Why is Automatic Transmission Not Shifting Into High Gear?

An automatic transmission not shifting into high gear is a real concern, especially when you’re on the road. Automatic transmission systems are used in modern vehicles to make driving smooth and convenient.

But sometimes the automatic transmission does not shift into high gear. If we examine the reasons why an automatic transmission does not shift into high gear, there can be many different reasons for this problem.

What Does Automatic Transmission Not Shift Into High Gear Mean?

When the automatic transmission is not shifting into a higher gear, it means that the automatic transmission is failing to engage the highest gear available.

Automatic transmissions have many gears, from first gear to high gear. Shifting of these gears is done according to the RPM and engine requirements. The purpose of switching to a higher gear is to achieve better fuel efficiency and higher speed at lower engine RPM.

Why Is Automatic Transmission Not Shifting Into High Gear : Causes

If the automatic transmission is not shifting into higher gears, the main cause is a low transmission fluid level or leakage. Other causes could be a bad torque converter, a faulty PCM, a damaged shift interlock solenoid, or a faulty transmission sensor.

Let’s take a closer look at all the reasons an automatic transmission may not shift into high gear, so you can take steps to fix it.

1. Low Transmission Fluid Level

Most automatic transmission malfunction problems are caused by low fluid levels. Since fluid is a vital component in automatic transmission systems, it plays a vital role in the functioning of the torque converter. The torque converter transfers engine power to the automatic transmission with the help of transmission fluid, thereby setting the vehicle’s drive wheels in motion.

But in automatic transmission systems, when the fluid pressure is low, the torque converter’s propeller is unable to transfer fluid to the turbine at full power, causing the automatic transmission to be unable to shift to a higher gear. If the fluid level is too low, the automatic transmission system may even fail completely.

2. Faulty Power Control Module (PCM)

The PCM module plays a vital role in completely controlling and operating the vehicle’s automatic transmission system. The PCM module controls the automatic transmission function from signals from the automatic transmission sensor.

But sometimes, due to some reason, the PCM module installed in the vehicles gets damaged or some other type of error occurs, due to which the PCM module becomes unable to operate the automatic transmission.

Due to this, there is no problem with initial gear shifting in automatic transmission. But the automatic transmission is unable to shift into high gear.

3. Faulty Torque Converter

A torque converter is used in place of a manual clutch in automatic transmission systems. The torque converter transfers engine power to the automatic transmission through transmission fluid.

But sometimes the impeller in the torque converter fails to send fluid to the turbine during high acceleration, or the turbine is unable to rotate a sufficient amount of fluid during high acceleration.

Due to this, the initial gears (first, second, and third gears) of the automatic transmission shift easily during low acceleration of the engine. But at high engine acceleration and high vehicle speeds, the propeller and turbine of the torque converter may not engage properly, and the automatic transmission does not shift into higher gears.

4. Damaged Shift Interlock Solenoid

The gear shift interlock solenoid is included in the automatic transmission system. This shift interlock solenoid can cause gear shifting problems in an automatic transmission when it is damaged or malfunctioning.

In an automatic transmission, the shift interlock solenoid locks the gear in the selected position and the PCM module also automatically changes gears in the automatic transmission through the shift solenoid. The automatic transmission shift solenoid helps to shift gears.

But a bad or damaged automatic transmission shift interlock solenoid may also cause the automatic transmission not to shift into high gear.

5. Faulty Transmission Sensor

Automatic transmission systems have input and output sensors to monitor gear speed and position. These sensors send gear position and speed signals to the PCM unit in the automatic transmission, and based on these signals, the PCM unit automatically shifts gears according to the gear ratio and speed.

If any of the sensors in the automatic transmission are faulty, the PCM is unable to correctly determine the gears and speeds of the automatic transmission.

Therefore, the automatic transmission does not shift into high gear. However, if the sensor has gone bad, this problem can be seen in the shifting of the first, second, and third gears.

How To Fix Automatic Transmission Not Shifting Into High Gear?

To fix the problem of high gear shifting in an automatic transmission, the first thing to do is investigate the cause of the problem. The steps to fix it are as follows.

1. Check & Add Transmission Fluid

In an automatic transmission system, the most common reason for shifting to a higher gear is a low transmission fluid level. So first of all, check the fluid level in the automatic transmission. If the fluid level is low, add transmission fluid. so that the transmission fluid level can be completed.

2. Check & Replace Transmission Sensor

Input and output sensors are installed in the automatic transmission system. monitors the position and speed of gears in an automatic transmission system and sends its signal to PCM.

The PCM automatically changes gears via the shift solenoid based on data from the automatic transmission’s gear speed and position via the sensor. But all this functioning is disrupted due to a faulty transmission sensor. For this, you need to check the automatic transmission sensor. If the sensor is bad, replace it with a new one.

3. Check PCM & Replace Bad PCM

The power control model is an important part of the automatic transmission system. The PCM manages all the functions of the automatic transmission. But a bad PCM is unable to manage the full functioning of the automatic transmission system.

Therefore, the PCM should also be checked and if it is bad, it can be replaced with a new one. However, this can be a matter of high cost.

4. Check & Replace Torque Converter

The torque converter is an extremely useful part in an automatic transmission. The automatic transmission of any vehicle cannot operate without a torque converter. The torque converter transfers the engine’s rotational power to the automatic transmission.

Therefore, the torque converter should also be checked if there is a problem shifting to high gears in an automatic transmission and in the event of a torque converter failure, it should be replaced with a new one..

However, this is a high cost operation. Because the automatic transmission needs to be disassembled from the engine to replace the torque converter.

Why is My Automatic Car Not Shifting Gears?

When your automatic car fails to shift gears, there can be several reasons for this problem. Typically, a low transmission fluid level, a faulty transmission control module, a faulty shift interlock solenoid, or a bad torque converter can cause gear change failure.

Therefore, to get the exact solution to this problem, you should consult a professional mechanic who can thoroughly inspect your vehicle’s automatic transmission problem and suggest the appropriate repair or replacement to solve the problem. .

FAQ’s

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