

Transmission will not go into gear when warmed up gears t… I put Lucas in the transmission because it was low on transmission fluid and was slipping in over drive then it stopped working at all after I put Lucas in it but when I first start it will go into gear and work fine until I get up the street then lose all gears how can I fix this

I’ve got a 1994 GMC Sierra 4X4 5.7 I purchased from an older couple. It has been sitting a year. She said years ago they had tranny trouble; it would stay in low.

What to do if your truck doesn’t shift into overdrive?

Turn the engine off and let it cool. Then turn the truck back on and initiate the same steps again. If the truck fails to shift into overdrive, there may be an issue with the sensor connecting the overdrive to the steering wheel panel.

Why is the transmission not shifting on my Chevy Silverado?

Take a couple of easy steps to see why your truck is not shifting. No need to panic yet. This article applies to the Chevrolet Silverado GMT800 (1999-2006). Your transmission is just supposed to shift and leave you alone.

Can a Chevy Silverado go from 1st to 4th shift?

Transmission is in Limp Home Mode or has no electrical power. Also, PCM has lots of error codes. No 1st or 4th, shift 2nd to 3rd by itself when put in D or OD and locks converter: Goes into gear but sluggish like brakes are on, can manually shift to 2nd to get moving, then put in OD and truck shift 3rd as well as 4th are OK.

Why does my transmission not shift into 3rd or 4th?

P0121 is a throttle position sensor and the P0171 ha to do with the engine running too lean Any luck getting this addressed since your last post, Ozzie? Not yet, I think I will try replacing the solenoids in the transmission first. If that doesn’t work then I guess its time to have it rebuilt.

Why is my 4L60E not shifting into overdrive?

As the 4L60E ages, one of the most common problems that it develops is that it won’t shift into overdrive anymore. Without overdrive, your vehicle turns into a time machine and takes you back to an era where it was the norm for a vehicle to scream down the highway at 3000 RPM.

How does engine braking affect the automatic transmission?

The impact of engine braking on the automatic transmission while going downhill is a debatable topic among many people. But, what exactly is engine brake and does it actually dwindles the automatic transmission efficiency?

How do you shift a GMC Sierra 1500?

You would have to push the 2HI and 4LOW buttons at the same time, and hold them there til the red NEUTRAL light came on, if it’s electronic shift. 19 people found this helpful. You might try to shift the transfer case, after warming up the vehicle for a good amount of time.

What causes a GMC to not shift gears?

Vehicle won’t move in any gear. Low transmission fluid level – One of the most common issues that prevent a GMC vehicle from shifting when placed in the Drive (D) or Reverse (R) is a low transmission fluid level. Shifter link – The shifter link connects the shifter to the transmission valve body.

Are there any problems with the GMC automatic transmission?

Overheating is a concern on GMC trucks that are used for towing or hauling heavy loads frequently. GMC vehicles that use a 4-speed automatic 4L60E or 4L65E transmission can develop a problem with gear shifts. This issue will manifest itself as improper gear changes that take too long to happen.

Why is engine braking when going downhill bad for automatic?

Engine braking helps you to maintain the control over the vehicle by reflexively reducing the wear on the brakes. Whenever you are driving down the hill, nothing could be more useful than engine braking and will not even affect the transmission. Wondering why?

What happens if your torque converter is worn out?

A worn out torque converter will cause a headache. The transmission is one of the most crucial parts of the vehicle. You will come into issues at some point. Hard shifts could come up and that is not good. You may experience shudders. The gears may become stuck. There might be jerking.

How do I reset Transmission Control Module Chevy Silverado?

I have a 2001 Silverado. To reset my TCM I turn on the key to the on position press the gas pedal to the floor for 10 seconds and then turn the key off then release the gas pedal and wait about 5 minutes to restart the engine. I have a 1999 Chevy 1500 I rebuilt the transmission so when I put it in drive its like it take off in high gear.

Why do you need a remanufactured automatic transmission?

JASPER’s remanufactured automatic and standard transmissions are designed for your peace of mind. You don’t have to worry about your bill growing as more and more parts need to be machined or replaced.

What do you need to know about Jasper remanufactured transmissions?

But you can relax. JASPER’s remanufactured automatic and standard transmissions are designed for your peace of mind. You don’t have to worry about your bill growing as more and more parts need to be machined or replaced. You don’t have to comb the junkyards for a used transmission, or trust your fate to a 30 day warranty transmission.

Where can I buy a GM transmission replacement?

Replacing a failed transmission can be very costly, which is why it’s so important to find the best price you can for a replacement online. We’ve listed some of the most common GM transmission part numbers below, making it easy to look up our pricing and place your order.

What’s the warranty on a new GM transmission?

Now add an extra 2-year unlimited mileage warranty on all powertrain parts! (Extend your warranty from 3-year 100,000 mile warranty to 5-year unlimited mile warranty). Just check the appropriate box at check-out!

What to do when automatic transmission won’t shift into 3rd gear?

Check the Throttle Cables. Changing the fluid solves plenty of transmission issues but if the problem of automatic transmission won’t shift into 3rd gear persists, the parts you should check are the throttle cables. A defective cable with excessive slack is likely to create issues with smooth shifting of the gears.

Why does my GMC Sierra 1500 not shift gears?

GMC Sierra 1500 Questions – Speedometer doesn’t work and transmission doesn’t shift gears. – CarGurus Speedometer doesn’t work and transmission doesn’t shift gears. The speedometer stays at 0 all the time. When the transmission is in drive it won’t come out of 1st gear.

What causes a GMC transmission to go bad?

Low transmission fluid level or dirty filter, which can cause overheating. High fluid temperatures will cause other issues with transmission operation. Most GMC transmission problems such as harsh shifting, delayed shifting, no gear, stuck in gear, no reverse or drive are quite often caused by low transmission fluid level.

What does it mean when your transmission is clunking?

Clunking or rattling in any system in your car usually means something either has or will soon fail catastrophically. If you’ve got these kinds of sounds coming from your transmission, have it checked out by a mechanic as soon as possible.

What does it mean when your transmission is whining?

Whining indicates a problem with the transmission fluid pump and could be due to a low level or a failing pump. Humming is usually an indication that there is bearing going bad in your transmission, but can also be confused with carrier bearings and wheel bearings so make sure to check all those bearings before jumping to conclusions.

Why is my car not shifting into second gear?

Check your transmission fluid levels first. Many times low fluid levels can adversely affect automatic transmission function and result in all kinds of performance issues, including the inability to shift into second gear. If your levels are good, move to the next step.

Why is my Shift Solenoid not working properly?

Diagnosis is key when it comes to transmission problems, as various issues can cause similar problems. Trouble with wiring or sensors could be at fault instead. A faulty shift solenoid should be replaced. In some cases, the solenoid is integrated into the valve body and isn’t serviceable.

Why does my transmission whine when I shift gears?

If the whining noise seems to change with gear shifts or is coming from your transmission it could be an indication that it is time for new transmission fluid.

Why does my Chevy Silverado shift so hard?

Recently it’s started to shift extremely hard under certain circumstances. It never does it when it’s cold (the trans, not ambient), and it sometimes does it when it’s warm. Anyone have an idea of what the problem might be? Have scanned for trouble codes? Most transmission codes won’t turn on the CEL. Take it to Autozone or O’Reillys.

Why does my Sierra 2500 shift so hard?

I have a 2000 Sierra 2500. Recently it’s started to shift extremely hard under certain circumstances. It never does it when it’s cold (the trans, not ambient), and it sometimes does it when it’s warm. Anyone have an idea of what the problem might be? Do you ever change the tranny fluid and filter?

Is there a GM hard shift transmission defect?

Ultimately, GM owners and lessees face mounting repair costs because of the alleged defect, the complaint says.

Why is my GM transmission not working properly?

Further, “The shuddering, shaking, jerking and hesitation is related to internal issues within the transmission and/or torque converter causing friction surfaces, hydraulic systems, and gears to not function properly, and resulting in metal shavings being circulated throughout the transmission,” continues the complaint.

What happens when you change gears in a GM car?

“Drivers attempting to accelerate or decelerate their cars feel a hesitation, followed by a significant shake, shudder, jerk, clunk, or ‘hard shift’ when the vehicle’s automatic transmission changes gears,” alleges the GM class action lawsuit.

Why is my GMC transmission not shifting properly?