How Do You Reprogram a Transmission Control Module? Step By Step Guide

Not all car owners know how to reset the TCM, but you are among those who do!

If you have a car, you must know how to handle each of its features. Although knowing how you can reprogram a transmission control module is important when it’s faulty, if you know it before any problem, it won’t cost you anything!

As you know, the transmission control unit or transmission control module (TCM) of the car is the gear box unit. So it’s highly important to keep it functional. This gearbox is a type of automotive that works to handle the automatic transmission in the car.

Sometimes, when TCM gets some fault or damage, it becomes crucial to reprogram it. Besides, reprogramming or resetting it restores the operation and it works as smooth as it was before.

In this article, we shall find out how you reprogram a transmission control module. Let’s know more.

What is TCM in a car?

What is TCM in a car

It’s a mechanical device that handles the speed and power of the vehicle transmission. It also maintains the efficiency of the wheel strength and enhances it for ideal performance. Sometimes, where they are not functioning properly for some reason, it can cause failure which you can restore by reprogramming it, if not you need to replace it.

How do I Reprogram Transmission Control Module

For resetting the TCM you will need a helper and a multimeter. Each car has its own way of manufacturing and the process of resetting TCM may slightly differ. The below mentioned process is suitable for Mazda 3 and Ford.

Here is the simple process of how you reset the transmission module.

  1. First of all, disconnect the negative end of the cable from the battery in the car. This will help you to avoid any electric shock, in any way.
  2. Now disconnect the positive end of the cable from the battery and starter solenoid and take out the transmission control module. If you need to unplug it, do it as it’s easy.
  3. Find the gray wire with the black and white lines on it. It will be on the TCM connector harness.
  4. Now link the multimeter to the wire (mentioned above) and ground it. If you have an automatic or neutral transmission, put it into park.
  5. If the multimeter reads anything under 11 volts, your vehicle is ready to enter the fail-safe mode.
  6. Link the battery cables in reverse manner and leave it on for at least 20 seconds. Then turn off the engine.
  7. Now disconnect the battery cables and leave them while you replace TCM. Carefully put the signal wire connectors back to their original state. After that, you can start your car again.
  8. The TCM should be reset and you can see it performing and functioning normally.

Signs of Bad Transmission Control Module

Transmission control is under the transmission case cover right under the engine control module. If you want to find out the real fault with TCM, it’s best to check out the indication that tells you the possible fault.

Usually, the defective or bad transmission control module has the following signs that impact the effectiveness to control the vehicle in a safe manner.

  • Check Engine Light will turn on to tell you the possible issue.
  • If you have a hard time n shifting the gears, it’s another strong sign. When you hike up the speed, the transmission should also help through the gears.
  • The defect and failure in the TCM will result in decreased fuel economy. The transmission system takes care of ideal fuel consumption and due to the defect in the TM, the engine will get more strain and hence it will use more fuel than required.
  • The TCM performance would be inconsistent if the system is defective.

Reasons Why Transmission Control Module Goes Bad

  1. Defective solenoid is another reason for faulty TCM. If you notice sudden acceleration while driving or inconsistent gear shifts is the reason for the TCM malfunctioning. Also the loose connection in the solenoid or its components will damage the TCM which causes sudden failure.
  2. If the voltages are going suddenly to the circuit board of the TCM, it’s another reason why TCM can become faulty. It can cause burn-out.
  3. When the wiring of the TCM circuit board is faulty it becomes one of the reasons for a bad transmission control module. The circuit board is where the vehicle gets power from, so the lousy wiring or defective internal performance results in the poor TCM output. If the wiring is not attached it can cause breakdown in TCM which you will need to replace.
  4. The overheating of the engine is another reason. The intense engine heat can melt down the electronic components in the transmission control module circuit board.

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