Signs of a Bad Transmission Control Module & TCM Replacement Cost

October 28, 2019

Signs of a Bad Transmission Control Module

TCMs and Replacement Cost

Some of the most common signs of transmission control module failure include trouble shifting gears, getting stuck in gear, and lower gas mileage. But there are so many other red flags to look out for. Any signs of a bad transmission control module warrant a trip to your local mechanic. Your vehicle’s transmission control module (TCM) is like a tiny computer. It has the important job of interpreting electrical sensor output of components in an engine with an automatic transmission.

What is a Transmission Control Module?

The TCM transmission module processor helps understand various signals transmitted by the drivetrain’s engine control module (ECM), and outputs signals to control a vehicle’s speed, shifting, and regulate the temperature inside the transmission. The module’s input speed sensor sends critical rotational speed measurements to the TCM to determine the actual rotational speed of the torque converter.

The wheel speed sensor also works together with the TCM. Unlike having to manually engage the clutch with your left foot in a vehicle with a manual transmission, the wheel speed sensor tells the TCM when to decouple the transmission (aka engage the clutch). The wheel speed sensors also tell the module the speed of the car, whether the vehicle is going up or downhill so that it can adjust gear and tire rotation accordingly. If any of these sensors go bad, the results can spell disaster for your vehicle’s performance at best, and extremely dangerous at worst.

How to Find Out if It’s a Bad Transmission Control Module

If you experience any of the signs indicative of a blown transmission module, we highly recommend that you contact your local auto transmission shop. Symptoms of a bad transmission control module include:

You can’t shift gears or your vehicle is stuck in gear
You experience significantly lower gas mileage
Your vehicle seems to have trouble downshifting when your vehicle slows down
Your vehicle’s engine roars loudly and has difficulty shifting to higher gears when you attempt to accelerate
Your vehicle’s gears shift unexpectedly to another gear or neutral when you’re driving
It feels like gears ears slipping or catching when speeding up or slowing down
Your transmission is overheating quickly and you haven’t even driven very far
Your Check engine light on throwing p codes P0612, P0613, P0700, or P0706

Experiencing any of the warning signs of a bad TCM?

If you are unable to accelerate as fast as you should, or your gears are slipping, your car is unsafe to drive (even if it’s still semi-operable). Contact your local transmission mechanic to get it checked out immediately.

Can a Bad TCM Cause Transmission Problems?

A bad transmission control module can cause other transmission problems when it fails to mix the fuel/air ratio properly. This can affect your vehicle’s responsiveness immensely and cause it to jump or kick unexpectedly. When a driver cannot anticipate the acceleration or deceleration of the vehicle they are driving the situation is very dangerous and requires immediate attention by a licensed mechanic.

Is Your Car or Truck in Limp Mode?

When only one or two gears of a vehicle are working, it is said to be in “limp mode”. Limp mode is the vehicle’s safety default mode, and the automobile needs to have the TCM replaced for it to be driven again safely. If you’re experiencing any signs of a bad transmission control module, contact your local transmission place to get the problem diagnosed and fixed.

TCM Replacement Cost

The cost of TCM replacement depends on the make and model of your vehicle, plus the cost of parts and labor. It’s also important to factor in the amount of time it could take to replace the module because some imported parts can take 2 to 4 weeks to arrive.

TCM Swap & Labor

While swapping out a box might seem simple, the TCM is located inside the transmission in many modern cars, trucks, and SUVs. Opening the transmission is a laborious task, which is why it is reasonable to expect labor costs of at least $300 to replace the transmission control module.

In many older models (especially automatic transmissions) the module is located in an area of the engine that is much easier to reach. Replacing it in some of these older models simply means pulling a part out and plugging in the new or refurbished one. Unfortunately, it is not always that straightforward.

A licensed mechanic should do a thorough diagnostic and inspection of your vehicle to properly pinpoint the issue, don’t just rely on the diagnostic code reader. Often times, when the TCM is malfunctioning, it registers confusing codes that may not be accurate.

TCM Part Cost

The cost of the control module itself varies and as you might expect, replacing import TCMs is usually more expensive. These prices were found using an online search to serve as examples, and do not reflect the exact amount it will cost to replace or repair your control module.

Transmission Control Module Cost by Make and Model
Make	Model	Year	Cost
Honda	CR-V	2015	$360
GMC	Sierra Denali	2015	$260
Volvo	XC90	2013	$950
Volvo	S80	2010	$1240
Ford	Explorer	2012	$450
Chevrolet	Suburban	2014	$470
BMW	320i	2001	$50
Jeep	Cherokee	1996	$100
Toyota	Camry	2011	$180
Subaru	Outback	2009	$150
Ford	F150	2010	$440
Mercedes	CLA	2014	$350
Mercedes	Sprinter 3500 Diesel	2017	$370

Vehicle Makes & Models with Problematic or Recalled TCMs

Ford Focus. 2012 to 2016 Model Year Ford Focus TCM was recalled, and for a short time, Ford was offering to replace the TCM for free and update a software bug that blocked the driver from getting a TCM failure warning. The same TCM was also used in the 2011 to 2015 Ford Fiesta and was also included in a factory recall.

Dodge Dart. The 2013, 2014, and 2015 Dodge Dart TCM recalls were issued by the manufacturer because a faulty mounting bracket that could cause the car to shift into neutral unexpectedly while driving.

Jeep Cherokee. Jeep issued a factory recall for its 2014 Jeep Cherokee because of a supposed software issue that could also cause the vehicle to shift into neutral unexpectedly while it is in drive. The unexpected change in acceleration would be very dangerous for the driver and the surrounding vehicles.

Fiat Spider 124. The manufacturer issued a recall for the automatic 2017 to 2019 Fiat Spider 124 because of a software problem that could cause the car to decelerate or downshift suddenly without warning.

Mercedes-Benz 722.9 7G-Tronic TransmissionThe problematic 7G-Tronic transmission was used in the 2004 E-Class E350 and SLK-Class R171; the 2005 CLS550, R-Class W251, and M-Class W164; and the 2006 G-Class X164. This particular transmission model failed at such a high rate that they ran out of replacement parts and people had to look at 3rd party options. There are plenty of replacement parts available now, including the 7G Tronic conductor plate transmission control module. A few lawsuits were filed arguing that the transmission valve body was faulty before it was installed in the new vehicles. When the defective valve body conductor plate fails in the 7G Tronic transmission, the car can shift into limp mode suddenly, endangering the driver and others on the road.