Symptoms of a Bad TAC Module in Your Car and Ways to Fix It

The symptoms of a bad TAC module are a drop in gas mileage, slow reaction on pressing the gas pedal, bad idling, and also possible stalling when the engine tries to idle. Also, you may get a check engine light if the self-diagnosis system can register the code and catch the problem. This code will greatly help you locate and solve the problem.

TAC problems highlights

• Module's importance:High
• Prone to failure:No
• Reasons for failure:Sensor or actuator problems, water damage
• Ways to reset:Disconnecting battery
• Sphere of control:Throttle flap
• Symptoms of failing:Engine won't revup,only idling is possible
• Price to repair:Repair is complicated
• Price to replace:$350 - $800

What's the TAC module and how it works?

Basically, this is the more efficient and highly functional throttle sensor that controls the position of the throttle, sends the signals to change the position if needed, and sends the needed information to the PCM or ECU.

This module is extremely important for the optimal work of your engine. If it malfunctions, the throttle starts going crazy and basically doesn't know when it should open or close. This may lead to random RPM jumps, problems with acceleration, and all other problems that usually happen when the throttle body is broken.

The TAC module may be located in different places in various car models, but usually, it's placed under the hood and is directly connected to the throttle body and also to the ECU or PCM.

What are the symptoms of the failed TAC module?

When the TAC module is not working properly, you will get some issues with the behavior of your vehicle. The changes in the driving patterns will depend on how badly the TAC module is affected. If it's dead, it's likely that you will not be able to drive the car. But these modules don't die that often, they can glitch and malfunction but still allow your car to drive.

Here are the primary symptoms of a faulty TAC module in your car:

• the vehicle hesitates when you press the gas pedal - the reaction comes after a couple of seconds, so driving is not that predictable and comfortable;
• gas mileage drops and your car starts burning much more fuel because all consumption optimization features just don't work now;
• the engine may or may not go to the limp mode and limit the speed or RPM;
• the idling will be harsh and the engine may stall when idling for some time;
• your acceleration will be very uneven and the car will shake like crazy;
• you may notice that the smoke is coming from the tailpipe and the exhaust is a little smelly;
• you will most likely see the check engine light on your dash.

Please keep in mind that all these symptoms may be present with varying degree. You may not notice the MPG drop but you will not overlook that the engine is working harshly and is about to stall each time you stop at a traffic light.

Also, the fact that the check engine light is on is pretty positive for you because now you can easily diagnose the vehicle with the help of the OBD2 scanner and find out the actual reason for the problem. For example, you can see the code P1516 which is most likely connected exactly to the TAC module and is showing problems with this controller.

Why does the TAC module fail?

Before we try to fix this thing, we need to understand why it failed. It's important because sometimes the TAC module itself is completely OK but the problem is with some small sensor or wire that you can't locate so easily.

So, in most cases, these issues will cause TAC module problems and the P1516 code in your vehicle:

• Water intrusion. Like all electronic modules, the TAC module may be damaged by water. Depending on the location of the thing, it may be easy to get it damaged by water just by going into a deep puddle at high speed, for example.
• Wiring issues. One of the wires may have been damaged when the car was maintained in the shop, for example. Or maybe after a minor road accident, the TAC module and its wiring are damaged and need repair.
• Shorted wires. The module may have easily been burnt by a shorted wire or a because of the problem with the voltage in the system.
• Bad gas pedal sensor. Your gas pedal has a sensor that sends the signals directly to the TAC module. If this sensor fails, the ECU may see this as the TAC failure and will throw the P1516 code.
• Throttle body issues. The throttle may be damaged, bent, misshaped, old, or worn, or some sensor in it may not work correctly. This can also make you think that the TAC is in charge of all the problems, but some more investigation is needed.

These are just some of the most common problems that can affect your TAC module in the vehicle and cause your ECU to throw the P1516 code. It doesn't mean that there are no other issues that can cause this problem. Also, the ECU may throw this code just because of some glitch in the ECU itself. For example, the low voltage in the system may cause all kinds of different messages and codes to appear in your vehicle.

Now you know the most common reasons why your TAC may have failed and it will be easier for you to find the actual problem and solve it.

How can you deal with the TAC problem in your car?

To repair the vehicle if it shows all the symptoms of the worn TAC module, you will need to provide the car with the proper inspection first. After this, you will be able to avoid spending money on replacing the parts that actually work well and don't require any attention. You will be able to find the actual problem and solve it.

Here are the most obvious steps you will make on the way to solving the TAC module issue in your vehicle:

1. Diagnose the vehicle

You may need professional help because it's not enough to just see the P1516 code and immediately decide what the problem is. Very often, you will have to test the TAC module which is not that easy to do because even locating this thing under the hood of your car is not always an easy task.

2. Try checking other sensors, too

Don't forget that the proper work of the TAC module depends on the gas pedal sensor and the throttle position sensor. If those two sensors malfunction, your ECU may decide that the problem is connected to the bad TAC unit but actually it's working correctly. The TAC module will cost you more than any of the other sensors included in this chain. So, it's worth checking other sensors, too.

3. Check the TAC

You can go to the dealership and ask them to check the TAC module. Dealers have special equipment and software that can decode the P1516 code and even test the TAC module itself after taking it off the vehicle. Yes, this will cost you some money, but it's still cheaper than buying the new module.

4. Replace the parts that you've found broken

Whether the TAC module is the culprit of your problems or some other parts of your car, replace them with new ones. Electronic modules and sensors can't be repaired. They should just be replaced. And it's really important that you buy OEM parts to ensure they work properly and won't cause new problems right after they are installed.

5. Check if everything works well

Unfortunately, even after proper inspection, you can sometimes replace the wrong part. Maybe, the replaced part was also broken and needed replacement, but there is still one problem that needs more attention. In this case, repeat the inspection and find the actual culprit of the problem with the TAC module.

How can I prevent the TAC module from failing?

Usually, car owners who have already had problems with the TAC module several times, ask how they can prevent them from happening. If this is the case, you should check the location of the module and see if it gets some water damage. Maybe, some coolant leak attacks this module or there is a problem with the fender liner, and water from the road gets directly onto the module.

Also, you may want to check the wiring. A shorted wire may very quickly kill the TAC module. This is one of the common problems that car mechanics overlook. They change the faulty TAC module and forget to check the wiring. A shortage in the system will kill the new TAC and all problems will come back.

Final thoughts

Be careful with electronics in your vehicle. Even a small problem can cost you a lot of money to locate and repair the issue. If you see the check engine light and the OBD2 scanner reads the P1516 code, you better go to specialists and let them figure out what's wrong. There are no good and proper DIY methods of diagnosing and repairing this problem.