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transmission défectueuse

Symptoms of a defective transmission

Like many people, you probably have a vehicle. Whether it’s a practical, economical car, a classic, collectable car, a light pickup, an SUV or a 4×4, you must take good care of it to prevent any potential problems and ensure the safety of everyone on the road.

Part of caring for your vehicle is having it inspected regularly, according to its age and mileage. You’ve undoubtedly heard mention of your automobile’s transmission, but you may be wondering what this component is, what exactly it does and what symptoms indicate that it may be defective.

We’re going to answer all of these questions—especially those regarding the symptoms of a defective transmission—to help you avoid possible headaches down the road.

Your vehicle’s drivetrain in detail

système de transmission d'une autoYour drivetrain is a complex system that’s essential in order for your vehicle to function correctly. The system encompasses a number of different components, including the engine, the transmission, the gearbox, the clutch, the drive shafts, the differential and the transmission fluid.

The transmission sends power and torque from the engine to the drive wheels using different gears. In this way, it helps adjust the power of the engine, depending on the vehicle’s speed, accelerations and decelerations. The gearbox adjusts the engine’s torque according to the vehicle’s needs and ensures that the engine maintains optimal RPM. Meanwhile, the clutch links the engine and the gearbox.

There are two basic types of transmissions:

  • A manual transmission (or “stick shift”) relies on the driver pressing on the clutch to disengage the engine and then manually changing gears using the shifter.
  • An automatic transmission manages the functions of the clutch and gearbox automatically.

Types of drivetrains

There are three different kinds of drivetrains:

  • Front-wheel drive: this is the type of drivetrain currently found in most vehicles. In this system, the drive shaft sends all of the power to the two front wheels.
  • Rear-wheel drive: in this case, the drive shaft sends all of the power to the rear wheels to propel the vehicle.
  • Four-wheel drive (or all-wheel drive): in this type of drivetrain, the drive shaft sends power to all four wheels. You’ll find this type of system on 4×4 vehicles and pickups, as well as certain SUVs, sports cars and sedans. This is the ideal system for driving in all types of weather conditions (rain, snow, ice, etc.), as it offers the best traction, handling and stability.

All-wheel drive systems fall into three different categories:

  • Selectable AWD: the vehicle normally operates in front-wheel or rear-wheel drive, but when necessary, the driver can manually activate the four-wheel drive system.
  • Part-time AWD: this system functions according to the same principle as selectable AWD, except that the vehicle activates four-wheel drive automatically when it senses the need.
  • Full-time AWD: in this case, the vehicle operates in four-wheel drive at all times.

Symptoms of a defective transmission

There are numerous signs indicating that your vehicle’s transmission may be defective, in which case you’ll need to have it inspected by a professional mechanic. The most common symptoms include the following:

Lack of responsiveness

Both manual and automatic transmissions are designed to work smoothly and effortlessly. If the transmission has difficulty engaging, is slow to engage or is unresponsive, this is usually a sign that something isn’t right. If you have a manual transmission, you may notice that the vehicle moves more slowly than it should in relation to the engine’s RPM. With an automatic transmission, on the other hand, the engine should go from Park to Drive without hesitation. If it doesn’t, there’s definitely a problem.

Inability to change gears

With a manual transmission, when the time comes to change gears, you should have no difficulty stepping on the clutch and moving the shifter. However, if you experience some sort of resistance or difficulty when doing so, this is most likely because of a problem with the gears or the transmission fluid.

Burning odor

If it smells as if something’s burning when you’re behind the wheel of your vehicle, this is never a good sign. The transmission may be overheated.

Transmission noise in neutral

Do you hear loud noises only when your vehicle is in neutral? This could be a sign that your transmission is suffering from serious mechanical wear.

Irregular gear changes and slipping

Both automatic and manual transmissions can exhibit problems with slipping gears. The vehicle may shift without resistance but fail to pick up speed or it may change gears constantly for no reason. The engine might even disengage, causing the vehicle to go into neutral by itself.

Strange sounds

If you hear persistent weird noises, such as humming, grinding or whining, that seem to be coming from your vehicle’s engine, they may actually be coming from a defective transmission.

Transmission fluid leaks

This bright red liquid enables your vehicle to shift, as it lubricates the gears and other mechanical parts. Check the level of your transmission fluid regularly to make sure that there are no leaks and check the color to make sure that it hasn’t darkened.


If your vehicle shakes or trembles when changing gears, instead of shifting smoothly, this is a sign that there may be a problem with your transmission.

Check Engine light

If your Check Engine light comes on, this may be an indication of a transmission problem, especially if there are other symptoms. In this case, it’s best to have your vehicle’s transmission checked by a professional.

Have you noticed any of these symptoms of a defective transmission in your vehicle?

Make an appointment with the experts at Trans-Mico, an automobile repair shop specializing in transmissions. Our certified mechanics will take the necessary time to conduct a full inspection of your vehicle and analyze the general condition of your transmission.

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