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10 Bad Transmission Control Module Symptoms & Replacement Cost


All modern vehicles use a transmission control module, with the exception of manual transmissions. Bad transmission control module symptoms include slow or erratic changing gears and failure to change gears.

The transmission control module or TCM can be found in various places, depending on the model and make of the vehicle. These locations can include the transmission, inside the transmission, near the engine control module.

A failed transmission module can make your vehicle dangerous to drive for you and other drivers. Continue to read to learn what are the the signs of a bad transmission control module.

What is TCM (transmission control module)?

The TCM is a computer that controls automatic transmission systems and determines which gear should be used based on input from the engines computer or engine control modules, the throttle position sensor, engine RPM, speed sensor, acceleration, etc.

10 Most common signs of a bad transmission control module symptoms

TCM location on a ford transmission control moduleThere are a number of signs that the TCM is failing. If you detect any of these, it is best to have it checked by a professional before there is damage to your transmission. Repairing or replacing the transmission can be very expensive.

1. Transmission overheating

Transmissions can overheat for a number of reasons, including a defective TCM. Pulling heavy loads, heavy acceleration, the transmission stuck in a lower gear while accelerating to higher speeds.

Once a transmission overheats, the components and the transmission oil are less efficient, which may cause further problems. Have the TCM checked by a qualified transmission technician as well as have the transmission oil changed.

2. Shift lock in the same gear

A sure sign that the TCM is malfunctioning is when the transmission is stuck in the same gear and will not shift up or down as engine speed changes. For example, if the transmission is stuck in high gear, you may not be able to accelerate from a standstill position due to the high torque required.

A transmission stuck in 1st gear will limit the maximum speed you can attain even with the engine revving at a high RPM. The transmission should downshift as the car decelerates.

3. Gear is stuck in neutral

Another example of a malfunctioning TCM is when the transmission is stuck in the neutral gear. Regardless of which position the gear shift is placed in, the car will not move since the transmission is stuck in the neutral position.

Your car is not driveable in this situation and must be repaired. Car owners will have to arrange for their vehicle to be transported to a garage for possible repairs to the transmission and TCM module replacement.

4. Cannot shift properly into higher gears

The TCM is responsible for shifting gears as your car gradually increases speed. Each gear has a top-end speed, and the transmission should shift to the next gear as this speed is reached.

When the shift does not occur, your engine continues to revolve at a high RPM, without the corresponding increase in ground speed. Your vehicle may never allow you to reach highways speeds under these conditions, which could be dangerous to yourself and other high-speed traffic.

5. Gear shift have problems downshifting

Bad transmission control module and symptomsThe TCM (Transmission Control Module) is also responsible for downshifting the transmission as the ground speed gradually declines. Once you come to a stop at a stop sign or stoplight, the TCM should have shifted the transmission into 1st gear.

The transmission should be ready to accelerate. If the downshift does not take place, the transmission may still be in a higher hear, making it very difficult to accelerate from a stopped position. In some situations, the high gear position may prevent the car from moving at all from a stationary position.

6. Delayed shifting

Your cars TCM and transmission are designed to shift gears within specific parameters of engine RPM and ground speed. If the transmission shifts gears slowly, there is a loss of momentum, and the car can even slow down during gear changes.

If delayed shifting occurs while climbing a grade, the impact will be even worse. A bad TCM can cause the gears to change slowly and have a dramatic effect on the performance of the vehicle.

7. Poor fuel economy

The TCM, transmission and engine are designed to work in unison to deliver maximum power at maximum fuel efficiency. Any time the TCM is not performing properly, the fuel economy can be impacted.

For example, a transmission that shifts too late or not at all causes the engine to work harder at a less than an optimal degree. In most cases, more fuel is consumed, lowering the miles per gallon efficiency usually delivered by your car.

8. Check engine light

The check engine light can be illuminated for many reasons, and drivers should have their vehicles checked by a registered mechanic. Often there is a problem with the TCM module if the check engine light is on, and your transmission displays some of the above-mentioned symptoms.

A mechanic may use a scan tool to check the diagnostic trouble codes for an indication of what is causing the problem. A P0700 error code usually indicates a problem with the TCU (Transmission Control Unit).

9. Low transmission fluid

Low transmission fluid can cause erratic shifting. Symptoms include spikes in RPM levels during shifts, grinding noises, slipping in and out of gears, and erratic shifts. If you have these symptoms, the transmission fluid may be low.

Check for telltale signs of fluid leaks under your car. You may also notice the transmission overheating, such as a burning smell, since it must work harder with less fluid. Always pull over and avoid serious damage to the internal transmission components.

10. Transmission Gear slipping

As your transmission changes gears while accelerating, the transmission may fall back to the lower gear, which indicates gear or transmission slippage. Low transmission oil or a faulty transmission control module could be the cause.

Avoid driving the vehicle long distances and under heavy loads or up steep grades. With gears slipping, acceleration to highway speeds may not be possible, which could cause a dangerous situation on the highway with other higher-speed traffic. The transmission internal components could also be damaged.

Is it safe to drive your vehicle with a bad TCM?

Generally, it is not safe to drive your car with a bad TCM (Transmission Control Module). Acceleration, deceleration, erratic gear changes, and more make it difficult to navigate in traffic.

In addition, the risk is high for further damage to the transmission, which can drive up the cost of repairs significantly. Replaced transmission control modules can be expensive, and a damaged transmission is much more expensive.

How much is the (TCM) transmission control module replacement cost?

The cost of the TCM (Transmission Control Module) replacement can vary a great deal depending on the year, make, and model of the vehicle. The cost of parts and labor can range from $500 to over $1000 for many vehicles.

The TCM module is located in your car around the engine or near the transmission. Location affects the labor cost significantly. A damaged transmission can cost much more to repair than replacing the transmission module. Tech transmission repair service and parts are super expensive.

Is it possible to reset the failing (TCM) control module?

Location of TCM transmission control module diagramThe TCM (Transmission Control Module) may need resetting if it is not damaged. A damaged TCM must be replaced. Check online for detailed instructions regarding resetting the TCM for your make and model of vehicle.

It is definitely worth a try since you may be able to save a significant amount of your transmission repair costs. A faulty transmission or engine repair are the most significant repairs on a car.

Should I go to a collision center to check the TCM?

A failed transmission control module causes your transmission to change gears slowly, erratically, or not at all. Insufficient transmission fluid can also cause transmission overheating as well as slow gear changes and slippage. Avoid additional damage to your transmission.

Your transmission should be checked by a qualified mechanic? It is always better to use a mechanic because they can get the transmission module located fast without the need of repair manuals. Call a local repair shop if you are not able to shift your transmission gear.


Car owners may want to schedule transmission maintenance, and general car maintenance such as changing the engine oil, check the brakes for brake repair needs, check your battery for car battery replacement, tire repairs, safety recalls, and general car engine maintenance.

Poor car maintenance can cause warranty cancellation, affect your car worth and lease deals. Many people attempt to trade in a car with a defective transmission or sell 2nd hand cars with TCM problems. Buyers should beware.

If you own a heavy, super duty car like the Ford Escape or Dodge Ram, we recommend going to a collision center whenever you notice a transmission solenoid or TCM problem.

Also, rethink and evaluate your options if the repair that your vehicle needs are too expensive and your insurance claim submission does not approve the repair. Sometimes auto owners can be better of exchanging their cars.

Ask the dealer’s sales department for a car comparison of the current preowned inventory they have. They usually have a sell us your car type of deal for customers that are in your situation.

The finance application sometimes has plenty of special offers available like the military discount and the dealer discount. Contact us if you would like to join our team of writers. Now you know what are the the signs of a bad transmission control module symptoms and problems.

Last Updated on: January 26, 2023

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