For Mazda 3s that were made in the years of 2006-2014, one of the most common issues is that the transmission control module comes to a point where it doesn’t function quite as it should. While it might seem like the issues you experience could be something else, this is something that you should always consider first. Before we get into the details, let’s take a step back in history. Up until the 1940s, automobiles had standard transmissions. In the 40s, the introduction of automatic transmissions hit the streets and provided drivers with the ability to easily shift their gears without having to do it manually. There was a drawback though, automatic transmissions had to rely on a fluid coupling that would allow the transmission fluid to build up so that it could shift the transmission as necessary. While it served its purpose, it did so by sacrificing the vehicle’s power and fuel efficiency. It wasn’t until the 1980s that automotive technology started to evolve and embrace transmissions that were electronically controlled instead of embracing dated methods. During the 90s, a transmission control unit dedicated to helping the transmission shift increased in usage. Doing so helped automakers embrace an increased amount of power and more efficiency when it comes to fuel consumption. While these were great strides for the automotive industry, it does have its setbacks such as failing after a certain amount of time. Over the years of providing vehicle owners with refurbished parts and service in our shop located in the Atlanta area, we have seen it to be more common with 2006-2014 Mazda 3s, and buying a new one can become rather costly. With that said, this guide will take you through all the basics of what a TCM is, Mazda 3 TCM issues, and how you could save $700 or more if you have to replace your Mazda 3 TCM. If you have any further questions, don’t hesitate to reach out to us and we’ll be there to help you every step of the way.
What is a transmission control module (TCM)?
Basically, a TCM is an electronic device that helps tell the transmission how it needs to shift depending on the particular situation (going uphill or downhill) as well as the speed that is being maintained. It works closely with many of the other parts of your vehicle as well as other sensors to help ensure a smooth ride during each and every trip. It also helps determine how much power the vehicle needs to produce as well as how much fuel is used. You will only find a transmission control module in vehicles with automatic transmissions, as it basically replaces the need for the driver to control the clutch when they’re shifting gears. There are more advanced TCMs on the market that will help remember your driving habits. Doing so will allow it to store information about them and know how it needs to react in terms of gear adjustment. If your TCM goes bad, it could lead to a variety of issues (at times making it difficult to diagnose) which will be covered in the next section.How to Know If Your TCM Is the Root of Your Troubles
Knowing the issues that a bad TCM in your Mazda 3 could cause will help you understand if it’s truly the root of your problems. Preventing you from having to make unnecessary repairs, or even worse, let it sit because you think that it’s something more serious than what it really is.Common Failures:
- Strong "kick" when switching automatic grip from position "P" to position "R"
- Indication on the dash "Check Engine" , "AT" , "ABS" , "Slippery Road" (ESP) etc.
- Gearbox does not go to "manual mode"
- The car goes in emergency mode only
- Check Engine light and AT lights are on
- Vehicle stays in 3rd gear only (safe mode)
- Hard "kick" on "drive" and "reverse"
- Hard shifting on gears
· The first sign is the most obvious, your check engine light is on.
While the check engine light for a Mazda 3 could mean a number of things, one of those issues could be the transmission control module itself. If you find that your check engine light comes on it should lead you to either performing a diagnostic scan yourself (with a reliable diagnostic scanner that can produce you with the error codes) or by taking it into a shop (such as the one we have in the Atlanta area) to have a mechanic run the scan and let you know what’s going on. SOME OF THE CODES THAT ARE KNOWN TO SURFACE WITH MAZDA 3 TCM ISSUES ARE:- Error DTC U0073 - control Module Communication Bus "A" is off (the e-Data bus control is disabled)
- Error DTC U0100 - Lost Communication with ECM/PCM "a" error (data bus, engine control module (ECM) "A"-no link)
- Error DTC U0101 - Lost Communication with TCM (data bus, transmission control module (TCM) - no link)
- Error DTC P0715 - Input/Turbine Speed sensor "A" Circuit (the rotation frequency sensor of the input shaft of automatic gearbox (Hydrotransformer turbine)- Electrical circuit failure)
- Error DTC P0720 - Output Speed sensor Circuit error (shaft rotation frequency sensor - fault of electrical circuit)
- Error DTC P0744 - Torque Converter Clutch Circuit Intermittent (Electromagnetic valve coupling of a hydro transformer - unreliable pin of the electrical circuit)
- Error DTC P0745 - Pressure control solenoid valve manifold "A" (Gearbox Electromagnetic fluid pressure control valve - electric circuit fault)
- Error DTC P0748 - Pressure control solenoid valve manifold "A" Electrical Gearbox (electromagnetic pressure control valve - electrical malfunction)
- Error DTC P0753 - Shift solenoid valve manifold "A" Electrical (Gearbox electromagnetic valve A - electrical malfunction)
- Error DTC P0758 - Shift solenoid valve manifold "B" Electrical (Gearbox electromagnetic valve B in - electrical malfunction)
- Error DTC P0763 - Shift solenoid valve manifold "C" Electrical (Gearbox electromagnetic valve C in - electrical malfunction)
- Error DTC P0768 - Shift solenoid valve manifold "D" Electrical (Gearbox electromagnetic valve D - electrical malfunction)
- Error DTC P0773 - Shift solenoid valve manifold "E" Electrical (Gearbox electromagnetic valve E in - electrical malfunction)
- Error DTC P0778 - Pressure control solenoid valve manifold "B" electrical (electromagnetic valve B in pressure control - electrical malfunction)
- Error DTC P0791 - Intermediate Shaft speed sensor "A" Circuit (intermediate shaft frequency sensor - failure of the electrical circuit)
- Error DTC P0841 - Transmission Fluid Pressure sensor/Switch "A" error - Circuit Range/performance (sensor A of the pressure of the work fluid of gearbox - band/function)
- Error DTC P0882 - TCM Power Input Signal Low (Gearbox electronic control module - low power supply voltage)
- Error DTC P0883 - TCM Power Input Signal Low (Gearbox electronic control module - high power supply voltage)
- Error DTC P0884 - TCM Power Input Signal Intermittent (Gearbox electronic control module (TCM), input power signal - unreliable pin of the electrical circuit)
- Error DTC P2709 - Shift solenoid valve manifold "F" Electrical (electromagnetic valve F gear switches - electrical malfunction)