Transaxle Control System Malfunction (P0700, Causes + Solutions)

transaxle control system malfunction

When it comes to the smooth operation of your vehicle, the transaxle control system plays a crucial role. However, if you encounter an error code like P0700, it indicates a problem with the system.

In this comprehensive guide, we will explore the causes and resolutions of a transaxle control system malfunction, helping you understand the issue and find solutions to get your vehicle back on the road.

Understanding the Transaxle Control System

Before delving into the causes and resolutions, let’s first grasp the concept of the transaxle control system. The transaxle, a combination of the words “transmission” and “axle,” integrates the transmission, differential, and drive axle into a single assembly.

It transfers power from the engine directly to the axles, eliminating the need for a large drivetrain. The transaxle control module (TCM) acts as the brain of the automatic transaxle, monitoring engine conditions to determine the optimal gear for the vehicle.

Causes of Transaxle Control System Malfunction

Several factors can contribute to a transaxle control system malfunction. Let’s explore the most common causes:

1. Low Transmission Fluid

Insufficient transmission fluid can hamper the proper functioning of various transmission components. When the fluid level is low, parts like the torque converter won’t operate with sufficient fluid pressure. As a result, the TCM detects the issue and triggers a transaxle control system malfunction.

2. Weak Battery

The TCM relies on input from numerous sensors in the vehicle. When these sensors fail or operate below optimal levels, the TCM struggles to control the transmission settings effectively.

A weak battery can lead to reduced sensor functionality, causing the TCM to detect them as offline and triggering the error code.

3. Defective Shift Solenoids

Shift solenoids are responsible for controlling the current gear setting in the transmission. Over time, these solenoids can deteriorate or become stuck, impeding the TCM’s ability to change gears smoothly. Consequently, the transaxle control system malfunction error may appear, accompanied by symptoms like gear sticking or sluggish shifting.

4. Issues with TCM and ECM Connections

The TCM and ECM (engine control module) must communicate seamlessly to maintain the transaxle’s optimal performance. However, loose connections, faulty wiring, or short circuits can disrupt this communication, leading to the transaxle control system malfunction error.

Thoroughly inspecting these connections and addressing any issues is crucial for resolving the problem.

5. Faulty Crankshaft Position Sensor

Although not directly related to the transmission, the TCM relies on accurate information about the camshaft position to determine the optimal gear settings.

A faulty crankshaft position sensor can impede the TCM’s ability to make precise adjustments, resulting in the transaxle control system malfunction error.

6. Defective TCM

While rare, a malfunctioning TCM can be the root cause of the transaxle control system malfunction. If the TCM is damaged, it loses control over the transaxle, leading to difficulties or unpredictable shifting.

In such cases, replacing the faulty TCM becomes necessary for restoring normal operation.

Read also >> Engine Control Malfunction (Causes, Solutions + More)

Read also >> Transmission Malfunction (Main Transmission Failure + More)

Resolving Transaxle Control System Malfunction

Now that we have explored the causes, let’s discuss the potential resolutions for a transaxle control system malfunction:

1. Checking and Topping Up Transmission Fluid

Start by inspecting the transmission fluid level. Using the dipstick, check if the fluid is at an adequate level. If it’s low, topping it up can alleviate the issue. Ensure the transmission fluid is clean; if it appears dirty or discolored, a fluid change might be necessary.

2. Charging or Replacing the Battery

If you suspect a weak battery, measure its voltage using a multimeter. A voltage below 12.6V indicates a weak battery that requires charging. If the battery is old or unable to hold a charge, replacing it with a new one is recommended.

3. Repairing or Replacing Faulty Wiring

Thoroughly inspect the wiring connections between the TCM and ECM. Look for any signs of damage or loose connections. Replace any damaged wiring to ensure uninterrupted communication between the modules.

4. Addressing Shift Solenoid Issues

If shift solenoids are identified as the cause of the malfunction, it’s advisable to seek professional assistance. Due to the intricate nature of the transmission’s valve body, repairs or replacements should be handled by experienced technicians.

5. Resolving TCM and ECM Communication Issues

If the TCM and ECM connections are compromised, identifying and rectifying the underlying wiring or connection issues is crucial.

Ensuring a seamless flow of communication between these modules will resolve the transaxle control system malfunction.

6. Repairing or Replacing the Crankshaft Position Sensor

If a faulty crankshaft position sensor is identified, it’s best to consult an automotive professional for repair or replacement.

Accessing and replacing this sensor often requires intricate procedures that require experience and expertise.

7. Replacing the TCM

In rare cases where the TCM is damaged beyond repair, replacing it becomes necessary. A faulty TCM can severely impact the transaxle’s control system, resulting in difficulties with shifting and overall performance.



A transaxle control system malfunction can disrupt the smooth operation of your vehicle’s transmission. By understanding the potential causes and exploring appropriate resolutions, you can address this issue promptly.

Whether it’s topping up transmission fluid, addressing wiring issues, or replacing faulty components, taking the necessary steps will help restore your vehicle’s optimal performance.

If you encounter a transaxle control system malfunction, consult a qualified technician to diagnose and resolve the issue effectively.

Steve P.

Steve is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Riviera. Steve is based in Boise, Idaho.

Recent Posts

error: Content is protected !!