Most of the vehicles we drive are either front-wheel or rear-wheel drive. But, if you own a larger vehicle such as an SUV or a truck, then you’ll have the option to choose between two-wheel and four-wheel drive. For you to switch from 2-Wheel to 4-Wheel drive successfully, your car must have a functional transfer case control module. Now, just like other components, the transfer case can sometimes fail to make it hard for your car to switch to four-wheel drive. If this is what you’re experiencing, then you must learn the symptoms of a bad transfer case control module.
Just as we’ve mentioned earlier, the transfer case control module is responsible for regulating the transfer of power to the front and rear axles to give your truck or SUV superior traction to traverse on rough challenging terrains.
But, just like other mechanical components, the transfer case can sometimes fail. In the event of failure, you’re likely to notice several symptoms that range from strange noises, and loss of power to difficulty shifting to four-wheel drive. So, in this guide, we’ll discuss what a transfer case is, how it works, signs of decay and how to fix and replace it.
What Is a Transfer Case?
A transfer case is a very specialized component that’s fitted in all 4WD and AWD vehicles. Since such vehicles rely on both the front and rear axles to move, a transfer case is needed to send power from the engine to the front and rear axles to power the four wheels. In most cases, the transfer case is located between the transmission and the differential.
Now, there are many different types of 4WD and AWD configurations when it comes to trucks and SUVs. To guarantee a perfect working unison, a different type of transfer case is needed in each configuration. However, there are two main transfer cases that are utilized in most trucks and SUVs. These are part-time and full-time transfer cases.
Full-time transfer cases are mostly utilized in vehicles that are always in 4WD mode. So, if your truck or SUV is always in 4WD when driving on pavements on on-road, then you need a full-time transfer case. This type of transfer case is usually simple, convenient, and easy to engage as you don’t need to stop the vehicle just to change the gears.
A part-time transfer case, on the other hand, is utilized on vehicles that are driven off-road. This type of transfer case consists of many complex systems that work in unison to allow the vehicle to run in different drive modes. Since this type of transfer case can be disengaged when not needed, it has minimal wear and tears on the gears.
Now, when choosing a transfer case, it’s important to consider where and how you’re planning to use it. That’s because transfer cases come in different sizes and configurations. While some use chains, others use hydraulics and others use gears.
Also, you need to understand that transfer cases in 4WD and AWD vehicles are just one part of a lengthy and complex drivechain system that powers your car. Here, power from the engine is transferred to the transmission and then to the rest of the components that consist of driveshafts, differential, transfer case, drive axles, and wheels.
How Does a Transfer Case Work?
Now that you’re aware of what a transfer case control module (TCCM) is, we will now switch our focus to discuss how exactly this system works. At least by understanding how this complex system work, you’ll be able to understand which symptoms to look out for while driving.
Earlier on, we mentioned the main purpose of a TCCM is to assist your vehicle to switch from 4WD to AWD when driving. Although we touched a little bit on how it works, here’s a broader perspective on how a TCCM works.
First, a transfer case can be chain-driven (modern models) or gear-driven (older units). For a chain-driven transfer case, the chains transfer power from the input shafts attached to the gearbox to the output shafts attached to the differential.
The output shafts from the differential have two splices that are attached to the front and rear axles. So, when you engage the 4WD when driving, the TCCM first reads the speed of the car via the speed sensors to decide whether to make a shift to 4WD or whether to disengage it in case you need to turn it off.
Something else about the transfer case is that it has two high and low ratios to choose from. The high ratio is essential when you’re driving on-road while the low ratio is essential when towing heavy equipment or when you’re off-roading.
How Do I Know I Have a Failing Transfer Case?
Although they’re designed to last long, TCCM can sometimes go bad just like the rest of your car’s mechanical parts. But, for you to fix the problem, you need to know whether the underlying problem is truly caused by the transfer case. So, how can you tell you have a bad transfer case?
- First, you should pay attention to strange noises such as whining and any transfer case grinding noise. In most cases, these sounds signal damaged chains and gears inside the transfer case.
- If you suddenly see a 4WD service message, then this is another clear sign of a failing TCCM. Although the message can be a reminder of your regular 4WD servicing, it can sometimes signal a faulty or failing transfer case.
- If your vehicle is having trouble shifting gears, then this is another clear sign of a malfunctioning transfer case.
- Other times, the problem can be engine hesitation when you accelerate. In most cases, this indicates a failing transfer case where it’s sending the wrong signals to the transmission.
- Lastly, if you’re trying to engage the 4X4 system and the car isn’t responding, then this is a clear sign of a struggling transfer case.
How Can I Prevent My Transfer Case from Getting Damaged?
We’ve already mentioned the main task of the transfer case is to transfer power to the front and rear axles of your vehicle. Since it plays a vital role in your car, regular maintenance is needed to prevent this vital component from ever going bad.
One of the ways you can prevent the transfer case from going bad is to drain its fluid and replace it with something fresh and young. Fresh fluid is needed to cool and lubricate the gears, bearings, and shafts. Since the transfer case doesn’t have a filter, the system is highly exposed to bits of metal and clutch materials that can scratch the gears, chains, and bearings to cause accelerated wear.
Secondly, if you do a lot of off-roading or towing heavy loads, it’s important that you service the transfer case regularly. You should also perform regular checkups for any signs of leakage or buildup of debris within the system.
Lastly, the transfer case is a very complex system. So, to avoid any further damage, it’s recommended that you hire an expert mechanic to inspect and repair this system.
What Controls My Transfer Case?
Now, we’ve learned what a transfer case is, how it works, how to detect whether it’s damaged and how to prevent it from going bad. Before we discuss common symptoms of damaged TCCM, let’s first look at what exactly controls a transfer case.
First, the TCCM is tasked to send signals to the transfer case to notify it when to switch from 2WD to 4WD depending on your demands. It also tells the transfer case what ratio to use (low or high) depending on whether you’re driving on-road or off-road.
So, what controls a transfer case? Now, in most cases, a transfer case can either be chain-driven or gear-driven. Chain-driven transfer cases are lighter, quieter, and mostly used on modern vehicles. On the other hand, gear-driven transfer cases are noisier, heavier, and very strong making them ideal for heavy-duty applications.
Symptoms of a Failing Transfer Case Control Module
The transfer case is among those components that are predicted to last the lifespan of your car. However, depending on various internal and external factors, this vital component can sometimes become susceptible to damage.
In the event of damage, there are those notable signs you’re likely to identify. So, in this section, we’re going to discuss what happens when a transfer case goes bad.
1. Weird Griding, Humming & Growling Sounds
The first common sign of a struggling TCCM is weird sounds coming from under the hood. Sounds, such as grinding, humming, and growling coming from the hood indicate that something is terribly wrong. In most cases, these sounds are caused by mechanical faults such as low fluid level, loose chains, or damaged gears and bearings.
If this is exactly what you’re experiencing, then it’s wise if you hire an expert mechanic to inspect your car and fix the problem.
2. Issues Shifting Gears
Another common symptom of a failing TCCM is difficulty shifting between the gears. If this is what you’re experiencing, then the problem can be due to a faulty transfer case or a low fluid level.
3. Difficulty Engaging and Disengaging 4WD
Are you having trouble engaging or disengaging the 4WD? Well, the problem is not anything else but a malfunctioning transfer case control module. But, other than the transfer case, the problem can be caused by an electrical fault in the control system or a failing shift mechanism.
4. Formation of Greasy Puddle Under the Transfer Case
Are you seeing puddles of grease or oil under the car, especially below the transfer case location? If yes, then there’s possible oil leakage in the TCCM. To confirm whether the leakage is coming from the TCCM, you need to jack up the car to perform a visual inspection.
But other than seeing puddles of oil under the car, another way to detect possible leakage in the TCCM is when you notice the transmission fluid is getting dangerously low even after refilling it.
5. Difficulty Maintaining 4WD
Another sign that signals a failing TCCM is difficulty staying in 4WD. Although the main culprit is a faulty transfer case control module, there are other problems that can reveal similar symptoms such as a malfunctioning driveshaft or a failing differential.
6. 4WD Alert Messages
While some vehicles reveal a “Service 4WD” message on the dashboard, others show a pop-up message on the DCI (Driver Information Center) while others illuminate the 4WD light until the problem is corrected.
If this is what you’re seeing, then it simply means the TCCM is not performing optimally. Although this service message will go away when you turn the engine off and then on, this symptom is a clear sign of a struggling TCCM. So, in this case, you need to learn how to reset the transfer case control module.
How to Replace a Transfer Case Control Module?
Things You’ll Need:
- A new TCCM
- Torque wrench
- Flathead and Phillips head screwdrivers
- Ratchet set
Steps to Follow
- Step One: So, start by parking your car on a level ground such as on the driveway or inside the garage.
- Step Two: Next, locate the position of the TCCM. In most cases, this component is located on the steering column on the driver’s side.
- Step Three: Once you’ve located the control module, the next step is to remove it. To take it off successfully, you need to start by disconnecting a few wire cables that connect the TCCM to the rest of the car.
Next, use a Phillips screwdriver to disconnect the TCCM from the car and a flat head screwdriver to disconnect the electrical connector.
- Step Four: With the old TCCM out of the way, it’s now time to install a new module in place. So, as usual, use the required screwdriver to bolt and screw the module in place. Reconnect the wire harness and the electrical connector using proper specifications.
- Step Five: With the new module in place, start the car to test whether it’s working perfectly. In case you hear bad transfer case sounds or any other problem that was present before, then it means there’s an underlying problem that needs immediate attention.
Frequently Asked Questions
1. How Do You Test a Transfer Case Shift Motor?
- Step One: Remove the Transfer Case Shift Motor
According to most expert mechanics, the root cause of most transfer case problems is caused by the transfer case shift motor. So, to diagnose the problem, you need to start by removing the transfer case shift motor to test it.
To remove this component, you need to jack up the car to access the underneath. Next, remove the bolts holding the motor to free it.
- Step Two: Test the Motor
To test the motor, you need to use a light test. Here, you need to locate the yellow and orange colors that connect to the motor. Set the Ohm to 200 then touch the two wires using probes. The reading should range from 2.2 to 2.7. If the reading is anything higher than this, then it means you’re dealing with a faulty motor.
- Step Three: Test with a Battery Pack
This test is to see whether the transfer case motor gear will move when power is passed through. So, here, you need to connect the multimeter leads to the car battery or a portable jumper pack. Next, connect the probes to the yellow and orange wires from the motor.
Here, the transfer case motor gear should move freely in either direction confirming that it’s okay. However, if it fails to shift, then it means the motor is faulty.
2. What Should You Do When You Notice You Have a Faulty Transfer Case?
In case you’ve identified any of the common symptoms we’ve discussed in this guide, then you should have the TCCM checked out by an expert mechanic. In most cases, your mechanic will perform an in-depth code scan to identify the exact problem.
Remember, a TCCM has many parts with sensors. Therefore, by performing a code scan, your mechanic will manage to figure out where exactly is the problem. From there, he will fix the module and mount it back in your car.
3. Where Exactly is the TCCM Located?
Now, the TCCM is located under the driver’s dashboard on the steering column. This makes it easily accessible by anyone as the connectors are directly facing you.
4. What’s the Cost of Replacing a TCCM?
Now, a TCCM can be repaired or replaced depending on the situation. In case it’s not badly damaged, then your mechanic will fix it and mount it back. In this case, you won’t spend much on repairs.
However, if the module sustains substantial mechanical damage, then you’ll have to replace it. Here, the replacement cost will range from $2,300 to upwards of $2,700 depending on the complexity of the job.
5. Can I Drive With a Damaged TCCM?
Technically yes. However, considering the importance of a transfer case in a 4WD, driving with a faulty module can cause a slew of problems. One of them is difficulty driving your car. You see, a transfer module is tasked to distribute power to the front and rear axles.
So, suppose it’s faulty or missing, then it will be impossible to utilize all four wheels when driving. Secondly, the transfer module allows the front and rear wheels to spin at the same speed. So, if it’s faulty or absent, it will be hard for you to maintain good control of your car making driving increasingly difficult.
Final Thoughts
So, there you have it. In case you’ve read up to this point, then I believe you can confidently identify the common symptoms of a failing transfer case control module. As you can see, there are quite a number of symptoms that range from shifting problems, strange noises, and oil leakage to an unresponsive 4WD system.
In most cases, it’s recommended that you drive to an auto repair shop as soon as you detect these symptoms to have your car diagnosed and fixed. Failure to have the car checked can exacerbate the problem causing severe cases such as damaged transmission, damaged gears, lack of enough oil due to leakage, and difficulty engaging 4WD when you need to.
In the end, you’ll suffer a high replacement cost as you won’t have any other alternative but to replace the transfer case control module.
