To fix the Transmission Control System MIL Request – P0700 code, first, check the transmission fluid level, then top off or replace it if necessary. Next, inspect the wiring harness for damage or loose connections and repair any faults. Clean the electrical contacts of the TCM and related components using contact cleaners. If needed, address issues with the valve body, responsible for fluid flow control.
There are lots of things to know when fixing a transmission control system MIL request. Go through this whole article to have proper knowledge of how to fix the transmission control system MIL request- P0700 code.
What Are The Symptoms for P0700 Code
The P0700 code is a generic transmission error code that indicates a problem with the transmission control system. Here are some common reasons and symptoms for the P0700 code:
- Vehicle hesitation
- Issues when changing gears
- Stalling
- Rough driving
- Noticeable reduction in gas mileage
- Transmission slipping
- Harsh shifting
- Illuminated check engine light
It is important to note that the P0700 code is a broad code, and there are usually other transmission codes stored in conjunction with it. Therefore, it is recommended to diagnose and fix any other transmission problems before attempting to fix the P0700 code.
Seeking professional help from a certified mechanic or transmission specialist is also recommended if you are unable to diagnose and fix the problem yourself.
Reason and Solution for Control System MIL Request- P0700 Code
There are lots of reasons behind this Control System MIL Request- P0700 Code in your car. Let’s have an overview of these reasons and solutions in the following table:
| Issues | Solution |
| Malfunction within the Transmission Control System | – Inspect the Transmission Control System to identify the root cause. – Repair or replace the wiring harness with damaged connections. – Replace the transmission if the problem is severe. |
| Dirty or Fouled TCM | – Thoroughly clean the TCM using electronic component cleaners or contact cleaners. |
| Faulty TCM Connectors or Wiring | – Use a multimeter to assess connectors for voltage or continuity issues. – Replace the wire connected to problematic connectors if necessary. |
| Defective Shift Solenoids | – Replace malfunctioning shift solenoids. – Inspect the wiring harness for damage and repair any faulty connections. |
| Low or Dirty Transmission Fluid | – Perform a complete fluid flush if the fluid appears dirty or contaminated. |
| Slipping Torque Converter | – Check transmission fluid level and quality and fill or flush as needed. – Repair any damaged wires identified during diagnosis. |
| Defective Valve Body | – Consider repair by replacing faulty solenoids, gaskets, or damaged components. |
| Defective transmission fluid temperature Sensor | – Replace the defective transmission fluid temperature sensor. |
Some necessary tools are needed to fix this MIL request -P0700 code. So the following tools need to be managed.
Tools needed
- A flashlight to have a clear vision
- A Phillips screwdriver
- A universal socket set
- Electrical contact cleaner
- A multimeter
- An OBD2 code scanner
Issue 1: Malfunction within the Transmission Control System
Symptoms
- Transmission slipping
- Harsh shifting
- An illuminated check engine light
Reason
The P0700 code indicates that a vehicle’s management software has detected a malfunction within the transmission control system.
TCM is responsible for monitoring the sensors and actuators in the transmission and analyzing the data to ensure that the transmission is operating correctly. If the TCM detects a problem, it will trigger the MIL (Malfunction Indicator Lamp) to illuminate and store the P0700 code.
A malfunction within the Transmission Control System can cause the TCM to send incorrect signals to the ECM. Then it can trigger the MIL request and cause the P0700 code to appear.
Solution
Follow the steps to solve the issue.
- Inspect the transmission control system to identify the root cause of the problem. It is located in the back of the transmission. In case you don’t find it, refer to your car’s instruction manual to find it. If the TCM is faulty, it may need to be replaced.
Note: The estimated cost for TCM replacement is approximately $750 to $808.
It is important to note that the specific solution needed may vary depending on the root cause of the problem.
Issue 2: Dirty or Fouled TCM
Symptoms
- Delayed or harsh shifting
- Erratic behavior
- The activation of fault codes like the P0700 code
Reason
Over time, the TCM itself can accumulate dirt, grime, or other contaminants, which can hinder its proper functioning and communication abilities. This can lead to disruptions in the control and coordination of the transmission system.
Solution
To address a dirty or fouled TCM, the following steps are typically taken:
- Visual Inspection
A mechanic or technician will visually examine the TCM for any visible signs of dirt, debris, or corrosion. This inspection may involve removing the TCM cover or accessing it through the vehicle’s interior.
- Cleaning
If the TCM is found to be dirty or fouled, it will need to be cleaned thoroughly. Specialized electronic component cleaners or contact cleaners may be used to remove dirt, grime, or other contaminants from the TCM. Care must be taken to follow the manufacturer’s recommendations and avoid damaging any sensitive electronic components during the cleaning process.
- Reinstallation and Testing:
Once the TCM has been cleaned, it will be reinstalled in its original position and securely connected. The vehicle will then be tested to ensure that the TCM is functioning properly and communicating effectively with other transmission components. This may involve running diagnostic scans or test drives to monitor the transmission’s performance and verify that the previous issues have been resolved.
Issue 3: Faulty TCM Connectors or Wiring
Reason
Faulty TCM connectors or wiring can cause communication issues within the transmission control system (TCS). This can lead to the TCM sending incorrect signals to the ECM, potentially triggering a MIL request and causing the P0700 code to appear.
Issues with the connectors or wiring responsible for linking various components within the transmission control system can result in communication errors or malfunctions. The TCM is responsible for monitoring sensors and actuators in the transmission, analyzing data to ensure the transmission operates correctly.
Solution
The solution for Faulty TCM Connectors or Wiring is mentioned below:
Safety Tip: It is crucial to prioritize safety when working with electrical components. Disconnect the vehicle’s power source before undertaking any repairs or modifications.
Inspect Connections
- Thoroughly examine the connections between the power controller and valves in the transmission control system.
- Ensure the connectors are securely attached and properly seated.
Use a Multimeter
- Utilize a multimeter to assess the connectors.
- Set the multimeter to the appropriate settings to measure voltage or continuity.
Identify Problematic Connectors
- Look for connectors that do not display power or continuity readings.
- These connectors indicate potential issues with the wire connecting them.
Replace Faulty Wire
- To resolve the problem, replace the wire connected to the problematic connectors.
- Disconnect the wire carefully from both ends, following safety precautions.
- Install a new wire of the appropriate gauge and length.
- Ensure the new wire is securely connected to the respective connector points.
Issue 4: Defective Shift Solenoids
Reason
Unpredictable gear shifts are a common sign of transmission solenoid failure. Your car may unexpectedly switch to another gear while driving at a constant speed.
Solution
- Scan for codes: Use the OBD scanner tool to check for other transmission codes that may be stored in conjunction with the P0700 code. This will help you identify the root cause of the problem.
- Check the transmission fluid: Low or dirty transmission fluid can cause transmission problems that trigger the P0700 code. Check the fluid level and condition, and add automatic transmission fluid if necessary.
- Replace the shift solenoids: Malfunctioning shift solenoids can cause the P0700 code to appear. Check the solenoids for proper operation, and replace them if necessary. Replacing the transmission solenoid usually takes around 2-4 hours of labor.
Issue 5: Low or Dirty Transmission Fluid
Symptoms
- Abrasive conditions
- Increased friction
- Potential damage to internal parts such as gears.
Reason
Insufficient transmission fluid levels can lead to a lack of lubrication and cooling within the transmission system. You may face increased friction, excessive heat, and accelerated wear and tear on critical transmission parts.
Also, dirty transmission fluid, contaminated with particles or debris, can hinder the fluid’s ability to effectively lubricate and cool the transmission components.
Solution
To address inadequate fluid levels or dirty fluid in the transmission system, the following solutions are typically recommended:
- Check Fluid Levels:
Ensure that the transmission fluid level is within the recommended range. If the level is low, top it off with the appropriate type of transmission fluid as specified in the owner’s manual.
- Fluid Flush and Replacement:
If the transmission fluid appears dirty, contaminated, or has not been changed for an extended period, it is advisable to perform a complete fluid flush. This process involves draining the old fluid and replacing it with fresh, manufacturer-approved transmission fluid.
Note: This transmission fluid repair generally costs between $50 to $200.
- Filter Replacement:
In some transmission systems, there is a filter that helps remove contaminants from the fluid. If the filter becomes clogged or dirty, it can hinder fluid flow and contribute to transmission issues.
As part of regular maintenance or during a fluid flush, it is recommended to replace the transmission filter to ensure proper filtration and fluid cleanliness.
Issue 6: Slipping Torque Converter
Reason
A slipping torque converter can have significant implications for the performance and functionality of the transmission system. When a torque converter slips, it means that there is a loss of power transfer efficiency between the engine and the transmission.
This can occur due to various reasons, such as worn internal components, insufficient fluid pressure, or damaged seals. As a result, the transmission may experience several issues that can trigger the Malfunction Indicator Lamp (MIL) request.
Solution
Diagnosing and Replacing a Slipping Torque Converter:
1. Diagnosis:
- A slipping torque converter can result in noticeable symptoms such as engine RPM fluctuations, delayed or harsh shifting, and decreased acceleration. If you suspect a slipping torque converter, follow these steps to diagnose the issue:
2. Check Transmission Fluid:
- Begin by checking the transmission fluid level and quality. Ensure it is at the correct level and not contaminated or burnt, as previously discussed.
3. Perform a Stall Test:
- A stall test can help diagnose torque converter issues. To perform this test:
- Find a safe, open area (such as an empty parking lot) where you can safely accelerate your vehicle.
- Bring your vehicle to a complete stop.
- Apply the parking brake and keep your foot on the brake pedal.
- Shift the transmission into Drive and gently apply the accelerator pedal.
- Pay attention to the engine RPM on the tachometer.
- The engine RPM should gradually rise without significant slippage. If the RPM increases sharply or there is excessive slippage, it may indicate a problem with the torque converter.
4. Transmission Diagnostic Scan:
- Use a diagnostic scan tool to retrieve trouble codes from the Transmission Control Module (TCM). Specific codes related to the torque converter may provide valuable information about the issue.
Replacing the Torque Converter:
1. Vehicle Preparation:
- Ensure your vehicle is safely raised and securely supported on jack stands.
Disconnect the battery to prevent electrical hazards.
2. Transmission Removal:
- Removing the torque converter typically involves partially or fully removing the transmission. This is a complex and labor-intensive task best left to experienced mechanics. It often includes:
- Draining the transmission fluid.
- Disconnecting wiring harnesses, sensors, and linkages.
- Removing the transmission pan and valve body.
- Detaching the torque converter from the flexplate.
3. Torque Converter Replacement:
- Replace the old torque converter with a new or remanufactured one designed for your specific vehicle make and model.
- Ensure proper alignment and engagement with the transmission input shaft.
4. Transmission Reinstallation:
- Reinstall the transmission, ensuring all connections, bolts, and brackets are properly secured.
5. Fluid Refill and Testing:
- Refill the transmission with the appropriate transmission fluid, following manufacturer specifications.
- Perform a test drive to verify that the slipping issue has been resolved.
- Given the complexity of replacing a torque converter, it is highly recommended to entrust this task to a qualified automotive technician or transmission specialist to ensure the job is performed correctly and safely.
Note: Misidentifying the problem as a mechanical issue with the transmission itself can be expensive and failure to fix the problem.
Therefore, it is recommended to diagnose the specific cause of the slipping converter before attempting any repairs. A certified mechanic can perform the Check Engine Light diagnostic and provide an upfront quote for the recommended fix.
Issue 7: Defective Valve Body
Symptoms
- Knocking or slamming noises during gear changes
- Transmission slipping
Reason
The valve body is a crucial component of the transmission system that controls the flow and direction of hydraulic fluid. That in turn affects gear shifting and other transmission operations. A damaged or faulty valve body in the transmission can trigger the MIL request and result in the appearance of the P0700 code.
Solution
In some cases, a simple repair may be sufficient, while in others, a complete replacement may be necessary. So the quick fix that you can do is,
- Valve Body Repair:
If the problem is isolated to certain components within the valve body, repair may be a viable option. This could involve replacing faulty solenoids, gaskets, or other damaged parts. The cost of repair would depend on the extent of the damage and the cost of the replacement parts.
- Valve Body Replacement:
If the valve body is severely damaged or repairing it is not feasible, replacement becomes the preferred solution. The cost of valve body replacement can vary widely based on the make and model of the vehicle.
Issue 8: Defective Transmission Fluid Temperature Sensor
Symptoms
- Poor fuel economy
- Engine overheating
- An illuminated check engine light
Reason
A faulty transmission fluid temperature sensor can cause the P0700 code to appear. The transmission temperature sensor is responsible for monitoring the temperature of the transmission fluid and sending that information to the engine control module (ECM).
If the sensor is not working correctly, it can cause the ECM to send incorrect signals to the TCM. It can trigger the MIL request and cause the P0700 code to appear.
Solution
Below is some potential ways to address a faulty transmission fluid temperature sensor triggering the P0700 code:
transmission fluid temperature Sensor Replacement
When dealing with a defective transmission fluid temperature sensor, the most effective solution is to replace the sensor. To DIY this problem follow these steps-
- Prepare the Vehicle
- Locate the transmission fluid temperature Sensor
- Drain the fluid
- Disconnect the Electrical Connector
- Remove the Old Sensor
- Install the New Sensor
- Reconnect the Electrical Connector
- Test and Verify
Use this visual guide to get insight on replacing it properly.
Which Car Models Are Affected by P0700 Code
The P0700 code is a generic transmission error code that applies to all makes and models of vehicles. The following car models are known to be affected by the P0700 code:
- Toyota
- Nissan
- Chevrolet
- BMW
- Audi
Mistakes That Should Be Avoided While Fixing This Issue
One of the most common errors during the diagnosis of symptoms related to a P0700 code is incorrectly identifying the problem. Most of the time people identify it as a mechanical issue within the transmission itself.
This mistake can be costly, as transmission repairs are significantly more expensive than replacing a single computer component. Not only does misdiagnosing the problem fail to resolve the issue, but it also leads to unnecessary expenses on unnecessary repairs.
If you suspect that the (TCM) is the cause of your vehicle’s troubles, it’s essential to have the diagnostic trouble codes (DTCs) read. Identifying a TCM problem allows for a quick and easy fix.
Conversely, if the issue lies elsewhere, you can be ensured that you’ve correctly addressed the mechanical problem.
Another common mistake is neglecting to thoroughly inspect the wiring harness. Overlooking this necessary step may result in replacing a perfectly functional TCM while leaving the actual underlying issue unresolved.
FAQs
What Happens If You Unplug TCM?
Unplugging the Transmission Control Module (TCM) can be a safety measure during diagnosis and repair to prevent potential damage to the module. Disconnecting the TCM from its power source can avoid any risk of the metal case coming into contact with the battery voltage.
Can I Drive with a Bad TCM?
Driving with a bad Transmission Control Module (TCM) is not recommended as it can lead to unpredictable shifting behaviors and potential safety hazards. If you observe any signs or symptoms indicating TCM issues, it’s crucial to address the problem promptly.
What Happens If TCM Is Not Programmed?
If the Transmission Control Module (TCM) is not properly programmed or becomes faulty, it can result in unpredictable shifting behavior, posing significant safety risks. Additionally, it may lead to reduced fuel efficiency and sluggish acceleration, creating less-than-ideal driving conditions.
Conclusion
Now you know how to fix the transmission control system MIL request- P0700 code.
Remember, the transmission control system is a critical component of the vehicle, and improper handling can lead to safety risks, and transmission damage. If you are unsure about any aspect of the repair process, it’s always best to consult a professional mechanic or repair service.
