Before concluding that the negative signs of your vehicle shifting are bad transmission solenoid symptoms, there are some important things to look out for.
Automatic vehicles don’t make shifts by chance. Some vital components function and interact together to make a proper automatic gear shifting, and transmission solenoid is one.
So, unless your vehicle has a faulty transmission control solenoid, you may never hear of this vital component of the vehicle.
Before we dive into how you will know when this part of your vehicle is getting bad or requires the attention of a mechanic, let’s get a clear understanding of what a solenoid is and its function in a vehicle.
What Is a Transmission Solenoid?
A transmission solenoid is an electro-hydraulic valve used in automatic transmissions to control the flow of transmission fluid and regulate gear shifts.
Each solenoid receives electrical signals from the transmission control module (TCM) or engine control unit (ECU), telling it when to open or close based on inputs like throttle position, engine speed, and load.
What does a transmission control solenoid do?
A shift solenoid is a clever little unit buried inside your car’s transmission, and it’s got a pretty important job.
It controls the flow of hydraulic fluid, which is the lifeblood of an automatic transmission. This fluid pressure makes your gears engage and shift smoothly as you drive.
Here’s how it works: your car’s computer monitors speed, throttle position, engine load and a ton of other data. Based on all that data, it tells the shift solenoids when to open or close.
This directs hydraulic pressure to specific gears, ensuring your transmission knows precisely when to shift and into what gear. It’s the unsung hero of smooth driving.
Now, most modern cars have a team of these solenoids working together to handle different gears.
But when one starts to act up, it’s like the whole team loses its rhythm. You could experience jerky shifting, getting stuck in a single gear, or even a no-drive condition. Not fun.
The good news? Shift solenoids are relatively easy to diagnose and fix compared to other transmission issues.
Regular maintenance, like keeping your transmission fluid clean and topped up, goes a long way in keeping these little guys in good working order. When they’re doing their thing, you’ll never even notice them. But when they don’t— you’ll really miss these little guys.
Bad transmission solenoid symptoms
When a shift solenoid starts to misbehave, your transmission won’t be shy about letting you know. The symptoms can range from annoying quirks to serious issues that leave you stranded. Here are the most common red flags to watch for:
#1. Delayed Gear Engagement.
Ever shifted into drive or reverse and felt like your car was thinking about it for a moment too long? That’s a classic sign of a bad shift solenoid. The hydraulic fluid isn’t getting to where it needs to go quickly enough, leaving you waiting and wondering.
#2. Stuck in One Gear.
If your car suddenly decides it’s happy staying in first gear—or worse, it won’t come out of neutral—you’re likely dealing with a failed solenoid. It’s like the transmission has lost its ability to switch gears entirely.
#3. Erratic or Harsh Shifting.
Does your car lurch forward like it’s got something to prove every time it shifts? Or maybe the shifts are so jerky, you feel like you’re in a go-kart. Either way, inconsistent or rough shifting is a telltale sign your solenoid isn’t playing ball.
#4. Gear Slippage.
You’re cruising along, and suddenly, the transmission slips out of gear, leaving you revving and going nowhere. Not only is it annoying, but it’s also dangerous—especially in traffic.
#5. Check Engine Light.
Ah, the dreaded dash disco. A faulty shift solenoid often triggers the check engine light, especially in modern cars.
Grab an OBD-II scanner, and you’ll likely see a transmission-related code pointing to the solenoid. Here’s the common ones – P0750, P0751, P0752, P0755, P0756, P0757, P0760, P0761, P0762, P076, P0770.
#6. Poor Fuel Economy.
A bad solenoid can throw your transmission’s timing off, making the engine work harder than it should. The result? You’re burning more gas than usual—and feeling the pinch at the pump.
#7. Transmission Overheating.
Struggling to shift properly means your transmission has to work overtime. That can lead to overheating, which is a slippery slope toward more costly repairs if ignored.
If you’ve noticed any of these symptoms, it’s time to take action. Ignoring a failing shift solenoid won’t just make your drive unpleasant—it can lead to bigger, spender problems down the road. Catch it early, and you’ll save yourself a lot of hassle and cash.
What Causes Transmission Solenoid Failure?
Several factors can cause a transmission solenoid to malfunction:
#1. Contaminated or Low Transmission Fluid.
Dirty or low fluid prevents the solenoid from operating correctly, as debris may block the solenoid valve or restrict fluid flow.
#2. Electrical Issues.
The solenoid relies on proper electrical signals. Damaged wiring, loose connections, or a failing ECU/TCM can cause miscommunication or voltage drop.
#3. Overheating.
Excessive heat can burn out the solenoid coil or degrade internal seals, especially if the vehicle is under heavy loads or poor driving conditions.
#4. Normal Wear and Tear.
Like any mechanical part, solenoids can simply wear out over time—especially in high-mileage vehicles or transmissions that have not been regularly maintained.
Pro tip: Always use the manufacturer-recommended transmission fluid to avoid chemical incompatibilities that may harm solenoid seals.
Diagnosis Bad transmission solenoid
Initially, we need to determine if the issue is caused by wiring, shift solenoid, TCM issue, or mechanical problem. You need to read and research the trouble codes to fully understand the problem before beginning troubleshooting.
If the trouble codes indicate that it is stuck or an electrical issue, you most likely have a wiring or shift solenoid issue, so you would need to inspect and perform tests on the shift solenoids.
For many shift solenoid related codes, the resolution may just be a transmission fluid swap or doing a transmission flush. Generally, a transmission fluid swap is not particularly costly, so it’s well worth it.
When it comes to diagnosing issues regarding the shift solenoid, utilizing a diagnostic scanner is crucial.
Below is a list of how to perform the diagnostics with a scanner:
- Find a transmission wiring diagram for your transmission.
- Find out which pins on the wiring harness go to the affected shift solenoid.
- Loosen the transmission wiring plug on the transmission.
- Pull out the OBD2 scanner and start the output test for the affected shift solenoid.
- Within the output test, use the multimeter to see if you are able to get 12 volts and ground at the plug on the transmission at the correct pin related to the shift solenoid.
If you are not getting both 12 volts and ground, you may have a wiring issue or the TCM may be faulty.
If you are getting 12 volts and ground and the shifted solenoid trouble code keeps reappearing after you have cleared the code, you may have a faulty shift solenoid.
Common Shift Solenoid-Related OBD-II Codes
P0750: Shift Solenoid A Malfunction
- Indicates an issue with the “A” solenoid, which could be electrical or mechanical.
P0751: Shift Solenoid A Performance/Stuck Off
- Suggests the “A” solenoid isn’t operating as expected or is stuck in the “off” position.
P0752: Shift Solenoid A Stuck On
- Means the “A” solenoid is stuck in the “on” position, causing improper fluid flow.
P0755: Shift Solenoid B Malfunction
- Points to a problem with the “B” solenoid, similar to the P0750 code but for the next solenoid in sequence.
P0756: Shift Solenoid B Performance/Stuck Off
- Indicates the “B” solenoid is stuck off or not working as it should.
P0757: Shift Solenoid B Stuck On
- The “B” solenoid is stuck in the “on” position, disrupting hydraulic pressure.
P0760: Shift Solenoid C Malfunction
- Identifies an issue with the “C” solenoid, either electrical or mechanical.
P0761: Shift Solenoid C Performance/Stuck Off
- The “C” solenoid is not engaging properly or is stuck in the “off” position.
P0762: Shift Solenoid C Stuck On
- Means the “C” solenoid is stuck in the “on” position, causing shifting problems.
P0765: Shift Solenoid D Malfunction
- Signals a problem with the “D” solenoid, typically part of a multi-solenoid system.
P0770: Shift Solenoid E Malfunction
- Refers to an issue with the “E” solenoid, often found in more complex transmission systems.
How to Replace a Shift Solenoid?
Replacing a shift solenoid isn’t the most complicated job, but it does require some patience and basic tools. Here’s a step-by-step guide to help you tackle the job:
Step 1: Tools and Supplies.
Before you dive in, make sure you’ve got everything you need:
- A new shift solenoid (check your car’s make and model for the correct part).
- Transmission fluid (you’ll need to replace some).
- Transmission filter and possibly a pan gasket.
- Socket set and wrenches.
- Screwdrivers.
- A drain pan.
- Rags or shop towels.
- Safety gloves and glasses.
Step 2: Locate the Solenoid.
The shift solenoids are inside the transmission pan, but consult your car’s repair manual to be sure. Some vehicles may require you to also remove parts of the valve body, which is a bigger job.
Step 3: Drain the Transmission Fluid.
Place your drain pan under the transmission and carefully remove the drain plug to let the fluid out.
If your car doesn’t have a drain plug, you’ll need to loosen the transmission pan bolts slowly to let the fluid drain. It’s messy, so be prepared with shop towels and brake cleaner.
Step 4: Remove the Transmission Pan.
Once the fluid has drained, remove the bolts securing the transmission pan. Be ready for a little extra fluid to spill out when you pull the pan off.
Set the pan and gasket aside—you’ll inspect and clean these later (pan gaskets should ideally be replaced). Now go ahead and remove the filter, you’ll fit a new one later.
Step 5: Identify the Faulty Solenoid.
With the pan and filter removed, you’ll see the valve body and the solenoids. Use your car’s repair manual or online resources to identify the faulty solenoid. It is best to double-check that you have identified the faulty one by checking its resistance with a multimeter.
Step 6: Remove the Bad Solenoid.
Unplug the electrical connector on the solenoid, then carefully unbolt or unclip it from the valve body. Be gentle to avoid damaging surrounding components.
Step 7: Install the New Solenoid.
Position the new solenoid in place, secure it with bolts or clips, and reconnect the electrical connector. Double-check that it’s seated correctly and firmly connected.
Step 8: Reinstall the Filter And Pan.
Fit the new filter, clean the transmission pan thoroughly, and inspect the gasket for damage. If the gasket is worn or cracked, replace it. Reinstall the pan, tightening the bolts in a crisscross pattern to ensure an even seal.
Step 9: Refill the Transmission Fluid.
Using a funnel, add fresh transmission fluid to the proper level. Start the car, and without moving the vehicle, move the selector to D, then to R, then to N, then to P and repeat a few times.
Now, while in P and the engine still running, check the fluid level, be sure you are checking the hot position on the transmission dipstick (if fitted) and top it off as needed.
Step 10: Test Drive.
Take your car for a short test drive to ensure everything works smoothly. Pay attention to gear shifts and listen for any unusual noises. Check the fluid level once again and inspect for leaks under the vehicle. If all feels right, you’re good to go!
Tips:
- Work in a clean, well-lit space to avoid contaminating the transmission.
- Use the correct type of transmission fluid for your car.
- If you’re unsure at any step, consult a repair manual or get help from a professional.
Replacing a shift solenoid might seem intimidating, but it’s a pretty simple process.
How Do You Test a Shift Solenoid?
Testing a transmission solenoid to confirm it’s a problem starts with pulling the corresponding solenoid that threw a code. You can then test it with a multimeter using the following steps.
- Step 1: Drain the transmission fluid, and inspect it for color and contamination.
- Step 2: Remove all the bolts holding the transmission oil pan in place. You might have to lightly tap it with a rubber mallet to remove the oil pan. Be careful not to damage the gasket or bend the metal edges.
- Step 3: Find the solenoids; they’re usually right next to the transmission oil filter.
- Step 4: Remove the transmission filter before pulling the suspect shift solenoid(s).
- Step 5: Set your multimeter to read Ohms.
- Step 6: Connect the ground wire/clip of the meter to the body ground of the solenoid.
- Step 7: Connect the red lead on the multimeter to the power connection of the shift solenoid. It should give you a reading between 12 to 28 Ohms.
- Step 8: Set the multimeter to measure amperage. It should give you reading around 0.75 to 1.2 Amps. It should also make a clicking sound as the solenoid activates.
If it gives you numbers that are grossly out of range, then the solenoid itself is bad. If the solenoid tests in range, then there is likely another transmission fault affecting solenoid performance. The most likely culprit is a problem with the TCM.
FAQs.
Q: Can you drive with a bad transmission solenoid?
Yes, you can drive a vehicle with a bad transmission solenoid. Nevertheless, you should keep in mind that the problem may escalate into an expensive repair if not taken care of as soon as possible.
Also, since solenoids are in charge of controlling gear shifting and vehicle acceleration, the driver will experience difficulty as he drives without fixing the solenoid fault.
Q: Can you start a car with a bad solenoid?
Unless your vehicle has a bad starter solenoid, you can still start your car. Faulty starter solenoids affect a vehicle by causing it to start on its own without the driver turning the key to start the vehicle.
Either your vehicle is having a problem with the starter solenoid or the transmission solenoid, you should address the problem without delay.
Q: How much does it cost to replace the shift solenoid?
To replace one shift solenoid can cost between $100 to $350, making the pack of a shift solenoid cost about $400 to 700 dollars, as well as the cost for labor, the transmission fluid, parts, and filter.
You should also know that transmission solenoid repair costs may vary depending on the model of the transmission as well as the vehicle model. Some vehicles only permit the replacement of the whole pack instead of one or two faulty solenoids.
Sometimes, you may have to replace the complete body of the valve, which may be expensive. Nevertheless, always change the filter and transmission fluid whenever you replace a solenoid, the body of the valve, or the complete pack.
Q: How long does it take to change a transmission solenoid?
Changing a transmission solenoid takes about 2 to 4 hours, which makes it easier to calculate the labor cost for fixing this part of your vehicle.
So far, you’re paying per hour; you can deduce what the total cost will be by adding the cost of hours it’ll take to the cost of the part replacement.
Q: Will a bad shift solenoid always throw a code?
When you diagnose your vehicle for solenoid problems using a scanner, you’ll always see a trouble code. This trouble code may persist even after troubleshooting the engine, and this means the fault is yet to be fixed.
If you tried troubleshooting it yourself and the problem persists, you should call a mechanic or a transmission expert to examine the trouble code and look into the vehicle.
Final Words
Bad transmission solenoid symptoms manifest in different ways. As mentioned, you may experience difficulty in downshifting, as well as unusual gear shifting either upwards or downwards.
Your gear may also get stuck if your vehicle solenoid gets faulty. When you start seeing these signs, it means your vehicle solenoid requires attention, and you shouldn’t hesitate to fix the problem.