P0702 Electrical fault in transmission control system

P0702 – OBD-II Trouble Code Technical Description

Trouble code P0702 indicates that the PCM has detected a problem with the automatic transmission control system.

What does the fault code mean P0702?

Trouble code P0702 indicates a problem in the automatic transmission control system (ATC). It indicates that the engine control module (PCM) has received incorrect readings from one of the sensors, solenoid valves, or transmission switches. This can cause the transmission to operate incorrectly, possibly with harsh or delayed gear changes. Error codes may also appear along with this code. P0700 и P0701.

Possible reasons

Some possible reasons for the P0702 trouble code:

• Faulty speed sensors: A malfunction of one of the speed sensors, such as the engine rotation speed sensor or the automatic transmission output speed sensor, can cause this code to appear.
• Problems with solenoid valves: Failure of the solenoid valves that control gear shifting in the transmission can also cause P0702.
• Transmission switch malfunction: Problems with the Transmission Range Sensor, which detects the position of the gear selector lever, may also be the cause of this error.
• Problems with wiring and connections: Damage or breaks in the wiring, as well as improper connections between components of the transmission control system, can cause the P0702 code.
• Problems with the automatic transmission control module (TCM): A malfunction in the transmission control module itself can cause the data to be misinterpreted and cause this error to appear.
• Other transmission problems: There may be other transmission problems such as mechanical failures, worn parts, etc. that can cause the P0702 code.

To accurately determine the cause of error P0702, it is recommended to diagnose the vehicle using an OBD-II scanner and additional tests.

What are the symptoms of a fault code? P0702?

Here are some possible symptoms that may accompany the P0702 trouble code:

• Gear shifting problems: Difficulty or delay when shifting gears may be one of the first symptoms. This may manifest itself as harsh or unusually smooth gear changes.
• Jamming in one gear: The vehicle may stay in one gear and not shift, or may have difficulty shifting.
• Uneven engine operation: The engine may experience uneven operation during acceleration or idling.
• Check Engine Light Illuminates: When P0702 is detected, the Check Engine light on your dashboard may come on.
• Emergency protection mode: In some cases, the vehicle may go into emergency mode to prevent possible damage to the transmission.
• Other error codes: In addition to the P0702 code, other transmission or engine management system related error codes may also appear.

These symptoms may occur to varying degrees and under different vehicle operating conditions. It is important to have the problem diagnosed and repaired by a qualified mechanic as soon as possible to avoid further damage and ensure the safe operation of your vehicle.

How to diagnose a fault code P0702?

The following steps are recommended to diagnose DTC P0702:

1. Checking Error Codes: Using an OBD-II scanner, read any error codes that may be stored in the engine control module (PCM) or transmission control module (TCM). This will help determine if there are other problems that may be related to the transmission.
2. Checking the status of speed sensors: Check the operation of the engine and transmission speed sensors. This may include checking their resistance or checking the signals for incorrect values.
3. Checking the solenoid valves: Carry out diagnostics on the solenoid valves inside the transmission to identify any faults.
4. Checking the gearbox switch: Check the operation of the Transmission Range Sensor for abnormal signal or mechanical damage.
5. Checking wiring and connections: Inspect the electrical wiring and connectors associated with the transmission control system for damage, corrosion, or breaks.
6. Diagnostics of the automatic transmission control module: If necessary, perform diagnostics on the Transmission Control Module (TCM) to ensure that it is operating properly and that sensor data is being interpreted correctly.
7. Transmission testing: If no other causes are found, more detailed testing of the transmission itself may be required, including checking its pressure, oil condition, etc.
8. Software update: In some cases, a PCM or TCM software update may be required to resolve the issue.

After diagnosing and determining the cause of the P0702 code, you should take the necessary steps to correct the problem, including replacing sensors or valves, repairing wiring, or replacing the automatic transmission control module, if necessary.

Diagnostic errors

When diagnosing DTC P0702, the following errors may occur:

• Skip Speed ​​Sensor Test: Failure to check the condition of the engine and transmission speed sensors may result in an undiagnosed problem with one of these sensors.
• Unaccounted for electrical problems: If wiring and connectors are not fully inspected for breaks, corrosion, or poor connections, it may result in undiagnosed electrical problems.
• Misinterpretation of data: Failures in interpreting data from sensors or solenoid valves can lead to misdiagnosis and replacement of components that do not actually require replacement.
• Software problemsNote: Failure to check for software updates for the PCM or TCM may result in undiagnosed problems that may be corrected by updates.
• Incorrect transmission diagnosis: Failure to fully diagnose the transmission itself may result in problems related to mechanical or hydraulic components being missed.
• Unaccounted for other error codes: Sometimes the P0702 code can be the result of other problems that were not detected or accounted for during the diagnosis.

To avoid these errors, it is important to perform a complete and systematic diagnosis, including checking all components associated with the transmission control system, as well as ensuring that the data from the OBD-II scanner is correctly interpreted.

How serious is the fault code? P0702?

Trouble code P0702, which indicates problems with the automatic transmission control system (ATC), can be serious because it can cause the transmission to malfunction and create unsafe driving conditions. Depending on the specific cause of this code, symptoms can range from mild hesitancy when shifting gears to complete transmission inoperability. If the problem is not corrected, it can result in severe transmission damage and potentially dangerous driving conditions. Therefore, it is important to immediately begin diagnosing and fixing the problem when the P0702 code appears.

What repair will help eliminate the code? P0702?

Repair to resolve DTC P0702 will depend on the specific cause of the problem, several possible actions include:

1. Replacing or repairing speed sensors: If the problem is related to a malfunction of one of the engine or transmission speed sensors, then they can be replaced or repaired.
2. Replacing solenoid valves: If the problem is with the solenoid valves inside the transmission, they can be replaced.
3. Replacing the transmission switch: If the Transmission Range Sensor fails, it can also be replaced.
4. Repair of electrical wiring and connections: If the problem is an open, corroded or loose connection in the electrical wiring or connectors, it can be repaired or replaced.
5. Updating the software: In some cases, the problem may be resolved by updating the PCM or TCM software to the latest version.
6. Transmission diagnostics and repair: If no other causes are found, transmission diagnostics and repairs may be required to identify and correct the problem.

It is important to contact a qualified mechanic or service center to perform a diagnosis and determine the best course of action to resolve the problem based on your vehicle's specific circumstances.

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P0702 – Brand-specific information

Trouble code P0702 is a general error code that indicates problems with the automatic transmission control system (ATC), below is a list of several car brands with its meaning:

• Toyota, Lexus, Scion: Incorrect speed sensor readings.
• Honda Acura: Error in speed sensor or transmission switch signals.
• Ford, Lincoln, Mercury: Problems with solenoid valves or speed sensors.
• Chevrolet, GMC, Cadillac, Buick: Incorrect speed sensor readings or electrical wiring problems.
• BMW, MINI: Incorrect signals from speed sensors or problems with automatic transmission solenoid valves.
• Mercedes-Benz: Incorrect speed sensor readings or faulty solenoid valves.
• Volkswagen, Audi, Porsche: Problems with the transmission switch or solenoid valves.

Given the many makes and models of vehicles, this list may not cover all possible problems. Therefore, it is always recommended to consult the service manual for your specific vehicle make and model and contact a professional for accurate diagnosis and repair.