Symptoms of a Bad Transmission Control Module

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bad transmission control module

If you’re having trouble with your vehicle and it seems to be shifting roughly or hesitating then this could be a sign that there is an issue with the transmission control module (TCM). This blog will give you some information on what it is, how to tell if it needs replacement, what causes these malfunctions, and what you should do if yours does need replacement.

What is a transmission control module?

A transmission control module is an electronic device that collects data and processes signals in order to regulate gear shifting. It works closely with other parts such as the engine, brake pedal position sensor, transmission fluid temperature sensor, turbine speed sensor, and throttle position sensor. Without a transmission control module (TCM), your transmission would not be able to change gears effectively and consistently, which could ultimately damage other parts of your car.

Why is a transmission control module important?

A transmission control module is important because it controls your transmission’s shifting, something that constantly has to happen in order for the car to go. Without a transmission control module regulating this process, you could experience rough and inconsistent gear changes which can lead to other problems such as reduced fuel efficiency or loss of acceleration completely.

These parts are designed to improve the shift quality of your transmission system. This means that shifting between gears is a smoother, easier process that can help preserve gear durability and keep you on the road for longer! Furthermore, this part’s ability to send codes to your car’s computer helps identify any potential issues with transmissions before they become serious problems under the hood.

What are the signs of a bad transmission module?

If any of the following symptoms sound familiar, it’s likely that you’re experiencing a problem with your vehicle’s transmission control module. Transmission problems can lead to many issues for drivers; not being able to shift properly and causing accidents or injury is just one consequence. On top of that, driving with faulty wiring in the transmission could cause long-term damage if left untreated!

Check engine light is on

Having your check engine light on can mean a number of different things, however, the transmission control module will often trigger the check engine light in order to indicate that it has malfunctioned.

If you always have your transmission serviced when this light is on, then there may not be any transmission problems. If you start noticing issues when you change gears and your check engine light is on, then there is most likely an issue with your TCM or some other part of your transmission.

Irregular shifting

Automatic transmissions rely on the TCM to control the shifting, a faulty transmission control module can cause irregular shifting. This can be potentially dangerous and could lead to an accident. For example, if your vehicle shifts into another gear without warning, then your transmission control module definitely needs to be replaced. You should not continue driving as shifting into neutral on the highway could be disastrous.

Difficulty downshifting

Your transmission should gradually be going into lower gears as your speed decreases. At a stop, an automatic transmission should ideally be in first gear so it’s ready to go when you need to start moving again. Sometimes transmission control modules can malfunction and cause a transmission to downshift too quickly or not at all.

If your car isn’t shifting properly and seems like it’s stuck on the wrong gear, then it’s likely an issue with your TCM.

Difficulty shifting into high gear

When your car’s transmission doesn’t engage the higher gears, it can cause some serious problems. Remember that each gear has a maximum speed and you may never reach this speed if the TCM refuses to shift into a new gear.

When your engine is revving up without shifting from one gear to another, you probably have an issue with your Transmission Control Module (TCM). This faulty TCM will prevent you from reaching top speeds in any given class of vehicle.

Stuck in neutral

If your transmission is stuck in neutral, then you likely have an issue with the transmission control module. The transmission won’t shift and you’ll either be stuck in neutral or first gear.

Delay when shifting gears

The speed of your vehicle relies on cycling to various gears at the appropriate timing. If you have a bad transmission control module, then it will cycle to the next gear too slowly and this could impact how quickly you accelerate.

Poor fuel economy

When your transmission has an issue, then you can expect to see some changes in fuel economy.

An automatic transmission is specifically designed for optimal gear selection and timing with the goal of providing you with a good driving experience that will also help save money on gas.

If there’s a problem within this system such as when the TCM goes bad and affects, it means your engine may be working harder than usual! This causes more gas consumption which leads to spending more at the pump – so make sure those checkups are up to date!

Can you drive with a bad transmission control module?

It is not recommended to drive long distances with a bad transmission control module. Without a properly working transmission control module, you could experience serious mechanical issues that require expensive repairs. Cars without a working transmission control module are in danger of being unable to drive, being disabled, or only able to change gears at one or two speeds. Without the proper function of this device, your car may exhibit serious mechanical issues that could lead to expensive repairs.

How much does a new transmission control module cost?

The cost of a transmission control module replacement can be anywhere from $500 to $900 depending on the car and shop you go with. You’ll spend around $450 for parts, but labor will typically run between $50 – $200 dollars at most garages.

Repairing your TCM will in almost all cases be lower than replacing with a new module. On average, expect to pay around $300 for TCM repairs. While most TCM repair businesses will offer a warranty of some sort, it does pose a bit more risk if the repair is not done right. Also, you may need to ship your bad TCM to out-of-province or state so if you can’t afford not having your vehicle for two days while waiting on repairs, replacement would be a better option.


Transmission Control Modules (TCM) are a critical component of your transmission system. They monitor and control the transmission, providing accurate gear selection that can help you get better fuel economy as well as maintain reliable performance at high speeds. When TCMs malfunction or wear out, they can cause transmission issues like jerkiness when accelerating, hesitation while shifting gears, problems downshifting and trouble with changing to higher gears. If you’re experiencing transmission control module problems it’s time to take your car in to an auto repair shop.

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