Here Is Why You Can’t Ignore The Signs Of A Bad TCM In Your Mercedes
Posted on April 2, 2021 by smikyautomowp
The TCM, or the Transmission Control Module, is one of the critical components of your Mercedes and works along with the automatic transmission system. Most modern cars will work with the TCM rather than a mechanical control or a hydraulic control system. For the most part, the TCM is set up to last a long time and it is not common for this component to need replacement. However, when the TCM breaks or wears out, then a replacement or repair is necessary immediately.
This module is a type of computer responsible for communicating information to the other computer systems in the vehicle. If it is not working, the rest of the computer systems will not receive important data and can’t operate your vehicle the way Mercedes intended. As soon as you notice signs or symptoms that the TCM is failing, you need to visit one of our qualified mechanics to fix the problem as soon as possible.
Common Warning Signs that Your TCM is Failing
The TCM does not go bad often, but when it does, the car owner needs to get it fixed as soon as possible. A bad TCM will spell a lot of trouble for the vehicle and how well you can drive it. Some of the most recognizable symptoms to watch include:
- The Check Engine Light: When you see the check engine light on your dashboard, there are a few potential problems that could make this happen. However, if the light turns on and you notice that there are some troubles with shifting in your Mercedes, then it is likely the TCM or another part of the transmission system is to blame. When you suspect this is happening, you need to take your car to one of our licensed mechanics to have the issue checked out. This will help you get the TCM or any other problem that caused the check engine light repaired before it becomes a bigger, more costly issue.
- Shifting Becomes Unpredictable: The automatic transmission system will rely on the TCM to control all of the shifting. This means that a bad transmission module can cause incorrect timing of shifts in some situations. Not only can this cause problems for your engine, as it won’t be in the proper gear and could cause high revolutions, but it can endanger you if you need to accelerate but cannot get up to speed.
Also, if your TCM is malfunctioning and shifts into neutral, you may need to replace the whole control module for your safety. You can’t even park safely when this occurs. Waiting to get this replaced and repaired can make driving really dangerous. If this occurs, pull over to the side of the road and turn on your hazards. Call for a tow to get it repaired right away.
- Shifting Problems to Higher Gears: As mentioned above, your engine works to increase your speed on acceleration. You should be accustomed to the transmission correctly shifting into the next gear at the right time. But when this does not happen, the RPM of the engine will continue to increase, rather than slightly dropping as it should during the upshift. Because each gear has its own maximum speed, you may not be able to reach the speed you want if the TCM will not shift.
- Problems Downshifting: This is a similar problem to the problem discussed above, but it happens in reverse. If you need to slow down to avoid the cars decreasing their speed in front of you, but the transmission does not shift over to the lower gear, this can cause engine problems. If the TCM is bad, you may continue to drive in a higher gear, even as you come to a stop. When you need to move faster again, you are in the wrong gear for accelerating properly, which may make it impossible to move at all.

Our team at St. Matthews Import in Louisville, KY is here to help with all of your auto repair needs. Our Hubbards Lane is the number one location in the area for all your automotive service and repair needs. Contact us today to get your appointment scheduled. We look forward to earning your repeat business.