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What is a Transmission Solenoid?

transmission solenoid

On average, your car is made up of about 30,000 parts - from the engine itself all the way down to the nuts, bolts, and bearings that keep everything together. And each of these parts works with the others to create the nice ride that you have.

One very necessary component is your transmission. Using a combination of sensors, gears, fluid, and hydraulics, your automobile is very easily able to drive at various speeds with smooth transitions. And much of this is thanks to the transmission solenoid within it. 

A solenoid is a small part with a big role. Let’s take a closer look at what this transmission solenoid is - and how to tell when it is not performing well. 

What is a Transmission Solenoid? 

Simply put, a transmission solenoid controls the flow of fluid throughout a vehicle's transmission system. Often having two or more, these small valves open and close to allow fluid to flow into and throughout the transmission when it is electrically signaled to do so. 

When running smoothly and allowing the flow of transmission fluids, solenoids will let the vehicle's speed accelerate and decelerate smoothly. However, when they aren’t as efficient in moving the fluid - or they stop altogether - problems can occur. 

Being aware of any signs of potential issues with your transmission solenoid should prompt you to seek repairs before things get worse. 

Signs of a Transmission Solenoid Problem

Transmission solenoids are designed to last - some even for the life of the vehicle, But, it is not at all uncommon for them to fail. This is especially true since there are multiple parts that make up the unit. 

Below are a few signs that your transmission solenoid may be struggling: 

  • Delayed Shifting. Your car should automatically switch from gear to gear smoothly as your speed increases and decreases. 
  • Skipping Gears. If there are issues with certain gears, they may be skipped over. This could be due to a bad solenoid. 
  • Unable to Move Out of Gear. If your car is stuck in the same gear and will not shift, this is a big indicator of a bad solenoid. 
  • Check Engine Light. If the check engine light is illuminated on your dash, it is always a good idea to get your car checked as it could be your solenoid. 
  • Sluggishness. If your automobile suddenly seems to lose its ability or gumption to move when you want it to, it could be protecting itself from gear trouble due to a bad solenoid. This is often referred to as limp mode. 

In general, having a bad solenoid will often impact how well (or poorly) a transmission shifts between gears. If you start to notice anything different as you hit the gas - you should have your car examined by a transmission specialist. 

Can You Drive with a Bad Transmission Solenoid?

Continuing to drive an automobile that is showing signs of an ailing transmission solenoid can be dangerous and can lead to bigger issues down the road. For instance, it could cause you to drive in gears that do not match your speed. Doing so can also lead to an overheating - or transmission failure.

In other words, this is never a good idea. 

Having Transmission Solenoid Trouble? 

If you are experiencing signs of trouble with your transmission solenoid, then it is time to contact Circle D Transmission at (713) 895-7019. Or, schedule an appointment online. 

We are here to diagnose an issue with your transmission, as well as offer preventative service to the residents in and around the Houston area.

What’s the Cost of Transmission Diagnostics in Houston, TX?

transmission part

You rely on your motor vehicle for many different things. So if it begins to show signs of transmission trouble, undergoing a diagnostic test using scanning software will allow the mechanic to pinpoint exactly what needs their attention. Of course, this may leave you wondering just how much transmission diagnostics in Houston, TX is going to cost you.

Here’s everything you need to know.

Signs of Transmission Trouble

The transmission is an integral part of your automobile. And knowing what signs to look for is important. If you notice any of the symptoms of transmission trouble, it is a good idea to get your car to the mechanic for transmission diagnostic testing as soon as possible.

  • Unusual noises, such as humming, clunking, or whining sounds

  • Burning smells

  • The check engine light is on

  • Hesitation when driving or no response when in gear

  • Transmission fluid leak

  • Shaking when shifting gears

  • Won’t go into gear (or slow to do so)

  • Slipping gears (changing gears without you doing it)

  • Noisy when in neutral

What is a Transmission Diagnostic?

Not too long ago, most mechanics had to take their time scouring over every detail of a transmission to determine what repair needed to be made. Fast forward to today and while many transmission experts will still do these manual assessments, diagnostic tools are now also used. Most diagnostic tools consist of factory (or even aftermarket) software that is plugged into the OBD2 port in order to take a look inside the car and give insight as to the problem.

It is common for some minor transmission issues to be diagnosed quickly. But sometimes it takes time to test different real-life conditions and determine what the actual problem is. A thorough mechanic will go through each of the individual components that create your transmission to determine which ones may need attention.

The evaluation should include:

  • A check of the transmission fluid

  • A scan using the diagnostic tool

  • A road test to duplicate your complaint

  • A lift inspection (if necessary) to pinpoint a leak or noise

It is important to note that older cars will require a more in-depth look that relies less on diagnostic tools and more on manual diagnostic skills.

What’s the Cost of Transmission Diagnostic?

The cost of transmission diagnostics in Houston, TX will depend on where you get the testing done as each repair shop will have its own prices. On average, though, you can expect to pay between $100 and $175.

Your car’s transmission is incredibly complex and it requires a lot of skill in order to repair it when it goes awry. That means you cannot just settle for any mechanic. You may be tempted to opt for the cheapest quote you get, but you could end up with a mechanic that causes more damage.

Diagnostics at Circle D Transmission

If your vehicle is showing signs that the transmission may be in trouble, don’t delay in seeking diagnostics testing. CDT offers transmission diagnostics at an affordable rate performed by mechanics with a high level of precision. If you’ve been looking, we are the right repair facility.

To learn more, contact us at 713-895-7019.

What to Do When Transmission Starts Making Noises

pieces of an automotive transmission

As the heartbeat of your car’s engine, the transmission is responsible for ensuring the proper amount of power is sent to your wheels to drive at a given speed. In other words, the transmission makes sure the engine spins at the right rate, to pull power from the engine to give to the wheels. So if your transmission begins to make noises, that’s an indication that something is wrong, and other problems may follow. If your transmission begins making noise, take it to a reputable transmission center ASAP. Small problems can often be fixed early on,  to prevent them from turning into costly repairs.

Signs of Transmission Problems

Strange sounds in your vehicle can be an indication of a transmission problem. If you hear buzzing, whining, humming, or clunking noises, it is essential that you take your car in for transmission diagnostics as soon as possible. These sounds can indicate transmission failure. However, keep in mind that transmissions are made up of hundreds of parts, so knocking or clicking noises may also just be a worn-out case, or bearing, requiring a minor transmission repair.

Other signs that you could have a problem with your transmission include:

  • Leaking fluid

  • Grinding, shaking, jerking

  • Delayed shifting into gear

  • Inability to shift gears

  • Burning smell

  • Service engine light

If you experience any of these problems, it’s smart to take it to a top-rated shop for transmission diagnostics as soon as you can.

Common Problems with Transmissions

A lot of things can go wrong with your car’s transmission but some transmission problems tend to occur most frequently. These include:

Dirty or Low Transmission Fluid

Whether you drive a manual or automatic, plenty of clean transmission fluid is essential to keep your car running properly. Low fluid due to a leak, or dirty fluid can lead to overheating, grinding, gear slippage (automatic vehicles), or lack of power (manual cars).

Worn Needle Bearings

In automatic vehicles, the needle bearings prevent gears in the torque converter from grinding. If they wear out, you’ll likely hear noise from your transmission that sounds like grinding or a brushing noise. If you take your car in for repair quickly, you can prevent premature failure of your gears.

Aged Gear Synchronizers

Manual transmission vehicles rely on the gear you are about to shift into, to spin at the same speed that the gear you’re shifting from. When the synchronizers (synchros) become worn down you’ll experience problems. Left untreated, these worn synchros can lead to complete transmission failure.

Worn Clutch

Worn clutches in manual transmission cars can be due to fluid leaks, or improper driving. Fortunately, most clutch replacements are quick, affordable fixes.

Poor Maintenance

Believe it or not, the number one cause for transmission problems is lack of owner maintenance.  All vehicles have manufacturer maintenance recommendations, but many car owners don’t follow them. Simple preventative transmission services can prevent the majority of transmission problems.

Transmission Diagnosis in Houston

To schedule preventative transmission service, or to diagnose a problem with your transmission, contact Circle D Transmission at 713-895-7019, or book an appointment online. 

Understanding the Cost Behind Transmission Repairs

mechanic working on vehicle

Dealing with a transmission repair likely wasn’t on your to-do list - or even in your budget. But it is definitely a necessity when it comes to having a working vehicle. Without a functioning transmission, your car isn’t going to run properly (or maybe even at all).

The costs of rebuilding or replacing your transmission can vary based on several factors, but it usually runs anywhere from $3,000.00 to $5,000.00 on average. And, while we know how important this part of the car is, what makes it so costly?

Factors That Impact the Cost of Transmission Repair

The transmission of your car is one of the main parts. It also has many different parts that make it a functioning system. So, when something goes wrong, it could be a number of different things - as well as vary based on certain factors.

  • The Symptoms. Like we said, there are many things that can go wrong. Are you smelling a burning smell? Is your check engine light on? Will the car not drive at all? Depending on what the exact issue is will impact the overall cost of the repair.
  • The Type of Transmission. Is your car manual or automatic? This matters as automatic transmissions are more complex and, as a result, their repairs tend to be more costly.
  • The Year of Your Vehicle. If your auto is newer, then the parts for the repair should be relatively easy to find. However, they are likely to be more expensive. For older cars, finding the parts may be difficult and also lead to expensive parts.
  • The Make of Your Vehicle. Automobiles made outside of the U.S. tend to have a much higher markup on their prices so you should expect to pay more.
  • Your Location. As with any cost of living, depending on where your car is located, you may find the cost of transmission repair higher or lower than in other areas.

Types of Transmission Repair

There are two common types of transmission repair that you can encounter when you take your car to the repair shop: a rebuilt transmission or a remanufactured transmission. They each come with different costs and have their pros and cons.

A rebuilt transmission means rebuilding the transmission with the necessary new parts - without replacing the entire unit. This is a time-consuming process, as the transmission must be taken apart, each part examined, and then put back together.

A remanufactured transmission is already built and the entire transmission is removed and replaced. This is much faster than rebuilding and you have the satisfaction of knowing that all parts have been replaced.

Having a trusted mechanic with extensive transmission knowledge can help you decide the best route for you.

Is Transmission Repair Worth it?

It is normal to feel as though you just want to ditch the car and buy a new one - especially because the transmission repair cost can seem very high. Unless your car is old and in bad shape, you may want to consider the depreciation of a new vehicle, the monthly car payments you are sure to have, additional insurance costs, and so forth.

When you break it down like that, it is easier to see that getting through this one hefty, unexpected cost can actually keep your car running longer and stronger - without all the added expenses of a new car.

Review your options, learn about any warranties that come with your transmission repair cost, and make your decision.

To learn more about transmission repair from a trusted source, contact Circle D Transmission at (713) 895-7019.

Circle D Transmission Now Offers High Horsepower 6L80 and 6L90 Parts

Performance TransmissionCircle D Transmission is excited to announce that we are now offering High Horsepower 6L80 (6L80e) and 6L90 (6L90e) Performance Transmission Rebuild Kits and Parts. We offer FREE UPS Domestic Ground Shipping. Most orders ship the same day if ordered by 12pm, Central Standard Time, Monday through Friday.

Click here for more information about kits and parts

CDT’s Kits are available in multiple horsepower levels:

  • 6L80 (6L80e) Level 2 Rebuild Kit rated up to 550 RWHP

  • 6L80 (6L80e) Level 3 Rebuild Kit rated up to 750 RWHP

  • 6L80 (6L80e) Level 4 Rebuild Kit rated up to 1000 RWHP

  • 6L90 (6L90e) Level 2 Rebuild Kit rated up to 600 RWHP

  • 6L90 (6L90e) Level 3 Rebuild Kit rated up to 750 RWHP

  • 6L90 (6L90e) Level 4 Rebuild Kit rated up to 1100 RWHP

CDT began the journey of taking the factory GM transmission and transforming it so that it could handle the horsepower revolution present today when we purchased a Gen 5 Camaro for R&D. Along the way, there were many requests from fellow horsepower junkies to purchase CDT’s revolutionary Performance Rebuild Kits for the 6L80 (6L80e) & 6L90 (6L90e.)

These Rebuild Kits have the necessary components to dial in your transmission rebuild correctly - from hydraulics to clutch clearances to transmission end-play. Included in each Kit is valuable information pertaining to transmission assembly tips and detailed CDT rebuild instructions. These kits pick up where GM left off in terms of strengthening the OE transmission to handle the ever-increasing horsepower levels of today’s vehicles.

Besides offering the complete rebuild kits for the 6L80 (6L80e) and 6L90 (6L90e) we also offer individual components. One of our more popular parts is the 4140 H.T.S.R. (Heat Treated and Stress Relieved) Billet Reinforced Output Carrier – also known as the Billet Planetary. It includes a 4140 billet steel drive to strengthen the spline area. The drive plate is milled and contoured to the planetary housing to eliminate any possible separation under a load. This is a drop-in part for vehicles producing over 750 RWHP and also for Nitrous and/or Heavy Vehicles including trucks, SUV’s and CTS-V’s.

Learn more:

Another popular option is the Billet Shaft, Hub and 4-5-6 Clutch Kit for both the 6L80 (6L80e) and the 6L90 (6L90e.) The billet intermediate shaft is made to our specifications to address the weak stock shaft issue, is precision machined from 300M alloy steel and is heat-treated to add strength and durability. The 4-5-6 Clutch Hub is also manufactured to address the weakness in the stock hub while at the same time it improves lubrication to the 4-5-6 clutch module. It is made from 4140 H.T.S.R. billet steel. Our 4-5-6 clutch modules increase apply area and the G3® friction material is formulated to maximize heat resistance and minimize wear to the clutch module.

Understanding the Process & Cost Behind Transmission Repair

Transmission repair

Do you suspect that your vehicle has a major transmission issue? Are you dreading having to research transmission repair options? And, what about how much money the transmission repair is going to cost? Are you also wondering if your car or truck’s transmission is even worth repairing?

If you’re asking yourself those questions, you are not alone and we understand your possible stress and confusion. After all, transmission repair is a costly investment that you are making into your vehicle. Transmission repair is incredibly complex and requires a proper diagnosis from the get-go or else you could open yourself up to huge levels of frustration.

At Circle D Transmission, we are here to guide you through the transmission repair process so that you can make an informed decision. In the end, with the correct information and knowledge, you’ll be able to understand your options and the associated costs behind transmission repair so that you can make a decision that is best for your situation.

So, let’s break down the different repair options when it comes to transmission repair. There are two main options nowadays if your transmission requires rebuilding. You can have your transmission rebuilt by a local facility or you can replace it with a remanufactured transmission. While either of these options can provide you with a quality transmission, there are pros and cons to each.

Let’s start by mentioning the benefits of each option.

One benefit of rebuilding your transmission is that we are able to upgrade parts that frequently fail with high mileage and/or have aftermarket updates. At Circle D Transmission we have decades of experience rebuilding transmissions and we can ward off future issues by replacing/upgrading parts that are known to fail. A benefit of replacing with a remanufactured transmission is that the turn-around-time is typically much faster than rebuilding since the transmission that we purchase is already built and waiting on the shelf of one of our suppliers.

Now, let’s move on to discuss warranties. When we rebuild your transmission here at Circle D Transmission, the typical warranty that we offer is 2 years or 24,000 miles, whichever comes first. Warranty issues must be brought back to us at our location in Houston, Texas. If you replace it with a remanufactured unit, the warranty can go up to 3 years or 100,000 miles, whichever comes first. Remanufactured transmissions typically offer a nationwide warranty. Both warranties typically cover parts and labor. So, if you are planning to keep your vehicle for many years and/or travel out of the greater Houston area often, you may want to consider a remanufactured transmission for greater peace of mind.

You also need to consider if your vehicle’s transmission is worth fixing. When clients bring this valid question up to us, we urge them to assess the rest of the vehicle. If the rest of the vehicle is in good working order then it probably makes sense to invest in the transmission and have it rebuilt or replaced. If you go to trade in a vehicle with a malfunctioning transmission, you’re going to take a fairly substantial hit in the value of the vehicle -- one that is likely equal to the cost of repairing the transmission. Other costs associated with purchasing a new vehicle are:

  • Depreciation of the new vehicle

  • Unless you pay cash, you will have a monthly payment with finance charges

  • Taxes and fees paid to purchase the new vehicle

  • Additional insurance costs on the new vehicle

Are you thinking about buying a used vehicle instead, so that you don’t have to take out as large of a loan and can factor in less loss due to depreciation? Think again... you could possibly be buying someone else’s problems... including a malfunctioning transmission in the near future. By keeping your current vehicle, you know the service history, so you’re less likely to have a surprise.

If you allow Circle D Transmission the opportunity to earn your trust, we assure you that we will provide you with ample information upfront so that you can make a decision that makes sense for you now and years down the road!

So how much does it cost to repair or replace a transmission? The average cost to rebuild or replace with a remanufactured unit is $3,000 - $5,000.

For an estimate, call 713-895-7019 or click here to schedule an appointment.

True Transmission Experts at Circle D Transmission

Do you know what it means to be a true transmission expert? To us it means specializing in one area and working every day to remain as an expert. At Circle D Transmission we specialize in transmission repair - we don't repair brakes, engines, air conditioners, or any maintenance services other than transmissions. What that means to YOU is that we are experts in our field. Our highly trained transmission technicians are able to hone in and become transmission experts with today's sophisticated transmission units. So, if you suspect that your transmission is giving you an issue, go see a transmission specialist - one that is an expert and has the experience to diagnose your transmission properly. Call us at 713-895-7019 or send us an email to:

Frequent Transmission Issues

On a daily basis we get phone calls from clients describing the issues noted below. If your vehcicle is experiencing any of these issues your best bet is to bring it to Circle D Transmission so that we can complete an initial evaluation and address any potential transmission issues. 

1 - I am pressing the gas, but the RPMS are going up and my vehicle is not moving like normal - my transmission seems to be slipping


2 - I hear a strange noise that seems to be coming from my transmission - especially when it changes gears

3 - I notice a leak where I park my car 

4 - My check engine light is on and my car seems to be stuck in one gear

If you're experiencing any of the issues above please call Circle D Transmission at 713-895-7019 or email us at:



Rebuild my Transmission or replace with a Remanufactured Transmission?

At Circle D Transmission, we pride ourselves in the proper diagnosis of your transmission problem. If we determine that your transmission requires rebuilding or replacing, you have more options these days. There are times that it makes more sense to replace your transmission with a remanufactured unit instead of us rebuilding it. For instance, severe hard part damage, a lack of available parts, or a longer / nation-wide warranty, are all things to consider when making the decision to replace your transmission. At Circle D Transmission, we approach every vehicle on an individual basis and look for the best solution for you and your situation. If you suspect that you're having transmission issues, the first step is to bring it to us for a professional diagnosis. Call us at 713-895-7019 or email us at: 

Circle D Transmission - Houston's Top Choice for Professional Diagnosis and Repairs
Circle D Transmission, located in Houston, Texas has been helping people just like you since 1976 with their transmission repair needs. We are still owned and operated by the same family for over 4 decades. So, when you begin noticing a problem with the transmission in your vehicle, we know what you’re thinking...How much is this going to cost me and how long will I be without my vehicle? We know that bringing your vehicle to a transmission repair shop is...