Signs of a bad transmission control module and the cost of replacement

Automatic transmission systems are different from their manual counterparts. Automatic transmission systems are more advanced and rely on computerized systems for their operation. Automatic transmission systems use a transmission control module (TCM) to select gears, optimize performance and control fuel efficiency. Driving around with a bad transmission control module is risky in many ways. Drivers must identify early signs of failure or defects affecting the performance of transmission control modules for timely repair or replacement before the car is grounded.

What is a Transmission Control Module?


A Transmission Control Module (TCM) is an electronic device that controls the automatic transmission in a vehicle. The TCM monitors the engine speed and the vehicle speed and uses this information to determine when to shift gears. The TCM also monitors the temperature of the transmission fluid and will make adjustments to the shifting pattern if necessary. In some cases, the TCM may also be responsible for controlling features such as cruise control and traction control.

The Transmission Control Module is an important part of a vehicle's transmission system, and it is important to make sure that it is functioning properly. If you suspect that your TCM may be having problems, it is important to have it checked by a qualified technician as soon as possible.

Signs of a bad transmission control module (TCM)

If your car starts having problems with the transmission, you'll feel it almost immediately. The ride won't be as smooth as it was, and you'll feel like the car is having a hard time accelerating every time. However, you should not rely only on your feelings and conjectures - below we listed the signs of a bad transmission control module, and if you notice any of them - contact a mechanic for professional diagnostics

Check engine light comes on


The use of advanced sensors allows drivers to monitor their vehicles in real-time. Several defects can cause the check engine light to come on. However, if the light comes on and the driver experiences difficulty when shifting, there is an issue with the transmission control module. A scan is necessary for the driver to pinpoint the source of the error. If the scan tool returns the P0700 code, you should have the TCM checked.

Bad shifting


A faulty TCM misinterprets computer signals. The car shifts into the wrong gears. In some instances, the gears change without human intervention and warning. Bad shifting is a safety risk. Once you experience this, take the car for repair.

Difficulty shifting to higher gears


The TCM controls the timing for shifting to higher gears. When the TCM is bad, engine RPM increases instead of dropping. In extreme situations, the transmission fails to change to high gear.

Problematic downshifting


When decelerating, the TCM should automatically downshift the gears. When the foot is released from the gas pedal, the transmission moves to a lower gear to optimize fuel efficiency. If the transmission control module is faulty, it becomes hard for the vehicle to downshift. 

The transmission is stuck in a single gear


A bad TCM causes the vehicle to get stuck in one engine. It is common for transmission to get stuck in a low gear (first gear) or neutral. The driver moves around at a limited speed or can’t drive the vehicle from rest.

Delayed shifting


The transmission control module controls the intervals at which the gears shift. The time for shifting from lower to higher gears and vice versa remains constant. However, if the TCM is damaged, there will be delays when changing the gears.

Low fuel economy


The TCM is essential for timing gear changes and optimizing fuel efficiency, depending on the driving speed. A faulty TCM causes a mismatch between the gear ratios and fuel consumption. Poor fuel economy can indicate that the transmission control module is bad.

If you are having trouble with your transmission, the first step is to check the TCM for codes. These codes can tell you what is wrong with your transmission and help you troubleshoot the problem. If you don't have a code reader, you can take your car to a mechanic or dealership and they can read the codes for you. Once you have the codes, you can use them to look up what they mean and start troubleshooting your transmission issue.

What causes transmission control system malfunction?

Some common causes include electrical problems, dirty or low fluid levels, and mechanical wear. Many times, transmission control system malfunctions can be caused by a simple problem that is easily fixed. However, in other cases, the cause of the problem may be more serious and require a more complex repair.

Can you drive with a bad transmission control module?

The answer is technical, yes, but it is highly not recommended. A bad transmission control module can cause all sorts of problems with your car's transmission, and driving with one can ultimately lead to further damage or even total transmission failure. If you're experiencing any issues with your car's transmission, it's best to have it checked out by a qualified mechanic as soon as possible. Trying to drive with a bad transmission control module is simply not worth the risk.

Cost of replacing the bad transmission control module

The average cost for a Transmission Control Module (TCM) Replacement is between $917 and $1,011. Labor costs are estimated between $70 and $89 while parts are priced between $847 and $922. This range does not include taxes and fees and does not factor in your unique location. Related repairs may also be needed.

Cost of repairing the bad transmission control module

is quite expensive. You're looking at a minimum of $200 just for the part, and that's not including labor costs. If your car is older, it may be worth considering a replacement transmission control module instead of repairing the existing one. A new transmission control module can cost as little as $50, which is a significant saving over repair costs.

When it comes to deciding whether to repair or replace your transmission control module, there are a few factors to consider. First, the age of your car. If your car is relatively new, it may make more sense to repair the existing module than to replace it. The second is the severity of the damage. If the damage is significant, it may be more cost-effective to replace the module rather than trying to repair it. Finally, your personal preference. If you're comfortable with repairing the module yourself, then that may be the route you want to take. Otherwise, replacing the module may be the best option.


A bad transmission control module causes multiple problems that affect engine performance and driving quality. Transmission-related failures are a safety risk. When drivers identify signs of TCM failure, they should visit a repair shop for further troubleshooting and immediate replacement of the damaged transmission control modules.