A bad TCM on a Chevy can keep you pinned right where you are as the rest of your offroad buddies make quick work of the country roads ahead toward Mother Nature, and we know just how frustrating that can be.
With our expertise in dealing with TCMs on vehicles of all shapes and sizes, a simple reset may be all that you need to stick with the pack. But how do you exactly reset a Chevy TCM?
We’ll be diving into different TCM reset methods to get your Chevy back in gear and shifting right, so be sure to take notes!
How do you reset a Chevy transmission control module (TCM)?
A Chevy transmission control module can be reset by following the universal procedure of turning the ignition on, stepping on the gas pedal, and then turning the ignition off.
You can also try disconnecting the TCM or the battery to reset the TCM, though this may not work for some Chevy models.
Transmission control modules or “TCMs” work very similarly between any cars equipped with an automatic transmission, so even Chevy TCMs are able to be reset using universally known methods across different car brands.
For instance, resetting a Chevy TCM can also be done using the same method as you would in a Dodge (how to reset dodge transmission control module), which is by turning the ignition key on, stepping on the gas pedal, and turning the key off again.
Let’s not forget that TCMs are electronic devices powered by the vehicle’s battery, and certain Chevy vehicles can also have their TCMs reset by either disconnecting the TCM’s power cable or the battery cables themselves.
Once you are able to reset your Chevy TCM, all of the data or parameters regarding your shift patterns will go back to their default settings, enabling the TCM to “relearn” and adapt to your current driving.
What are the methods to reset a Chevy TCM?
The 1st method to reset a Chevy TCM is to remove the battery cables (negative first), though this may not apply to some models.
The 2nd Chevy TCM reset method is by unplugging the TCM’s power and data cable.
The 3rd method is to turn on the ignition, step on the gas pedal, then turn off the ignition.
1st Method (Disconnect Battery)
Disconnecting your car’s battery is a commonly known method for resetting a TCM, though the caveat to this is that it will not always work for every single vehicle model.
Chevy TCMs, in particular, don’t always get reset just by simply removing the battery cables, which means you would have to do some trial and error between all the methods we’ve listed here for your specific Chevy model.
Otherwise, if you choose to go this route, then make sure you remove the battery’s negative cable first before the positive one. Leave them disconnected for at least 30 minutes before reconnecting them again.
If the TCM doesn’t reset and your transmission still acts the same way, then you may have to use a scan tool to actually perform the reset or try the other two methods below.
2nd Method (Disconnect Transmission Control Module)
Another method that you can try to reset the TCM on a Chevy is disconnecting the module from its main cable, which serves as both its power cable and data cable.
However, before you actually unplug the TCM from this end, it’s also recommended to first disconnect the battery cables just like we’ve discussed above.
After you’ve disconnected the battery, you can then start to locate the TCM itself, which is commonly found at the back of the transmission case. This is how it specifically is for the older 4L60E TCM.
In some Chevy models, the TCM may be attached to the transmission valve body itself, like in the case of the 6L80E and 6L90E transmissions. You need to remove the oil pan to get to the valve body and TCM, so we recommend asking a mechanic for help.
Once you’ve gained access to the TCM, remove any bolts or clips holding the cable in before unplugging it carefully.
After a few minutes, you can then reconnect both the TCM and the battery to check if the reset has worked and the module is not causing any more issues with your transmission shifts.
3rd Method (Ignition and Gas Pedal Procedure)
The third method in resetting a Chevy TCM is one of the most universally known methods that works for other vehicle brands as well, which involves both the ignition and the gas pedal.
With that said, there are still a few details about this method that are specific to certain brands like Chevy, such as the pattern to which you turn the key in the ignition and how long you should step on the gas.
Thus, be sure to follow the steps below carefully so that you can successfully do a full reset on your Chevy’s TCM.
How to Reset Chevy TCM Using Ignition and Gas Pedal:
• Turn the ignition key to the “ON” position to turn on the dashboard electronics without starting the engine up.
• Push the gas pedal all the way to the floor for about 10 to 15 seconds.
• Turn the ignition key to the “OFF” position while still keeping the gas pedal pressed.
• Release the gas pedal slowly while carefully avoiding touching the other pedals.
• Wait for about 1 to 2 minutes without using or touching any electronics.
• Once the TCM has been reset, turn on the car and go for a test drive to give a chance for the TCM to relearn and adapt to your driving habits.
The reset procedure above is specifically for TCMs paired with GM/Chevy automatic transmissions, and not getting the steps down to a T may easily disrupt the resetting process and you will have to start over.
For instance, there is a reason why the gas pedal should be pressed all the way to the floor instead of just partially, as this activates the “kick-down” switch located underneath the gas pedal.
Under normal driving, the activation of the kick-down switch signals the TCM that the driver needs maximum performance from pressing the gas pedal all the way, which then results in the transmission shifting down or “kicking down” a gear.
Thus, the kick-down switch is also an important part of the TCM’s resetting and relearning process, especially under hard acceleration.
What is a transmission control module (TCM)?
A transmission control module (TCM) or transmission control unit (TCU) is an electronic device responsible for controlling automatic transmission systems.
The transmission control module uses sensors to monitor the speed, throttle, input, and other parameters to shift at the most optimum time.
Transmission control modules (TCM) have a lot in common with a vehicle’s main computer, the ECU (electronic control unit). However, the difference is that the TCM solely focuses on the operation of automatic transmissions.
Depending on the vehicle model and transmission, the TCM may be attached to the transmission valve body or located separately near the transmission case.
TCMs work hand-in-hand with many different sensors inside the engine and transmission, which feed them essential pieces of data or “parameters” to gauge when is the perfect time to perform a gearshift.
Through these sensors, the TCM is able to adjust to different driving situations. As an example, pushing hard on the gas pedal can trigger a downshift until the transmission upshifts again at a higher RPM.
In comparison, just lightly feathering the throttle as you’re just pulling out of a parking lot will only result in earlier shifts at lower RPMs, which also consumes less gas and leads to better fuel economy.
How does a transmission control module (TCM) work?
A transmission control module (TCM) determines the gearshift timing by the signals it receives from different engine and transmission sensors.
Once the TCM receives signals (input), it will send its own signals (output) to the transmission and tell which gear it should be in based on the situation.
We’ve talked about how transmission control modules or “TCMs” are programmed to operate on specific data or “parameters” provided by the sensors.
However, these parameters can actually be divided into two kinds. The “input parameters” are what the TCM receives from the sensors, while the “output parameters” are what the TCM sends to the transmission and other controllers.
Input Parameters and Sensors
The transmission control module (TCM) initially receives signals from different sensors, which become the “input parameters” that serve as the basis for the TCM in calculating the correct shift timing.
One good example of a sensor that feeds an important input parameter to the TCM is the vehicle speed sensor (VSS), which specifically provides data about the current speed of a vehicle.
Similarly, the throttle position sensor (TPS) is another essential source of input for the TCM. As its name suggests, the TPS provides data on the current position of the throttle or gas pedal, or in other words, the current amount of load on the engine.
This pairing between the vehicle speed sensor (VSS) and the throttle position sensor (TPS) is one of the most commonly used sources of input parameters for a TCM, though there are also other sensors that provide different parameters.
TCMs can also utilize data from the turbine speed sensor, transmission fluid temperature sensor, and even the cruise control module on vehicles with modern cruise control features.
Let’s also not forget about the kick-down switch underneath the gas pedal, which tells the TCM that the throttle has been fully pressed, making a downshift or “kick-down” in gears necessary given the situation.
Output Parameters
Once the transmission control module (TCM) has received signals or input parameters from the different kinds of sensors we’ve discussed above, it then sends its own signals or “output parameters” to the transmission, ECU, and other controllers.
There are several different transmission solenoids that receive instructions from the TCM via its signals, including the shift solenoid, torque converter clutch solenoid, and pressure control solenoid.
Again, depending on the initial signals received by the TCM, the transmission may be tasked to shift at a certain time that’s optimal for the current driving situation.
Aside from solenoids in the transmission, the TCM can also send signals or output parameters to different controllers outside of the transmission, such as the cruise control module and even the malfunction indicator light (MIL).
The TCM may command the cruise control module to deactivate if ever a neutral gear is engaged, or it may trigger the malfunction indicator light (MIL) to turn on if a transmission problem has been detected.
What are the symptoms of a bad transmission control module?
A bad TCM can cause symptoms like an illuminated warning light on the dash, delayed shifting, being stuck in neutral or 1st gear, and reduced fuel economy.
In addition, a bad TCM can also throw error codes such as P0613, P0700, and P0706 stored within the vehicle’s computer (ECU).
Illuminated Warning Light on Dashboard (With Error Codes)
One of the first symptoms that may pop up if there is something wrong with your TCM is a warning light being illuminated on your dashboard or gauge cluster.
Depending on the vehicle, a bad TCM may trigger a separate transmission warning light, which is usually displayed as a small gear icon with an exclamation mark, or a notification on your screen that says to check your transmission.
In other vehicles, a bad TCM may simply trigger the check engine light (CEL) or other similar malfunction indicator light (MIL).
Furthermore, if you ever get a warning light and you suspect that it may be due to a bad TCM, then one way to confirm this is by scanning your vehicle’s ECU if there are any error codes stored in it.
Warning lights are usually accompanied by error codes, and in the case of a bad TCM, you’re most likely going to be getting codes such as P0613, P0700, and P0706 when using a scan tool.
All three of these codes pertain to an issue with your TCM or transmission, so be sure to have the affected parts repaired or replaced right away.
Unable to Shift to Higher Gears
Whenever a transmission control module (TCM) is malfunctioning, you may notice that your transmission struggles to shift up to higher gears.
This means that the transmission may not be able to shift right away since the TCM fails to communicate with it, which means that your engine’s RPMs may continue to climb even at light throttle.
Slow or Delayed Shifting
Similar to the last point, one of the most common symptoms of a bad TCM is that there is a delay in shifting, which is especially more noticeable when you’re accelerating.
The transmission may take just a split second longer to shift into the next gear, and you may feel that the engine is freely revving at one point before engaging another gear.
Though, unlike the first symptom, slow or delayed shifting isn’t just limited to upshifts, as it can also happen during downshifts.
An automatic transmission typically downshifts whenever you step on the gas hard, but with a bad TCM causing shifting delays, it may take noticeably longer for it to “kick down” a gear and let the engine rise in the RPMs.
You can imagine that this would be quite annoying when you’re trying to overtake another vehicle, as a delayed downshift will also affect your car’s acceleration performance, not to mention it’s also a safety risk.
Stuck in Neutral or 1st Gear
If your car’s TCM is going bad, then there’s also a chance that you’re going to get stuck in either neutral or 1st gear and will be unable to shift to any other gear.
Getting stuck in neutral essentially means that the engine will only freely rev and you will not be going anywhere at all, while getting stuck in just 1st gear will limit your speed only up until you hit the limiter for that gear.
In other cases, you may get stuck in any of the other higher gears. While you may have a higher top speed, the engine will struggle to accelerate from a stop due to the stuck gear being too high and the RPMs being too low.
Reduced Fuel Economy
A bad TCM can also ultimately lead to reduced fuel economy because of all the other shifting issues that start popping out.
To give you an example, if a bad TCM delays shifting until the engine reaches a much higher RPM even at just partial throttle, then you would be putting extra unnecessary load on the engine that makes it consume more fuel.
A normal functioning TCM would tell the transmission to shift earlier if you’re just going for a leisurely cruise. This is basically how a TCM contributes to getting better fuel economy in a certain vehicle.
Where is the TCM located in a Chevy?
The TCM location on a Chevy can vary depending on the vehicle model, but it’s typically located at the back of the transmission case, like in the 4L60E transmission.
In other Chevy models, the TCM can also be commonly found next to the ECM/ECU at the passenger side of the engine bay.
4L60E TCM Location
The 4L60E TCM is located at the back of the transmission case and hidden under its own cover. It is also located under the vehicle’s engine control unit/module (ECM/ECU).
6L80E/6L90E TCM Location
The TCM for the 6L80E and 6L90E transmissions is located within the transmission itself. More specifically, it is attached to the transmission valve body.
You would have to remove the oil pan and filter to gain access to the 6L80E or 6L90E valve body and TCM.
8L90 TCM Location
The 8L90 TCM is typically located separately from the transmission and on the firewall at the back of the engine bay on Chevy truck models.
What are the causes of transmission control module (TCM) failure?
Causes of TCM failure can include physical damage to the TCM, voltage overload or surge, being exposed to too much heat or vibrations, and faults in the electrical wirings.
Physical Damage to TCM
Physical damage to just about any electronic component can cause it to malfunction and fail, and this is also the case for the transmission control module (TCM).
If a vehicle were to get into a front collision or anything that could knock the TCM out of place, then the TCM could potentially get damaged and possibly even fail then and there.
Voltage Overload/Surge to TCM
Most TCM failures have commonly been traced to a voltage overload or surge towards the TCM, which will damage its circuit board and cause the entire module to fail.
One instance where a voltage overload can happen is if a vehicle’s “soft starter” is unable to limit the amount of voltage supplied to the engine during initial startup.
The unregulated amount of voltage may cause movement within the transmission when starting the engine, which results in a surge of voltage to the many integrated circuits (ICs) inside the TCM and causes it to fail.
Exposure to Excess Heat or Vibrations
A TCM can also potentially go bad when it’s exposed to too much heat or vibrations inside the engine bay.
The excess heat may melt through the TCM’s circuit board, whereas too much vibrations are also no good for a TCM and any similar electronic hardware on a car.
Faulty Electrical Wiring
The TCM is part of an entire system of different wirings inside a car, and if one of those wirings were to suddenly become faulty, then it may cause a short circuit in the TCM and cause it to go bad.
Hence, it’s also worth checking your car’s electrical wirings when you’re having issues with your TCM and replacing them when necessary.
Will a bad TCM throw an error code?
A bad TCM commonly throws diagnostic trouble codes such as P0613, P0700, and P0706 that all point to either an issue with the TCM or the transmission itself.
Common Error Codes of a Bad Transmission Control Module (TCM):
• P0613 – A fault has been detected in the TCM’s internal control processor or circuitry.
• P0700 – A fault has been detected in the vehicle’s transmission control module (TCM).
• P0706 – An incorrect signal has been detected from the transmission range sensor (Transmission Range Sensor Circuit Range/Performance)
How do you reprogram a Chevy TCM?
A Chevy TCM automatically reprograms after a reset by relearning and adapting to your current driving inputs.
However, a new TCM needs to be reprogrammed by a mechanic or dealership using specialized software and equipment so that it properly adapts to your particular vehicle.
How much does it cost to reset/replace a TCM?
Resetting a TCM can be done for free if you were to do it yourself, as you only need to follow specific methods that don’t need any sort of equipment.
However, replacing a TCM can cost between $500 and $900 on average depending on the vehicle and whether or not you can do it yourself.
How much does it cost to replace a Chevy transmission?
Replacing an entire Chevy transmission system can cost upwards of $1,000, with brand-new transmission replacements costing a total of $2,000 to $5,000 depending on the exact Chevy model.
Frequently Asked Questions (FAQs)
