• Home  / 
  • Tips
  •  /  What is a Transmission Solenoid? Its Uses and Usual Problems

What is a Transmission Solenoid? Its Uses and Usual Problems

Transmission Solenoid?

A transmission solenoid is an essential part of an automatic transmission system of your car. The current breed of automatic transmissions utilizes pressurized hydraulic fluid in shifting gears. When you do need to change gear, your car’s computer system activates a transmission solenoid which then controls the transmission fluid into the valve body to direct the right gear that you desire.

Compared to a manual transmission which makes use of the clutch system in changing gears, cars with automatic transmissions rely heavily on a more complex hydraulic system.

What are the types of transmission solenoids?

There are various types of transmission solenoids that are directed to hydraulic valves and control the flow of transmission fluid that either closes or open up. Such transmission solenoids include the transmission shift solenoid, torque converter clutch solenoid, lockup solenoid, and the transmission control solenoid. There are speed sensors around the engine that in turn activate the solenoids.

While these types of transmission solenoids have different uses, the operating principle is the same throughout. Since a transmission solenoid is an electromechanical device, it sources its electrical signal primarily from the car’s battery. These solenoids are commonly installed all at the same time or in a combination of types, depending on car model.

You can check out the types of solenoids that are installed in your car by getting the information from the owner’s manual. If you do not have your car manual in your possession, you can ask your mechanic when you have your regular maintenance done.

What does a transmission solenoid do?

Cars with automatic transmission are dependent upon bands and clutch to shift gears. The only possible technique that this could be executed is by fluid pressure. While the transmission solenoid is the one which closes and open up the hydraulic valves in the valve body allowing the entry of transmission fluid in controlled quantity.

The solenoid is comprised of spring loaded plunger enfolded with a coil of wire that is communicating with the engine’s sensors. When this coil of wire receives an electrical signal from the Transmission Control Module (TCM) or the Engine Control Unit (ECU) of your computer, this opens or closes the transmission solenoid.

While the sensors determine when to shift gears depending on the vehicle’s speed, the transmission solenoid is powered up that enables it to open the plunger allowing transmission fluid to pass. Other transmission solenoids that are not energized will remain close to its normal position.

What are the signs of solenoid problem?

Since transmission solenoids are the ones responsible for controlling fluid pressure, you can easily determine that this will be the culprit when shifting problems arise. However, there is deeper meaning when other troubles regarding transmission are observed. If there is not enough fluid pressure flow in the transmission, the clutch plates may overheat, while over pressure will cause rough shifting.

When the “check engine” light does not blink but you are having shifting gear problem, the most likely cause is a mechanical issue. When this happens, the best solution is to replace your transmission solenoid.

However, if your “check engine” light flashes on and your solenoids act irregularly, there might be a problem on the solenoids’ electrical system. This could be corrected by having a quick scan on your computer. These are the common signs of a malfunctioning solenoid:

  • Slow or inconsistent shifting

If you are experiencing a delay in shifting, which takes about a few seconds or longer, there could be a problem on one of the transmission solenoids. When this happens, the car run as if it is in neutral and can’t be able to accelerate.

  • The transmission is unable to downshift

When you are having a malfunctioning shift solenoid, you won’t be able to downshift or having difficulty in downshifting.

  • The transmission fails to shift to the correct gear

If you are unable to shift to your desire gear and what happens is you are always in the wrong gear, skipping a gear, and is shifting unpredictably back and forth, you have probably a defective transmission solenoid.

Here are some excellent brands of transmission solenoids

For a good replacement for your ailing transmission solenoid, try this best-selling brand: Wisamic Automatic Transmission Shift Control Lock Up Solenoid. This product from Wisamic is an assembly for 1994-2000 Honda Civic models, with replacement part no. 28300-P24-J01. Check this one out on Amazon so you will have a great deal.

Another ideal replacement part is the Delphi SL10007 Automatic Transmission Solenoid. This product from Delphi fits most of the current models of cars, check this one out if it is suitable for your car. Also available from Amazon.


A transmission solenoid is surely a required element of a working transmission system in your car. Any unusual behavior of this element is sure to give you some signs and symptoms. It is better that you have knowledge about the functions and possible malfunctioning of this device so you could know when you have to visit your expert mechanic for the thorough check up of your car.

Please send us your comment and question about this article.

About the author

Carolina - Care My Cars

Car, from a long time ago is the main transport vehicle for people which help to move faster and protect users from the unstable of weather such as sunlight, heat, or rainy. So that, the demand of car and the search for the best and a suitable car in the market are higher than ever and you also are one of the people who is looking for the answers from the market. Welcome to caremycars.com and I hope that my articles can help you to solve the problems that you are in with the most effective way. If you think my website give values, you can donate me by the ways. Donate: - Bitcoin (BTC): 1Eoz8vhfAjD4cCrq2jec3V38mmaHehedXU - Etherium (ETH): 0xd10809ae634117bf6c52Af884a8bc8B84D436e3b - BicoinCash (BCH): qqp4yjqx2g57exes0stsnkgk5e9uyu5clvrjj4ew44 Thank for all

Leave a comment:

Help me to prevent from spam! Thanks you *