Trailblazer Shift Solenoid Symptoms: What are DIY Solutions?

Trailblazer shift solenoid symptoms will help you know when your solenoid is faulty. Identifying these symptoms is important, so you can fix the solenoid quickly and prevent further complications.

Trailblazer Shift Solenoid

In this article, we discuss all the symptoms of a bad or faulty shift solenoid and the solutions.

What Causes Faulty Shift Solenoids?

The causes of faulty shift solenoids range from wear and tear to dirty transmission fluids. The problem can also arise due to electrical wiring issues or contamination of the solenoid with dirt and debris. Solenoids can also fail when they’re at the end of their lifespan.


Wear and Tear

Like any car component, shift solenoids undergo wear and tear over time. However, most times, it’s the associated components that undergo wear and tear (or total damage) and cause the solenoid to fail or malfunction. Such associated parts may be the valve body or the electrical wiring. This is why regular preventive maintenance is advised for automatic vehicles.

Dirty Transmission Fluids

Dirty transmission fluids/oils are another common cause of faulty transmission solenoids. Solenoids regulate the flow and pressure of transmission oils. And so, if these fluids are contaminated, they’ll cause the solenoid to move with great difficulty.

Faulty Transmission Solenoid

As a result, it will fail. Dirt and debris in transmission oil can be quite disturbing for solenoids. This is why changing fluids regularly in automatic vehicles is advised.

Electrical Wiring Issues

Electrical wiring issues can also be the reason for a bad/faulty solenoid. A transmission shift solenoid works with an electronic module.

Issues of Electrical Wiring

The solenoid receives electro signals from this control module and activates or deactivates a gear (or gears) in your vehicle transmission. If the wires connecting to the solenoid are loose or damaged, the solenoid will be unable to send signals.

Lifespan Exceeded

A solenoid can also malfunction or fail because it has expired or exceeded its lifespan. Most car manufacturers do not have a set lifespan for the solenoid, but generally, your solenoid should last for about 50,000 miles before failing.

What Are the Signs of a Faulty Shift Solenoid?

The signs of a faulty shift solenoid include erratic gear switching, delayed switching, gear oil leaks, and slipping transmission. In some cases, the vehicle check engine light will come on. Another symptom of a failed solenoid is that the transmission refuses to engage altogether.

Hard or Delayed Gear Switching

Hard or delayed gear switching is one of the commonest symptoms of a bad trailblazer shift solenoid. When you find your gears suddenly start to switch or delay to engage, it could be due to a solenoid issue. This issue, most times, is caused by a buildup of debris and dirt in the solenoid. In this scenario, you’ll find gears responding very slowly when upshifting or downshifting.

Gear Shifts Erratically

If your gear shifts erratically, it’s a strong sign that something is wrong with your car’s transmission valve or solenoid. Ideally, your car should only change gears when you engage it. But when the solenoid goes bad, you’d find that the car changes gears randomly.

Solenoids are programmed to only open up to take in a specific volume of transmission oil for gear change before closing back up. But when the solenoid is taking in too much gear oil or isn’t closing up, your gears will shift erratically. This issue can be due to an electrical fault or a failed solenoid. It can ruin your driving experience and even cause accidents.

Leaking Transmission/Gear Oil

Leaking gear oil is another sign that something is wrong with your solenoid. Usually, this symptom indicates that the valve in which the solenoid is located is damaged or leaking. As a result, fluid is leaking out of the system.

If left unattended, this symptom can lead to further complications like low transmission oil and total failure of your transmission system. Your car might even be forced to enter into limp mode.

Engine Warning Light

The check engine warning light can also be a clear indicator of a bad solenoid. Most automatic transmission vehicles come with a warning light that flashes trouble codes. If your car has this feature, you will find that it flashes a specific trouble code, P0750, when your solenoids are bad.

The P0750 OBD code is the official trouble code that represents a solenoid malfunction. To read this code, you may need an OB2 scanner. However, some cars have a separate warning light for the transmission system. If this light comes on, check important parts of your transmission system, like the solenoid, or seek a professional to help you decipher the warning code.

Slipping Transmission

Slipping transmission is another giveaway sign of a bad solenoid. Your transmission is said to be slipping when it doesn’t stay in a particular gear as you drive (slips to a lower gear). In manual transmission vehicles, a failed clutch would most likely be responsible for this problem. For automatic vehicles, however, it’s the shift solenoid.

Transmission Doesn’t Engage

If your transmission doesn’t engage at all, you most likely have a solenoid problem. Usually, this symptom is noticed when the solenoid is outrightly damaged and will always trigger a warning light (if you have one). Even driving becomes impossible at this point, leaving you no option but to replace the solenoid.

How To Fix Trailblazer Shift Solenoid Symptoms

To fix trailblazer shift solenoid symptoms, you have to test the solenoid to confirm if it’s bad or just faulty. Next, you’d have to replace the old solenoid with a new one. Sometimes, the issue may not call for replacement, cleaning the solenoid may be enough.

Test the Solenoid

The first thing to do when trying to fix the solenoid’s symptoms is to test the solenoid. Your job is to determine, through an electrical test, if the solenoid is opening and closing as it should. To do this test, you’ll need a multimeter.

Testing Electrical Solenoid

First, set your multimeter to ohms, then disconnect your solenoid from the electrical wires and ground it. Now, use your multimeter probes to touch the solenoid terminals. If the reading is too high or too low, the solenoid is faulty and needs to be replaced. The generally accepted value for healthy solenoid readings is around 12 ohms.

You can find the solenoid in the valve body of your vehicle transmission system. In some cars, you can spot them without removing the valve body, but in some other cars, they’re only accessible after removing the valve body.

Clean or Flush the Solenoid

Cleaning or flushing the solenoid can be effective for blocked or contaminated solenoids. To carry out this cleaning, you’ll first have to remove the solenoid, then use a wire brush to wipe off the dirt. Next, gently apply a brake cleaner and gently tap the solenoid onto a cloth or towel to force out the dust inside.

Replace the Solenoid

Replacing the solenoid is the final solution if you test your solenoids and they turn out to be bad or damaged. Sometimes you may only need to replace the transmission filter, not the actual solenoid. This is why it’s important to test solenoids before deciding to replace them.

Replacing Solenoid in Vehicle

Note that to replace your solenoid, you’ll need some basic tools, including spanners, pliers, a wrench, and a car jack.

How To Replace the Solenoid in Your Vehicle

To replace the solenoid in your vehicle, first you need to locate the transmission system and then find the solenoid valve. Next, you must drain the transmission oil, then unbolt the solenoid and disconnect its wires. Finally, remove the old solenoid and install the new one.

Step 1: Get a New Solenoid

Get a brand new solenoid from an automobile parts store. You can ask a technician to run a quick diagnostics to verify if your car’s solenoid is actually bad. Now, park your car in a safe spot, preferably a well-ventilated garage with even flooring.

Step 2: Raise Your Car

Turn off the ignition and apply wheel blocks to the back of the tires to prevent them from rolling. Now, use a jack to raise the front end of your car.

Step 3: Drain the Oil Compartment

Crawl under your car and try to locate the transmission in the driver’s side of the vehicle. Take care to note the oil compartment and place a pan under it. Loosen the bolts keeping the oil compartment in place and collect the oil draining out in the pan.

Step 4: Locate Your Solenoid

Now that the transmission oil is out of the way, locate the solenoid housing area. You should find the solenoids after or before opening up the valve body (depending on your car brand/model).

Checking Transmission Oil

Since most automatic transmission systems have two to five shift solenoids, use the color codes to know which one matches the replacement solenoid you bought. Otherwise, you have to replace the entire assembly.

Step 5: Remove the Solenoid

Once you have spotted the bad solenoid(s), find the mounting bolts and undo them using a wrench. Next, unplug the wire from the solenoid. Then, use a flathead screwdriver to pull out the solenoid and gasket from the transmission.

Step 6: Clean the Solenoid

Clean the solenoid mounting surface with a wire brush and brake cleaner. Also, apply some transmission oil to the replacement solenoid to ensure proper lubrication. Now, put the new solenoid in place of the old one. Make sure to press it in until you hear a clicking sound.

Step 7: Mount the Solenoid

Reinstall the connecting wires and mounting bolts. Clean the transmission oil container with a clean rag, making sure to remove all rust and dust. After that, reinstall the container and any mounting bolts you previously removed. Also, remember to reinstall a new gasket for the solenoid.

Once you’re done with all that, crawl out from under your vehicle and lower your car. Refill your car with new transmission oil. Allow the gaskets to set for a few minutes, then test drive your car.


How Much Will You Spend to Replace a Solenoid?

To replace a solenoid you will spend anywhere from $150 to $300. The actual solenoid replacement cost will depend on the model of your vehicle and the extra charges for labor. Replacing a pack of solenoids can cost up to $700.

Is It Possible To Drive With a Faulty Transmission Solenoid?

Yes, it is possible to drive with a faulty transmission solenoid. However, you will have a terrible driving experience, and in some cases, your car may even go into limbo. It’s best to fix solenoid problems as soon as you notice them to avoid worse complications.


A bad/faulty shift solenoid in your car can ruin your driving experience, no matter the car’s make or model. In this article, we’ve discussed the causes, symptoms, and solutions to this problem. Let’s go over the major points once more:

  • Shift solenoids become bad or faulty due to wear and tear, electrical wiring problems, dirt and debris contamination, or old age.
  • The symptoms of a bad solenoid include hard gear shifting, delayed shifting, gear slipping, leaking transmission/gear oil, and a P0750 error code on the engine warning light.
  • To fix this problem, you should first test the solenoid to verify whether it’s faulty. Next, carry out a cleaning/flushing operation, or replace it entirely.
  • You can replace a single solenoid if you are sure it’s the only bad one in your car, or just replace the entire assembly altogether.

Testing and replacing the solenoid in your car can be tricky, so get an auto mechanic to help you out if you’re not well-experienced in DIY operations.

Rate this post
Ran When Parked