Car System

Symptoms Of Bad Transfer Case Control Module

Mike Cross
Updated Oct 29, 2021
Symptoms Of Bad Transfer Case Control Module

Most cars are either front wheel or rear wheel drive, but some larger vehicles such as SUVs and Trucks are a four-wheel drive or can switch between two and four-wheel drive.

The switching between what style of driving your vehicle is is controlled by the transfer case control module. Sometimes this module stops working properly though, and this will prevent you from switching between two and four-wheel drive.

In this article, we will look at some symptoms of a bad transfer case control module and will also give you some suggestions on what to do about it.


Symptoms Of Bad Transfer Case Control Module
Symptoms Of Bad Transfer Case Control Module

How does the transfer case control module work?

Before going into detail on symptoms of a failing module though, we will first explain briefly on how the transfer case control module works.

By understanding how it works, you can better understand what things to look out for with your transfer case control module while driving so you can notice the symptoms of it failing sooner.

The purpose of the transfer case control module is to help your vehicle switch between to wheel drive and four-wheel drive.

The way it does this is it uses speed sensors to judge the speed of the car, and then it processes that information to see if a shift is safe and possible.

If you are going slow enough when you press the button to engage four-wheel drive, then the module will engage and allow the vehicle to switch into four-wheel drive.

The same is true if you are trying to turn four wheels drive off. It looks at your speed, and if you are going slow enough, it will shift the vehicle back to two-wheel drive.

This is a really basic explanation of what the transfer case control module does, but the key thing to know is it is responsible for changing the vehicle between two and four-wheel drive and thus has moving parts in it.

Symptoms of Failing Transfer Case Control Module

Since the transfer case control module has moving parts in it, the first symptom we will point out is grinding sounds.

When you press the button to engage or disengage the four-wheel drive if you hear grinding sounds after when the module changes the mode your vehicle is in, then that I am a problem.

Even if it works, it still means that there is something in the module that shouldn’t be. This could be a broken gear, debris from driving, or anything else.

If you have a grinding sound or clanking sound when the module is working, then you need to get it checked out right away, so it won't break completely on you.

The next thing tied into this is difficulty shifting gears. The difficulty could be audible, or you might just feel it in your vehicle when the gears are changing.

If the module has a challenge shifting the gears, then it might mean that they are damaged and this ties into the first one with the sound.

However, another reason why it might be hard for

transfer case system
Transfer case system

the transfer case control module to change gears is that it might not have enough fluid in it to lubricate it.

This could be from a leak somewhere in the system, so difficulty shifting is another sign to pay attention to and should be checked out farther if you notice it because shifting without the proper amount of lubrication will cause damage to the whole module.

The third symptom of a failing module is a vehicle that jumps in and out of four-wheel drive. This means that it might be in four-wheel and then switch to two wheels on its own or when you hit a bump.

Some might call this slipping out of gear. If the vehicle changes from four-wheel to two wheels on its own, then there is defiantly some damage to the parts inside the module, and the module needs to be checked.

This changing can be dangerous because it can lock up the wheels and cause you to wreck. This issue can also be caused if you have too much lubrication in the module from a leaking fluid line. This means that too much fluid is bad, but also not enough is bad too. Any issues liked this need checked out.

The last symptom of a transfer case control module that is having issues is one that won’t shift when it should or only shifts sometimes. This is generally caused by a speed sensor that has gone bad or isn’t working right.

If the speed sensor isn’t giving a reading or it thinks you are driving faster than you are, then it won’t allow the vehicle to shift from two-wheel to four-wheel drive or allow it to change the other way around.

What to do when Get Bad Transfer Case Control Module?

If you have any of these symptoms, then you should have your transfer case control module checked out. The first thing that you or a mechanic should do when having the module checked out is run an in-dep code scan on it.

The transfer case control module has a lot of parts with sensors and motors, so doing a code scan can help you figure out what is wrong so you can fix the module faster and hopefully cheaper.

You should try to have the module fixed if you can because replacing it can get really costly. It is an important part of your vehicle though, especially if you want to switch between two-wheel drive and four-wheel drive, so having a working one is important.


So, now you know what the transfer case control module does and some signs of one that is going bad. You know that trouble shifting between two and four-wheel means something is wrong and if you have noises coming from the module, then you really need to have it checked out.

You also know that if it slips out of four-wheel into two-wheel, then that is a sign of issues. The best thing to do if you notice any of the things mentioned is to have your codes scanned, so you can know the best way to fix your transfer case control module. Luckily though, you now know the symptoms of a bad transfer case control module so you can have it taken care of as soon as possible.

Mike Cross
Life is too short to drive with stock audio

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