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 reading the speed of a part that helps the car move. It's like trying to listen to music with headphones that have a broken wire.
The P077C code indicates that the transmission control module (TCM) has detected a low voltage signal from the output shaft speed sensor circuit.
The output shaft speed sensor measures the rotational speed of the transmission's output shaft and sends this information to the TCM. A low circuit signal suggests a problem with the sensor, its wiring, or the TCM itself, affecting the transmission's ability to shift gears properly.
• Check Engine Light is on
• Transmission shifts improperly
• Decreased fuel efficiency
• Faulty output shaft speed sensor
• Damaged or corroded wiring or connectors
• Faulty transmission control module (TCM)
Transmission Control Module (TCM): A computer that controls the transmission's functions.
Output Shaft: The part of the transmission that transfers power to the wheels.
• Use an OBD-II scanner to confirm the P077C code.
• Inspect the output shaft speed sensor and its wiring for damage or corrosion.
• Test the sensor's electrical output using a multimeter.
• Replace the output shaft speed sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Replace the transmission control module 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 connectors and wiring are free from corrosion.
• Follow manufacturer-recommended service intervals.
Sensor Issue
• Do not ignore the Check Engine Light.
• Seek professional diagnosis if unsure about repairs.
Check with your vehicle's manufacturer for specific warranty coverage related to transmission components.
The P077C code has been associated with sensor issues in vehicles with automatic transmissions since the implementation of OBD-II systems.
Moderate – Driving with this code may lead to transmission performance issues and should be addressed promptly.
Ignoring transmission issues can lead to safety hazards on the road. Always ensure your vehicle is in safe operating condition.
• Vehicle at operating temperature
• Transmission in drive mode
The output shaft speed sensor is typically located on the transmission near the output shaft.
Q: Can I drive with a P077C code?
A: It's possible, but not recommended as it may cause further transmission damage.
Q: How do I reset the P077C code?
A: After repairs, use an OBD-II scanner to clear the code from the vehicle's computer.
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