The transfer case control module plays an important role in differentiating between an all-wheel-drive (AWD) and a four-wheel drive (4WD) vehicle. A center differential can be found on AWD vehicles whereas a 4WD vehicle would come with a transfer case which would provide much-needed traction to it to traverse challenging terrain. A transfer case control module lets the driver choose whether the power will be sent to both front and rear wheels.
In event of a transfer case failure, your vehicle will display difficulties with staying in 4WD or switching between the two. In the rear situation, it affects the rear differential as both of them are connected mechanically. Thus, a driver must understand how a transfer case control module works, the signs of its decay, and how to diagnose and fix it. In this article, we will discuss at length how a transfer case control module functions.
What Is A Transfer Case Control Module?
The transfer case control module (TCCM) is in control of the general operation of a 4WD. The operation needs processing, executing, and confirming the completion of the process. It directly oversees the shifting in four-wheel-drive vehicle system operations. How does it do this?
The TCCM picks up on the truck’s speed and uses the transfer case mode to understand and determine the movements. Once the shift is completed, the TCCM will complete the process by turning on the transfer case encoder actuator. In addition, it turns off the front differential locking motor. In case the shifting is not possible, it triggers the selector switch which will blink for 45 seconds.
Location Of Transfer Case Control Module
Generally, the TCCM can be found in the control panel on the steering column on the driver’s end.
How Does The Transfer Case Control Module Work?
Before jumping into the nitty-gritty of a malfunctioning transfer case control module and its symptoms, we will briefly explain how a TCCM functions. By understanding how it operates, one can have a better understanding of all the symptoms to look out for with their TCCM while driving.
As mentioned before, the purpose of a TCCM is to assist your vehicle switch between four-wheel drive and two-wheel drive. We also talked about how it does but here’s a broader perspective.
The transfer case control module uses speed sensors to read the speed of the vehicle, processes it, and then decide whether making the shift is possible (and safe). If you are driving slow enough when the button is pressed to engage the 4WD, the module engages and lets the vehicle shift to four-wheel drive.
The same applies if you want to turn off the four-wheel-drive system. After judging the speed of your vehicle and determining whether you are moving slow enough, it will shift the car back to 2WD.
This, in reality, is a very basic explanation of what this complex component is designed to do in your vehicle. The key thing to understand and remember here is that the TCCM is responsible for shifting the vehicle between two- and four-wheel drive. Therefore, there are moving bits coordinating inside it.
Symptoms Of A Bad Transfer Case Control Module
Although they are designed to last for the service life of a vehicle, a transfer case control module may go bad. Similar to any mechanical part, when the TCCM fails, it will leave some signs to notify the owner of a problem budding within the system component. Check out the common symptoms that will let you know of a failed transfer case control module.
1. Gear Shifting Issues
A major sign of a bad transfer case control module is having problems shifting between the two gear rangers. Though the problem can be caused by a somewhat simple trigger, like damaged linkage or low fluid level, it generally indicates internal transfer case failure.
However, make sure to follow all the directions mentioned in the car’s user manual for operating the TCCM. Otherwise, you may make a wrong diagnosis. In many cases, before shifting into four-low, the car has to be stopped and transmission needs to be placed on neutral. If not, you will hear a grinding sound when trying to switch gears.
Transfer cases on old cars were controlled by the body computer. But on most modern-day vehicles, they are electrically switched. This is why the symptoms your vehicle is displaying may be different from what someone else has faced.
2. Difficulty Staying In 4WD
A transfer case that refuses to stay in 4WD is a major annoyance. The problem can be attributed to a bunch of external influences, such as a problem with the driveshaft, differential, or an internal transfer case issue.
3. 4WD Will Not Engage/Disengage
A malfunctioning transfer case control module may not be the only reason a 4WD system does not engage or disengage. The issue can stem from a faulty shift mechanism to a fault in the control system. Alternatively, there is something wrong with the interior of the transfer case.
4. Puddle Formation Under The Transfer Case’s Location
Only a leak can be the reason behind a greasy puddle build-up under your car, and the culprit can be a bad transfer case control module. Check if the leak is coming from the TCCM by raising the car on jacks and performing a visual inspection. It should be easily visible at the rear-end of the transaxle assembly or transmission.
Leaks are generally gradual so you may not see a puddle straight away. But over some time, the TCCM gets dangerously low on oil, causing overall destruction of the internal parts. This happens slower on an automatic transmission as transfer cases come with an oil pump – there are none on a manual transmission.
5. Weird Grinding, Humming, Or Growling Noises
A telltale sign of an issue in your car is weird sounds coming from it that were not there before. Unnatural sounds can be irksome, and they do usually indicate a bigger problem cooking under the hood. If you hear a growling, humming, or grinding sound that changes with the speed of your vehicle, it might be coming from the TCCM.
The reason behind this may be a mechanical fault, such as bad bearing causing sounds, a loose chain, or damaged gears, or a low fluid level.
A loose chain on a transfer case control module can rub a hole at the top of the housing. This is why there are rebuild kits you can buy. They come with new front half and chain. Changing the front case half and chain should, however, be performed by a licensed mechanic rather than a DIY-enthusiast.
6. 4WD Warning Light Illuminates
On some vehicles, there is a “service-four-wheel-drive” message that lights up on the dashboard whenever the system is not functioning optimally. Other vehicles will just keep the 4WD light on till the problem has been fixed. Needless to say, the issue can be a bad transfer case control module.
7. Four-Wheel Drive (4WD) Service Message
This message may pop up on the DIC, or Driver Information Center from time to time. Service or maintenance messages normally go away after the engine has been restarted after turning it off once. However, the message can be indicative of a bad TCCM and/or encoder motor or button pack.
8. Engine Hesitates After Ignition
Several things can cause hesitation in an engine, and a bad TCCM is one of them. If you’re driving and the engine is stuttering too much, it could be a sign of a problem in the transfer case control module. This might happen as a result of a wrong signal sent to the transmission by the TCCM. You have to change the TCCM to fix this issue.
Possible Causes Of A Bad Transfer Case Control Module
Typically, a transfer case control module will fail due to a leak somewhere, lack of regular maintenance, or regular wear and tear. We highly suggest addressing the fluid leaks as soon as they occur to prevent internal TCCM damage. Replacing the fluid of the transfer case regularly is extremely important. Check the owner’s manual for the service interval specific to your car’s transfer case.
Understand the symptoms of transmission failure because they do tend to mimic transfer cases. As a vehicle owner, you can get confused pretty quickly. Don’t jump to conclusions and try to fix a problem that isn’t even there.
What’s The Problem: Bad Transfer Case Control Module Or Bad Transmission?
The transfer case control module is a part of a vehicle’s drivetrain and they both have separate functions. Despite this, the signs of a transmission failure mirror those of a faulty transfer case control module. This can confuse vehicle owners who are trying to repair their cars themselves. On that note, do not tamper with any of the components of your vehicle if you do not have adequate knowledge about it.
To avoid any confusion, get a professional to do a proper diagnosis of your vehicle if you suspect a transfer case issue. Not only do they have the proper tools and years of experience to back it up, but they will also be able to assess the condition of your vehicle more efficiently.
Keep in mind that bad 4WD locking hubs can be considered a part of transfer case problems. If they cannot engage, they damage the front differential too. Side note: A few older transfer case systems, like early 90s Fords, will cause the Powertrain Control Module (PCM) to use another shift schedule when the “Low Range” indicator is illuminated. As a result, the vehicle shifts through all gears at low speeds.
Interestingly enough, something as simple as a bad fuse can cause this problem.
Can A Bad Transfer Case Control Module Damage The Transmission?
There have been instances where catastrophic transfer case failures can harm other components of your vehicle, like the transmission. It is a good idea to check any known problems within your car as soon as they pop up to avoid the problems from piling up and doing more damage.
A few Ford trucks were experiencing difficulties with their electronic modules. It would put the vehicle in 4WD at highway speed randomly, causing unprecedented destruction. There is a dealer program about this issue, so get your VIN checked at your local Ford dealership to understand if your car is at risk.
What To Do When Transfer Case Control Module Goes Bad
If you see any of the symptoms mentioned above, you must have the transfer case control module checked immediately. A simple diagnostic test for a vehicle generally runs anywhere between $85 to $120. However, some mechanics report that even the diagnostics cost can climb up to $400.
We suggest checking in with your mechanic first to know what to expect. Not all auto shops charge for a diagnostic if you promise to let them perform the repair work if any issues are suspected.
After the initial diagnostics, a suspected case of transfer case control module will call for the TCCM to be removed, disassembled, and checked for signs of mechanical or physical damage. The service technician will decide if it is possible to fix the assembly or if you have to change it altogether. When having a module checked, the first thing anyone should do is to perform an in-depth code scan of it.
There are tons of parts with motors and sensors in the transfer case control module, so performing a code scan can help you understand what is up with the system for a cheap and quick repair. If you can, repair the module instead of replacing it as the latter is rather pricey.
It is a big part of any vehicle, especially if you need to switch between 4WD and 2WD, so having a functioning one is quite important.
How To Test Transfer Case Shift Motor?
The transfer case shift motor is the most common culprit behind any issues with the transfer case control module. This guide can be applied to any vehicle model and make TCCM testing. To start the test, however, you need a handful of common mechanic tools, like jack stands and jacks as well as a test light.
Remove the transfer case shift motor. Raise the vehicle from ground level and support it using jack stands. Slip under and find the transfer case motor. It resembles a window motor in appearance and sits on the back of the case. There are generally three to four bolts securing it in place.
Take out the bolts and unplug the linked connectors. Remove the motor and place it next to you safely to continue with the rest of the test.
Use a test light to test the transfer case motor. Locate the orange and yellow wire on the actuator as that is what controls the motor. These 2 wires are connected to the motor itself. Adjust the Ohm to 200 and place the probes on the yellow and orange wires.
The reading should be between 2.2 to 2.7. Anything over this range can be considered abnormal and lets you know that you have a bad shift motor.
Check the transfer case motor using a battery pack. An alternative way to check the transfer case motor is by using a portable jumper pack or a car battery. Take the multimeter leads and link them to the jumper pack terminals. Ensure the probes aren’t crossing each other. The point of this test is to get the gear to move around. This is why the probes must be connected to the yellow and orange wires.
The transfer case motor gear must move in both directions freely. If it is the other way around, you need to replace the lousy shift motor situation going on. A transfer case shift motor goes for around $50 to $80.
If you can locate the source of the problem and repair it, you will be lucky enough to get away without dealing with the hassle and price of replacing the TCCM altogether. However, if the TCCM fails or sustains mechanical damage, your only option may be to replace it. Changing a transfer case typically costs between $2,500 to $2,750.
It can be less expensive on some vehicles, rounding up to $2,300, while other jobs will be more complicated and run for $2,900 at the very least. Thus, the cost varies vastly based on the details of your problem.
Labor Costs For Replacing A Transfer Case
Labor costs associated with replacing a transfer case can be rather high as this is a lengthy fix. The average labor costs range between $435 – $650. To get a better idea of the labor costs, to have to understand everything that is involved with a repair.
First things first; the oil has to be drained from the TCCM so the driveshafts can be removed. After that, the TCCM has to be disconnected from the drivetrain as well as all the other electronic components. A transmission jack is used to support the transfer case so the mounting bolts can be safely extracted. Once the TCCM has been removed, it will be disassembled, checked, and cleaned.
If the mechanic discovers any leaks or damage, they will determine if it is possible to repair the part. If not, you have to pay to get a new part installed. Moreover, the various gaskets and seals have to be changed and the driveshaft cleaned before they can reassemble the parts and refill the transfer case.
Parts Cost For Replacing A Transfer Case
The main expense in replacing a transfer case comes from the new transfer case itself. A rough estimate of these parts is about $1,700 to $2,400, determined by the make and model of your vehicle.
Some owners want to save some money by buying a used part. Although this can save you a few coins, the purchase is risky. Only do this if you get some sort of warranty with the part or on the work. You can surely still go on a hunt for quality secondhand pieces.
So if you see any of the signs given above, test and repair the transfer case motor before the problems exacerbate. The problems can be quite severe, like damage to the transmission. This is why one should have an idea about the transfer case control module when owning a vehicle.
However, your primary response to noticing two or more symptoms mentioned above should be to run an in-depth diagnosis on the car with a high-end scan tool. The TCCM contains many system components with sensors and actuators. Running a scan beforehand will save you money.
1. Can I Drive With A Bad Transfer Case?
Technically, you can, but we do not recommend it. Driving with a faulty transfer case control module can cause a slew of problems. One of the most significant issues is a fluid leak. A seal exists between the transmission and the TCCM which, if damaged, can cause internal or external transmission fluid leaks. If this happens, the transmission fluid may leak out and cause bigger problems to the transmission.
A faulty encoder motor is another reason you should never drive a car with a malfunctioning transfer case control module. When it fails, it will register a C0327 error code in the computer, causing the engine to stutter.
2. How To Reset Transfer Case Control Module?
To reset and clear the transfer case control module, pull the five amp TCCM thread bridge at the bottom of the fuse box. Wait for at least 30 minutes and then replace the fuse. Next, turn the electric key and wait for the flashing of the 4×4 light. Turn your engine off after that. You have to repeat these steps five times before restarting your car.
3. What Happens When A Transfer Case Motor Goes Bad?
Your car might permanently be left in a neutral state if the TCCM fails during operation. In addition, if the transfer case control module fails electronically, the usual high-to-low gear can shift from 2WD to 4WD.
These tools have been tried and tested by our team, they are ideal for fixing your car at home.