Transmission Control Module Symptoms (9 Things to Be Aware Of)

Whether you’re a car enthusiast or just use your car to get from Point A to Point B, you should know that the transmission system is one of the most important parts of your car.

However, the transmission of your car is controlled by the transmission control module and can severely affect your car if it fails. Here’s what we found!

Transmission Control Module Symptoms

1. Check Engine Light On The Dashboard

If you see a light in the shape of an engine appear on your dashboard, it may be a sign of a faulty transmission control module.

On its own, the check engine light may indicate something innocuous like a loose fuel cap or wire.

However, if the check engine light comes on and you suddenly experience trouble with the gearshift, it’s highly likely to be a problem with your transmission control module.

As such, it’s essential to get your transmission system checked immediately.

2. Acceleration Lag

Aside from my point above, a faulty transmission control module may be to blame for a delay in acceleration.

Generally, the transmission control module responds when you switch gears to accelerate, which allows your car to move faster.

However, when the transmission fails to respond immediately, you may experience a brief delay before your car can move faster.

In this case, it’s crucial to bring your car in for repair right away.

3. Not Up-Shifting During Acceleration

Aside from lagging acceleration, failure to upshift may also be a symptom of a malfunctioning transmission control module.

Generally, your transmission should properly and timely change to higher speeds as you gradually raise your speed.

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However, when this doesn’t happen, your engine’s RPM will keep rising rather than slightly decreasing, after which an upshift occurs.

Thus, if the malfunctioning transmission control module won’t change to a higher gear, you might never reach the specified speed because each gear has a maximum speed it can handle.

4. Not Down-Shifting

Like the above, downshifting may also be a symptom of a failing transmission control module.

Generally, an automatic gearbox should be in first gear when at a standstill, so it is ready to go when you need to resume motion.

However, if the transmission control module is malfunctioning, you can still be in high gear while you slow down.

Thus, you’re in a gear that prevents you from properly accelerating when you need to start moving again, which may even prevent you from moving entirely.

5. Stuck In One Gear

Stuck In One Gear

Aside from the points above, if you’re unable to change gear at any point, it may be because your transmission control module is faulty.

In this instance, your car may stay in neutral gear or park despite you trying to switch gears to reverse or even drive.

Additionally, you’ll notice it if your automobile engages first gear and moves forward but won’t engage the following gear.

Therefore, this may be a sign of a bad transmission control module.

6. Erratic Gear Shifting

Moreover, erratic gear shifting may also indicate a malfunctioning transmission control module.

Generally, an automated transmission system depends on the transmission control module to perform the shifting.

Therefore, your transmission control module will probably need to be changed if your automobile suddenly changes into any gear that it wouldn’t ordinarily shift to.

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As such, you will need to have your automobile towed to a repair facility, so the module may be changed unless your car has a manual override option.

7. Transmission Slipping

One of the more severe symptoms of a bad transmission control module is transmission slipping.

Typically, your car moves faster when you accelerate, which is an indication that the power from the engine gets to your wheels, thus enabling your car to move faster.

However, in the case of transmission slipping, you may notice that you reach a higher RPM, but your car’s speed has stayed the same.

In this case, it may be because of a problem with the transmission control module.

8. Your Car Stalls When Changing Gears

Additionally, stalling when changing gears can be a sign of a faulty transmission control module.

As I mentioned earlier, timing plays a significant role in determining when you shift gears while driving.

However, if the transmission control module causes your gear to upshift too early, this may be causing your engine to stall or nearly stall.

Therefore, you could lose control of your car in this dangerous condition on the road, so you should get it fixed right away!

9. Poor Fuel Economy

In addition to my points above, poor fuel efficiency is typically a sign that your transmission system is having issues.

Generally, an automatic transmission is built with the finest gear selection and timing to provide you with the best potential fuel economy.

However, if your transmission control module is malfunctioning, this has an impact on timing, and your engine will have to work harder than usual.

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This implies that it will use more petrol than usual, costing you extra next time at the pump.

To know more, you can also read our posts on weak ignition coil symptoms, water in fuel filter symptoms, and transmission control module symptoms.


If you suspect you have a faulty transmission control module, it could be worth checking if you’re encountering issues with changing gears while driving.

Also, the check engine light on your dashboard could also be a symptom of a faulty transmission control module.

As such, you should bring your car in for repair and have the module fixed right away.

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