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DISCLAIMER: AS AN AMAZON ASSOCIATE I EARN FROM QUALIFYING PURCHASES. THIS POST CONTAINS AFFILIATE LINKS THAT WILL REWARD ME MONETARILY OR OTHERWISE WHEN YOU USE THEM TO MAKE QUALIFYING PURCHASES. FOR MORE INFORMATION, PLEASE READ MY EARNINGS DISCLAIMER.

Transmission control solenoids are commonly located in an assembly called “Valve Body”, “Solenoid Pack”, or “Mechatronics” (a combination of the words mechanical and electronics). In most cases, you will need to remove the whole valve body to be able to have access to the solenoids. 

These solenoids manage the flow and pressure of the transmission fluid. The fluid runs through different circuits in the transmission unit and engages or disengages the gears, rear brakes, and clutch (or clutches).

All these actions require a good deal of pressure to generate them. Automatic Transmission manufacturers usually employ a color-coding system to make transmission solenoids easily identifiable.

Because of the complexity of the modern automatic transmissions, they don’t have just a control solenoid, but they have multiple solenoids that control different things.

To be able to replace a defective solenoid you will need to identify which one is faulty. I am not covering how to diagnose and replace a defective solenoid in this article, but I will give you a good introduction about how to locate them and all the work that you need to reach them.

This way you can evaluate if it is something that you would like to try to do on your own or if you’d rather take your car to a specialized shop.

Where Transmission Control Solenoids are Located?

Now you know that what you are looking for is something that is larger than a single solenoid – it’s a whole pack of valves and solenoids, and its location varies depending on the transmission brand, model, and manufacturer.

The most common places to find them are:

Location #1: Inside ATF pan

Very often you can find them inside the automatic transmission fluid pan. The ATF pan could be located on the lower part of the transmission, in the front, or at the sides of the gearbox.

The gearboxes that have their pans located underneath are easier to access because you can remove the ATF pan without having to pull the gearbox from the car.

Valve Body Located inside an ATF oil pan

Location #2: In front of the gearbox

This is common in gearboxes with “dry clutches” (for example a Volkswagen 0AM gearbox). In these cases, the mechatronics is located in front of the gearbox.

Since they are constructed as a sealed oil pan, you can remove them by disengaging them from the clutches forks. You will get the whole unit out with hydraulic oil inside the unit.

0AM Gearbox Body Valve

The following video will show you how to get access to transmission control solenoid in Dodge Neon:

Problems with an automatic gearbox

If you are looking for where to find a transmission control solenoid, you are probably experiencing problems with your automatic gearbox. As a useful piece of advice, I would like to say that not all of the problems that modern gearboxes have are related to broken transmission control solenoids or valves.

In some situations, the transmission control solenoids get stuck and you can try to fix the problem by doing a transmission fluid replacement (with the help of some additive in order to flush all the debris that could be sticking the solenoid).

I would also have the TCM scanned with proper software and conduct an output test to check the transmission actuator status. This will give you a hint about what’s happening inside your gearbox.

After doing all this, I would check for any electrical problems outside the gearbox. For example, check if the connections between the TCM and the mechatronics are good, or if you can see any hint of bad wiring.

Replacing a bad transmission control solenoid requires a lot of time, special tools, expertise and it’s not safe to do if you don’t have advanced mechanical skills. There are a lot of tutorials on the internet, but make sure that you are making it mostly for the satisfaction of being able to do it by yourself.

If you are just trying to save money, you will be risking harming your gearbox very badly and the cost of repairing it can be more expensive than buying a new transmission! It is very easy to miss the steps required or don’t do the job perfectly due to the lack of experience, and ruin everything.

Automatic Transmissions

The automatic transmissions of modern cars are faster, much more efficient, and “intelligent” than the older ATs that you could find in cars from the ’60s and ’70s. They have their own electronics, independent from the car ECUs (Engine Control Units).

They can even “learn” the driving patterns of the drivers in order to save fuel or to know if they need to throw shifts faster, in the case of drivers with a “heavy left foot (who enjoy using their cars in a sporty way). Modern auto transmissions can have from 4 to even 9 gears plus the reverse, and they can be faster in action than manual transmissions.

In order to accomplish these features, and always thinking about fuel efficiency as the main goal, engineers are tending to design automatic gearboxes with double-clutch systems, which require even more sensors, actuators, and advanced software. The “brain” of automatic transmissions is frequently called TCU (Transmission Control Unit), and it can be located in a module or inside of the “mechatronics”.

This article is for informational purposes ONLY and is NOT a replacement for professional advice!


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1 Comment

  1. Jonathan Stokes

    Catherine, you wrote an interesting post! Transmission shift solenoids are found within the valve body of an automatic transmission. These are embedded inside the valve body. Specific automobile models allow you to see valves without separating the valve body, but others need you to detach the valve body to see them.

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