Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is having trouble understanding which way the car's wheels are turning because a sensor isn't working right.
The P077A code indicates an issue with the output shaft speed sensor circuit, specifically a loss of the direction signal. This sensor helps the car's computer understand the speed and direction of the transmission output shaft.
The output shaft speed sensor monitors the rotation speed of the transmission's output shaft. This data is crucial for the transmission control module (TCM) to manage gear shifts effectively. A loss of direction signal suggests that the sensor is unable to provide accurate directional data, which can affect transmission performance.
• Erratic or harsh shifting
• Transmission slipping
• Check Engine Light illuminated
• Faulty output shaft speed sensor
• Damaged or corroded wiring/connectors
• Malfunctioning transmission control module (TCM)
Output Shaft: The shaft that transfers power from the transmission to the drivetrain.
Transmission Control Module (TCM): A computer that controls the functions of the transmission.
• Perform a visual inspection of the wiring and connectors.
• Use a multimeter to test the output shaft speed sensor.
• Check for any trouble codes related to the TCM.
• Replace the faulty output shaft speed sensor.
• Repair or replace damaged wiring/connectors.
• Reprogram or replace the TCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect and maintain transmission components.
• Ensure all electrical connections are clean and secure.
• Follow the vehicle's recommended maintenance schedule.
Sensor Issue
• Avoid driving the vehicle until the issue is resolved to prevent further damage.
• Consult a professional mechanic for a thorough diagnosis.
Check with the vehicle manufacturer for warranty coverage on transmission components.
This code has been associated with transmission issues in vehicles with electronic control systems, especially in models with high mileage.
Moderate – Addressing this issue promptly can prevent further transmission damage.
Driving with a malfunctioning transmission sensor can lead to unsafe driving conditions. Address the issue as soon as possible.
• Vehicle should be at operating temperature.
• Perform tests with the vehicle on a lift if possible.
The output shaft speed sensor is typically located on the transmission housing, near the output shaft.
Q: Can I drive with a P077A code?
A: It's not recommended to drive with this code as it can lead to transmission damage and unsafe driving conditions.
Q: How is the output shaft speed sensor tested?
A: A multimeter can be used to test the sensor's electrical resistance and signal output to ensure it's functioning correctly.
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