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My Transmission Won’t Shift When Accelerating: Tips, Facts & FAQs

Manual Transmission

The transmission is one of those parts in a car that you don’t really pay much attention to. It’s just there, and it works. However, when it starts to malfunction, trouble follows. For example, what do you do when it refuses to shift gears when gaining speed? Well, the first thing to do would be to check the ECM. Second, inspect the clutch disc and the transmission fluid. Fixing weak connections could also solve the issue.

Yes, this will take some trial and error before you get to the bottom of it. In this guide, we’ll cover the most common causes of the shifting problem and share tried-and-true techniques for fixing them. Next, we’ll talk about how to increase the transmission’s lifespan and more. Let’s get to it!

car and road divider

How Does the Transmission Work?

Image Credit: Dibjo, Pixabay

These days, most vehicles can be equipped with either a manual or automatic transmission. As the name suggests, an automatic gearbox does all the shifting autonomously, while a manual transmission relies on the driver for that. Manual transmissions are cheaper but a bit harder to master, especially for a first-time driver. They consist of a shifter, the actual gears, the input/output shafts, and a clutch pedal.

The driver selects a gear and activates the clutch. You’ve got dual-clutch (partially automated), AMT (mostly the same, but cheaper), unsynchronized (only used in older cars), and synchronized (easier to use) manual transmissions. Automatic transmissions, in turn, don’t have any clutches—they’re replaced by torque converters. And there’s no gear shifting as the computer handles everything.

Fixing the Shifting Problem: A Detailed Guide

Detailed Guide
  • The first thing to check would be the ECM. It stands for Electronic Control Module, and when it’s malfunctioning, you’ll have a hard time shifting through the gears. It’s the onboard computer that controls the air-to-fuel ratio, emissions, and gear shifts. If you’re lucky, the problems with shifting will be caused by bad connections, which are easy to fix. But if it’s the software, only a professional can repair it.
  • Worn-out sensors and bad solenoids (alternatively known as valves) can also make the transmission “act up” when going up or down the gears. The mechanics are calling this a “no shift” condition. It prevents the driver from successfully switching between gears. Again, have a mechanic check the solenoids and sensors. Most likely, they’ll find that a broken shifter cable is causing all this trouble.
  • Next, we would recommend checking the engine. It might be that blown fuses or bad connections (like throttle cables) inside of the motor are to blame here. If you have experience with engines, replacing these won’t be a problem. If not, an auto shop will take 1–2 hours to handle everything.
  • Couldn’t find any issues with the motor? Then check the transmission fluid. Is there enough of it, or maybe the fluid levels are low? If so, you need to top it up. But before you do that, it would be best to flush the old fluid, as it will, most likely, be contaminated. This will take some time—keep that in mind. If you don’t see any metal pieces mixed in with the fluid, that’s a good sign; it means the fluid is relatively clean.
  • Owners of manual transmissions should also examine the clutch disc: it tends to wear out over time. A new one will set you back $1.1–$1.3K, with mechanics charging $600–650 for the labor. While you’re at it, have the synchronizers diagnosed as well. When they wear out, the transmission constantly fails at going up or down a gear when accelerating. New “synchros” cost roughly the same to replace.
  • Solenoids are another common cause of failed shifting upon accelerating. Start by removing the plates with a screwdriver; next, examine each solenoid. Look at the rubber seals first. They need to be squeaky-clean. If there are any signs of leaks, you have to replace that solenoid. A pack of these costs $50–$300.
  • When was the last time you checked the torque converter? It might very well be that the gearbox isn’t shifting properly because this part is malfunctioning. Without it, the wheels won’t turn, essentially making the car useless. A faulty converter leads not only to trouble shifting but also to smoke and even burning.
  • Lastly, we’ve got the gear shift lock. This is a system that protects the car from accidental gear shifts (like maybe a reckless passenger or a child playing around with the gearbox). With the lock activated, the transmission won’t shift when accelerating. Luckily, this one’s very easy to override; on the console, you’ll find a slot. Insert your key, and that should unlock the gearbox!

Should You Hire a Mechanic for This?

Automatic Transmission
Image Credit: AutoPhotography, Pixabay

If you can afford to pay an auto shop to fix the transmission, then yes, you should definitely do that. First, they’ll have the necessary equipment and expertise to properly diagnose not only the gearbox but the entire car. They’ll read the error codes using a scanner (the “Check Engine” light might indicate that there’s an issue with the transmission, not the motor) and come up with a solution.

For an extra fee, the specialist will also inspect the transmission for any signs of leaks, cracks, dents, and wear. Worn-out seals/bearings won’t cost much to replace. The same is true for patching a leak. However, if you’ve been driving on low fluid/oil levels for a long time, exposing the transmission to extreme heat, that will cost a lot more to fix/replace.

How Long Do Transmissions Last?

In cars, the gearbox is responsible for preventing excessive engine wear and tear. Besides, without a transmission, the engine will take forever to accelerate, and it will get loud as you approach peak RPMs. It’s also the transmission’s job to “feed” the power/energy generated by the engine to the wheels. You can find it installed on the chassis of the car in the front.

It does wear out over time, though, especially if you do lots of off-roading or take part in competitive racing. On average, the transmission in a modern-day car can serve for 100K miles. Given that the average American drives 10–15K miles a year, it will last for at least 6–7 years. However, if you take proper care of it, the transmission will go on for 250–300K miles!

Manual Transmission
Image Credit: real-napster, Pixabay

car and road divider

Tips for Increasing the Lifespan

While the transmission is rather tough and can handle natural elements, rough driving conditions, and lots of “abuse”, it still needs care. Here are the best practices for extending its life cycle:

  • Don’t skip regular maintenance. Most drivers know how important it is to change engine oil, replace spark plugs, and fix tire alignment. Sadly, the transmission doesn’t always get the same kind of attention. So, if you want it to last a bit longer, make sure to have the filters and fluid changed regularly. It’s recommended to do this once in 12–18 months or 20–30K miles. An oil flush every 40–50K miles would also be great.
  • Check on the fluid. Transmission oil has two important tasks. First, it takes the heat away from the various mechanical components. Second, it minimizes wear/tear due to excessive friction. When there isn’t enough transmission fluid, that can lead to overheating (and expensive repairs). Check it once every 1–2 months. Also, consider using synthetic oil, as it does a better job of protecting the gearbox.
  • Think about buying a cooler. The rule of thumb here is—the lower the temperature in the transmission, the better. That’s why a cooler will come in handy. It can dramatically increase the service life of the transmission and won’t cost you a pretty penny (you can get it for $70–$80). Aim for <200 degrees. If the temps go above this mark by 20ºF, that will reduce the lifespan by 40%–50%!
  • Be a conscious driver. Accelerate slowly and try not to do any aggressive driving. Next, give both the transmission and the engine some time to warm up. Remember: the colder it is outside, the thicker the fluid will be. Keep your eye on the RPMs and only hit the gas pedal when they go down. Finally, resist the urge to shift between gears while the car is still moving and keep your foot off the brake pedal.

car and road divider


The transmission is quite a sophisticated mechanism. Without it, your vehicle won’t be able to start or work properly. And when it fails at shifting through gears when accelerating, that can lead to all kinds of unwanted consequences, including slow, inconsistent performance, faulty starts, and more. In the worst-case scenario, you’ll end up in an accident. Fortunately, this issue can be solved.

It will take some time, expertise, and the right equipment, though. That’s exactly why letting a licensed mechanic handle everything is recommended. But, if you know your way around cars, fixing the transmission manually will save you a lot of money. Make regular maintenance or trips to the closest auto shop a part of your routine, and happy shifting!

Featured Image Credit: Globetrotter78, Pixabay


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