Sensors play a vital role in vehicles. Sensors monitor fuel consumption, emissions and even vehicle engines. Sensors also aid both the driver and passengers of the car as well. With sensors, car makers can create and launch vehicles that are more fuel efficient, comfortable and safer to drive. Car sensors are intelligent and important computer systems that control various aspects of your vehicle. Some of those include coolant levels, oil pressure, temperature, emission levels and more.
Electronic Control Unit
All of the sensors inside of a vehicle are connected to the Electronic Control Unit or the ECU. The ECU contains the “brain” or the firmware (hardware as well as software). While the hardware houses the electronic components, those components are printed on a circuit board (PCB) with a microcontroller (MCU) chip. That MCU processes the inputs provided from various sensors in real time.
Even with their intelligence, faulty or bad sensors can cause transmission problems. We’ll look at this a bit more in-depth.
What Sensors Are on A Transmission?
Powertrain Control Module Microprocessor
The Powertrain control module microprocessor can be called the brain of a vehicle. It receives its information by other sensors located around the vehicle. These transmission sensors have the job of shift timing as well as additional aspects of vehicle shifting. The TCM or the transmission control module is an additional microprocessor that regulates the function of the transmission. The microprocessors are given information from the all the sensors. Here are some of the most common transmission sensors in a car. Here are just some sensors that can cause problems with a car’s transmission.
Vehicle Speed Sensor
The Vehicle Speed Sensor measures a vehicle’s speed. If it malfunctions or fails to work, then the automatic transmission may not operate as it should. This sensor may also cause the automatic transmission to go into failsafe mode – giving the appearance that the issue is more severe than it really is.
Turbine Speed Shaft Sensor
The Turbine Shaft Sensor has the job of measuring the input shaft speed of the automatic transmission. As the electronic transmission control module uses the information given by the TSS, it helps configure the exact amount of torque converter clutch slippage. If failure happens, then there is generally an automatic transmission fault code that is produced.
Transmission Input Speed Sensor
The input speed sensor has the task of measuring the RPM of the input shaft of the transmission. With a running engine and a vehicle in forward or reverse gear- and the vehicle not moving, the input shaft of the transmission will also not be moving. This is due to the torque converter- allowing this to happen. This is also commonly known as “slipping”.
Transmission Output Speed Sensor
The job of the output speed sensor of a vehicle, is to measure the rotational speed of the output shaft in RPMs.
Intake Air Temperature Sensor
The Intake Air Temperature sensor’s job is to measure the temperature of the air as it enters the engine’s intake assembly. This sensor also controls the air/fuel mixture within the engine, ensuring proper ratio for the most effective as well as efficient operation. The sensor is also a component of the pressure control system for the automatic transmission. If failure of this sensor takes place, then the transmission may produce both soft as well as hard shifting or soft shifting. Drivers may also see transmission fault code.
Transmission Fluid Temperature Sensor
The transmission fluid temperature sensor has the job of gauging the temperature of the transmission’s automatic transmission fluid. This sensor is oftentimes used to delay the engagement of the converter clutch as well as overdrive, when the vehicle’s engine has not warmed up enough. During failure of this sensor, you may or may not notice it immediately; but there will eventually be transmission fault code that will register.
The Manual Lever Position Switch
The Manual Lever Position Switch is also called the Transmission Range sensor. Its job is to tell the PCM the position of the transmission shifter. The PCM will then utilize this data to control which gears of the transmission to disable or enable. During failure of this sensor, your car can enter into the wrong gear starts. Additionally, they will be no upshifts either. You will feel something that resembles an “out of gear” or a “falling out of gear” sensation.
Throttle Position Sensor
The job of the Throttle Position sensor is to gauge throttle position- that is controlled by the gas pedal. This sensor is also used to gauge the engine load. If failure happens, there can automatic transmission shifting problems. This sensor is also utilized to measure as well as control engine performance by increasing the amount of fuel provided as the throttle opens.
Coolant Temperature Sensor
The job of the Coolant Temperature sensor is to measure the engine coolant temperature. Additionally, this sensor is also utilized to prevent overdrive and the converter clutch should the engine become too cold. The coolant temperature sensor is also utilized by the power train control module to change the engine’s air-fuel mixture ratio, providing a richer mixture, when the engine is cold. If failure occurs with this sensor, then it will produce an automatic transmission fault code.
Where Is the Transmission Sensor Located?
The transmission speed sensor can be found in the rear of a longitudinal mount transmission. For transaxles, you can find the speed sensor on the long side of the output shaft.
Can A Bad Torque Converter Damage Transmission?
The short answer is yes. Bad torque converters can cause friction damage, transmission fluid degradation and even overheating. The longer these problems exist, the more damage your car will endure.
What Are the Symptoms Of A Bad Automatic Transmission Position Sensor?
When the position sensor experiences failure, the car’s computer will not have any idea which gear the driver has selected. Due to such, the car’s engine will likely fail to start because the computer will probably not know that the transmission is in neutral or park. If the gear position sensor experiences failure that still allows the car to start, only one or two gears will likely be available for usage. You may also see warning lights appear on the dashboard, and the transmission may not drive in the range chosen by the driver. Although a dangerous situation, it’s quite unlikely.
Can You Drive with A Bad Transmission?
Driving a car with a bad transmission is never a good idea. Although technically, the car can still be driven, you are doing tremendous damage to your car. the vehicle can still be driven, but every time you do drive it you are risking your chances. If small metal shavings begin to slough off and mix with your coolant, you’re looking at a big repair on your hands.
How Much Does It Cost to Replace A Transmission Sensor?
The average cost for a transmission position sensor repair or replacement can run you about $240 all the way up to $350. While our estimates are general, you have to factor in labor as well. Those costs can run you anywhere between $125 and $160.
Can I Drive My Car with A Bad Automatic Transmission Position Sensor?
Most vehicles are quite useless without a transmission position sensor that is working properly. Even if the vehicle will drive in in “limp mode”, that drive home will be choppy, slow and will consume lots of your car’s fuel. So, try to get to a mechanic as soon as you notice the issue. If you decide to drive home, you can be left stranded.
Maybe I can change the sensor myself. So, how do you change a transmission sensor?
Park the vehicle and make sure that the engine is off. Try to let the vehicle completely cool for about an hour or so. When the car is cool, you can jack the front of the car up till you have enough room to slide underneath for the repair.
Crawl under the vehicle carefully and then locate the speed sensor. You can find it on the bottom of the transmission. And it is identifiable by a small plug that is sticking right out of the transmission with an electrical connector plugged into it. After you locate it, be sure to carefully squeeze the release tab on the electrical connector. You can also squeeze till you pull the connector out of the sensor.
Grab a wrench to clasp as well as gently twist the sensor counterclockwise until it’s loose enough to remove. Then, carefully remove the sensor from the transmission.
Align the replacement sensor in place as you carefully twist the sensor clockwise until the sensor is secured and can’t go any further. Slowly and carefully plug the electrical connector into the appropriate plug on the sensor. You have now replaced the sensor.
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