Why Is My Automatic Transmission Not Shifting Into High Gear?

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automatic transmission not shifting into high gear

Have you recently noticed that your automatic transmission is not shifting into high gears or won’t change gears at all?

One of the main reasons that an automatic transmission does not change shift into high gear is often a lack of fluid in the system. Generally, this is usually due to a worn-out oil seal which causes a fluid leak.

In this article, we will discuss this common issue and what to look for if you notice your transmission is not shifting into high gear.

Symptoms & signs your automatic transmission is not shifting into high gear

  • If you find that your vehicle automatically shifts from one gear to the next smoothly, but your transmission won’t shift into third gear or stays in first and second gears, then this might be a sign of a transmission problem.
  • On some occasions, your car’s automatic transmission may not even shift at all into the third gear. It will smoothly slide between every other gear like the first and second gear. Yet when you try shifting into the third gear, it just stays put in the second gear no matter how hard you push it. In such a situation like this, metal shavings may be present in the oil pain caused by the catalytic converter touching the side of the valve body.
  • If your car only works in reverse gear, it usually means you need to replace the friction clutches, piston collar, clutch rings or the hydroblock valve could be jammed.
  • Transmission is slipping when the vehicle begins to move, this is likely due to worn-out clutches.
  • When driving, the shifter is in the “D” position, but the car refuses to move when the accelerator pedal is pressed. In this case, the driver switches the automatic transmission to manual mode (if available), and the gears work well.
  • If you set the gear to drive “D” but the car refuses to move when you press on the gas, switch the clutch to manual mode (if your car has it) and the gears should work well.

When your transmission fails, your car’s electronic control unit (ECU) will put the transmission into safety mode. If you’re experiencing any of these transmission problems it’s recommended you take your vehicle to a mechanic so they can run an OBD scan to determine the exact issue.

Automatic transmission not shifting into 3rd gear – What should you do?

If you notice that your automatic transmission is not shifting, or won’t go into third gear like it should when needed. You don’t have to panic just yet because in most cases this issue can be resolved with a little bit of tinkering and some basic knowledge about cars.

In the majority of situations, an automatic transmission problem will be caused by a problem with the transmission fluid. This can be due to either a leak in your transmission or an issue with your transmission oil seal that has worn out and is now leaking.

Check transmission fluid level

Before you start tinkering with your automatic transmission, make sure to check the fluid levels. If you notice the fluid level is low, check for leaks in the fluid lines, pan gasket, cooler, and the input/output shaft seal. If there isn’t a leak, flush out the old oil and refill it with new transmission fluid oil. On top of that, you should inspect your radiator to see there are coolant fluid leaks.

Examine Powertrain Control Module (PCM)

If you’ve already checked the automatic transmission fluid level and there is no sign of a leak, then your next step should be to examine the Power Control Module (PCM). First read through any error codes that may be present on your dashboard. If you find an issue with one or more sensors in it, replace them before proceeding further.

A faulty PCM will affect the performance of transmission because it controls the gearbox mechanism in most car models. The PCM won’t have input if the speed sensor fails. In this case, the transmission won’t shift properly. To solve this problem, you should check the speedometer to see that it’s working correctly.

Shift lock release

Automatic transmissions in modern cars are designed to keep you from shifting gears unintentionally. These days, many automatic transmissions have a shift lock feature that is engaged with the engine running and your foot on the brake pedal to help prevent you from shifting out of drive while your vehicle is moving. If your engine is running, your foot is on the brake and your transmission STILL won’t shift, you could try the shift lock release. You can find the location of your shift lock release in your owner’s manual. It’s typically a small slot that can fit a key that is found near your clutch or steering column.

Check the throttle cables

If you still can’t figure out why your automatic transmission is not shifting into high gear, check the throttle cables. These are two thin metal wires that are attached to a rod with ball joints at either end and they control gas pedal position. If these wires become disconnected or lose their tension, it will affect automatic transmissions performance because they connect the throttle pedal to the engine throttle plate. You should be aware that there will be issues and also no smooth shifting of gears when you have a defective throttle cable that has excessive slack. This defective cable issue might even totally hinder the shifting of the gear. 

What about a manual transmission?

manual transmission

If your vehicle’s transmission is manual, here are the most common reasons why your transmission won’t shift properly.

Worn clutch

Even if your manual transmission is in gear, if the transmission slips, it could be stuck and not moving anywhere. This result is typically caused by a worn clutch. When a worn clutch on your vehicle goes unnoticed, there will be decreased friction for the engine’s power to transfer causing you to lose acceleration even when pushed into high gear.

Leaking clutch master cylinder

A leaking clutch master cylinder can cause the fluid to leak out, preventing sufficient pressure from being held in the system. This can lead to a clutch pedal that feels soft or sinks towards the floor, and may also make it impossible to get the car into gear.

FAQs

What are the symptoms of a clogged transmission filter?

When your transmission fluid is dirty or blocked by a clogged transmission filter, automatic transmission problems are likely to happen. The internal components won’t have the lubrication they need to function. You may notice that your transmission is not shifting properly, your transmission is slipping, your engine will start running rough or you won’t have any power when accelerating. If this happens, stop driving right away and turn off the car before anything serious can happen.

What are the signs of a blown transmission?

Understanding the basics of how a car’s transmission system works-what it does, and what breaks when it fails will help you diagnose realize when there is an issue with your transmission. To put it simply, the transmission controls speeds, shifts gears, and transfers power to the wheels. Signs of a blow transmission include:

  • Check engine light turns on
  • Hearing strange noises
  • Leaking transmission fluid
  • Transmission overheating
  • Slipping gears

What are the signs of a bad shift solenoid?

Transmission solenoids are one of your transmission’s many critical components. Solenoids control the flow of fluid throughout and open or close as per electrical signals they receive from an engine, which pulls its data from a series of speed sensors in that engine.

Transmission solenoids eventually wear out like pretty much everything in your car, but regular transmission service can help stave off their degradation.

Here are some common signs of a bad shift solenoid:

  • Delayed shifting between gears
  • You can’t shift gears, and your engine continues to rev even when applying the brakes.
  • You cannot shift out of neutral
  • Shifting gears become hard and slow

What’s wrong when your car won’t change gears?

Symptoms of a transmission issue can range from shifts that are delayed, jerky, or not smooth to clunking noises coming from the underside of your car. If you’re experiencing any of these symptoms, auto transmission oil, and filter replacement are highly recommended. You may also need engine mechanical repair work if other internal components have been damaged by the dirty fluid.

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