P077D GMC Code - Transmission Output Speed Sensor Circuit High Voltage
Quick Answer
The Output Speed Sensor (OSS) is a hall-effect type sensor. Common causes include Faulty Transmission Output Speed Sensor (OSS), Transmission Output Speed Sensor harness is open or shorted, Transmission Output Speed Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P077D GMC indicates Transmission Output Speed Sensor Circuit High Voltage.
- Common causes
- Common causes include Faulty Transmission Output Speed Sensor (OSS), Transmission Output Speed Sensor harness is open or shorted, Transmission Output Speed Sensor circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P077D GMC Description
The Diagnostic Trouble Code (DTC) will be set when the TCM detects the vehicle speed sensor signal circuit voltage is 4.75 V or greater for 0.8 s.
What are the Possible Causes of the DTC P077D GMC?
- Faulty Transmission Output Speed Sensor (OSS)
- Transmission Output Speed Sensor harness is open or shorted
- Transmission Output Speed Sensor circuit poor electrical connection
- Faulty Transmission Control Module (TCM)
How to Fix the DTC P077D GMC?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P077D GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P077D GMC code?
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Information for Specific GMC Models
- P077D 2014 GMC Sierra — Transmission Output Speed Sensor Circuit High Voltage
- P077D 2015 GMC Sierra — Transmission Output Speed Sensor Circuit High Voltage
- P077D 2016 GMC Sierra — Transmission Output Speed Sensor Circuit High Voltage
- P077D 2017 GMC Sierra — Transmission Output Speed Sensor Circuit High Voltage
- P077D 2018 GMC Sierra — Transmission Output Speed Sensor Circuit High Voltage
Frequently Asked Questions about P077D GMC Code
1. What are the common symptoms of OBDII code P077D GMC (Transmission Output Speed Sensor Circuit High Voltage)?
- Common symptoms include erratic shifting behavior, transmission slipping, and the transmission going into limp mode.
2. What are the possible causes of OBDII code P077D GMC?
- The code P077D GMC may be caused by a faulty transmission output speed sensor, damaged wiring or connectors in the sensor circuit, or issues with the transmission control module.
3. How can I diagnose the cause of OBDII code P077D GMC?
- You can diagnose the cause of the code by performing a visual inspection of the sensor and its wiring, conducting a multimeter test to check for proper sensor operation, and using a scan tool to retrieve and interpret the code.
4. What is the potential risk of driving with OBDII code P077D GMC active?
- Driving with the P077D code active may lead to further damage to the transmission and other drivetrain components. It is recommended to address the issue promptly to prevent costly repairs.
5. Can I repair OBDII code P077D GMC myself?
- Depending on your experience level and access to tools, you may be able to repair the issue causing the code. However, it is recommended to consult a professional mechanic for accurate diagnosis and proper repair.
6. How much does it typically cost to repair OBDII code P077D GMC?
- The cost of repairing the P077D code can vary depending on the underlying cause. Costs may range from $100 to $500, including parts and labor.
7. Are there any DIY tips to troubleshoot OBDII code P077D GMC before seeking professional help?
- You can start by checking the sensor and its wiring for visible damage, ensuring proper connections, and clearing the code to see if it reappears after driving. If the issue persists, it's best to consult a mechanic.
8. What steps should I take if OBDII code P077D GMC keeps coming back after repair attempts?
- If the code keeps reappearing after repair attempts, it may indicate an intermittent issue or a deeper underlying problem. In such cases, it is advisable to seek professional diagnostic assistance.
9. Can a faulty transmission output speed sensor cause other transmission issues besides triggering OBDII code P077D GMC?
- Yes, a faulty sensor can cause a range of transmission issues, including rough shifting, delayed engagement, and even complete transmission failure if not addressed promptly.
10. Is it safe to continue driving my vehicle with OBDII code P077D GMC if the transmission seems to be operating normally?
- While the transmission may seem to be operating normally, it's important to address the underlying issue causing the code to prevent potential transmission damage in the future. It is recommended to have the problem diagnosed and repaired as soon as possible.
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