www.gretchenbleiler.com is a participant of Amazon Affiliate program, we may earn a small commission from qualifying purchases made through our recommended links. Learn more

05 Signs of a Bad Transmission Control Module

The upgrade to the vehicle transmission control modules means that vehicles have better performance, better fuel economy, decreased emission, and a more reliable gear shift than the hydromechanical modules.

In addition, the transmission control module is programmed to send error codes to your car system in case of a malfunction with the transmission unit.

There may be damage to one or two sensors in the car or damage to the module itself, which may require a replacement.

Where this occurs, you would usually notice inefficiency in the gear system, including failure to change gear and other transmission issues.

What Is Transmission Control Module (TCM)?

The transmission control module is a type of engine control unit responsible for the automatic transmission in your vehicle.

The module functions with many sensors such as the vehicle speed sensor, wheel speed sensor, throttle position sensor and so on to help the vehicle when changing gear.

These sensors feed data to the module to help it calculate when to change gear.

In short, the transmission control module functions as a timer for the gear shift.

Before TCM, many vehicles used hydromechanical controls.

This essentially meant that the human functioned as the timer to decide when to change the vehicle’s gear.

See also  08 Tips On How to Get Better Gas Mileage in a Chevy Silverado : 2022

What Are the Signs of a Bad Transmission Control Module?

When you suspect that your vehicle has a bad transmission control module, there are 05 signs to look for.

The following are signs of a bad transmission control module:

01. Check Engine Warning Light

The Check engine warning light does not always mean that your transmission control modules are faulty.

With a couple of other signs like difficulty in changing gear and transmission issues, this could be a sign that your transmission control module is faulty.

The check engine light in your Chevy Silverado will appear on the screen of your vehicle dashboard.

You can use an OBD II scan tool to check for a trouble code or error to determine if it’s an issue with the transmission control module.

It would be best if you looked for the error code P0700.

You should know that your transmission module is bad where this occurs.

02. Stuck on the Same Gear

This can be very problematic for drivers and result in a bad driver experience and fuel efficiency.

You will experience here that you are either stuck in neutral or cannot move past first gear.

When you experience this, you have a problem with your transmission control module.

03. Problematic and Delayed Gear Shift

When your Chevy Silverado experiences a problematic or delayed gear shift, then this is a sign that your transmission control module is faulty.

In this stage, you would experience difficulties shifting to the next gear or a delayed response in shifting to the next gear.

Also, accelerating as your vehicle relies a lot on the gear shift will be difficult.

See also  How To Adjust Torsion Bars Chevy Silverado (DIY Method : 2022)

This makes it difficult to downshift to generate more torque for acceleration.

04. Difficulty with Downshifting

The process of downshifting is crucial in driving and acceleration.

Downshifting is when the automatic transmission shifts to a lower gear, which increases the torque and gives you more room for acceleration and better control of the vehicle during acceleration.

To better explain downshifting, where you are accelerating on a highway and then decide to slow down, the gear usually decreases until you reach a final stop, in which case your vehicle would be at first gear.

If you experience an issue with downshifting, your vehicle’s transmission control module is faulty.

05. Difficulty with Shifting Into a Higher Gear

When accelerating, your vehicle is also programmed to increase its gear gradually.

A bad transmission control module in a Chevy Silverado may not be the case.

This impact is that your Chevy Silverado will never attain a certain speed as each gear has a maximum speed it can reach.

Why is TCM Important for a Vehicle?

The TCM acts like a processor with memory and circuits to collect data and give data to other systems in your vehicle.

The TCM collects data from the vehicle speed sensor, wheel speed sensor, turbine speed sensor, transmission fluid temperature sensor and son, and feeds the engine control units and other systems to facilitate gear change.

Firstly, the transmission control module is solely responsible for gear change, without which your vehicle will fail to change its gear and will not perform properly.

Sometimes a faulty or bad transmission could mean the vehicle is stuck at neutral, which could cause serious friction and damage the vehicle system.

See also  How To Remove Transfer Case From 4L60E Transmission in 06 Steps

In addition, as earlier emphasized, the TCM works with other sensors to ensure optimal performance like fuel efficiency, decreased emission, etc.

Where there is no TCM, or it is faulty, the vehicle may be stuck in a particular gear for a long, which may cause the car to consume more fuel.

Finally, TCM gives the driver a great driver experience.

Since the driver is no longer focused on manually changing the transmission (which is now done by the TCM), they can focus on other aspects of driving.


If you notice any of the symptoms above.

Replace the TCM as soon as possible, or the problem will become worse.

Leave a Comment