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Engine-Codes – GMC – P0974 2018 GMC Sierra

P0974 2018 GMC Sierra Code - Shift Solenoid Valve 1 Control Circuit High Voltage

Quick Answer

The P0974 diagnostic trouble code (DTC) in a 2018 GMC Sierra indicates a problem with the Shift Solenoid Valve 1 Control Circuit registering a high voltage. Common causes include Faulty shift solenoid valve, Damaged wiring or connectors in the control circuit, Issues with the transmission control module (TCM). 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
P0974 2018 GMC Sierra indicates Shift Solenoid Valve 1 Control Circuit High Voltage.
Common causes
Common causes include Faulty shift solenoid valve, Damaged wiring or connectors in the control circuit, Issues with the transmission control module (TCM).
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 16, 2024
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Code P0974 2018 GMC Sierra Description

The P0974 diagnostic trouble code (DTC) in a 2018 GMC Sierra indicates a problem with the Shift Solenoid Valve 1 Control Circuit registering a high voltage. This solenoid is responsible for controlling the flow of transmission fluid to engage or disengage specific gears in the transmission. When the control circuit detects a voltage higher than the specified range, it can lead to issues with shifting gears smoothly and efficiently.

OBDII Code P0974 2018 GMC Sierra - Shift Solenoid Valve 1 Control Circuit High Voltage
P0974 2018 GMC Sierra Code - Shift Solenoid Valve 1 Control Circuit High Voltage

Common Causes of P0974 2018 GMC Sierra

  1. Faulty shift solenoid valve
  2. Damaged wiring or connectors in the control circuit
  3. Issues with the transmission control module (TCM)
  4. Malfunctioning powertrain control module (PCM)
  5. Low transmission fluid levels

Symptoms of P0974 2018 GMC Sierra

  1. Harsh or delayed shifting
  2. Erratic transmission behavior
  3. Transmission slipping
  4. Illuminated Check Engine Light
  5. Reduced fuel efficiency

How to Fix P0974 2018 GMC Sierra

  1. Diagnose the specific cause of the high voltage in the Shift Solenoid Valve 1 Control Circuit using a scan tool to retrieve the DTC and perform electrical testing.
  2. Inspect the shift solenoid valve, wiring, and connectors for any signs of damage or corrosion. Replace any faulty components.
  3. Test the transmission control module (TCM) and powertrain control module (PCM) for proper operation and reprogram if necessary.
  4. Clear the DTC and perform a test drive to ensure the issue has been resolved and the transmission is functioning correctly.
  5. Regularly monitor the transmission system for any further issues to prevent future problems.

Cost to Fix P0974 2018 GMC Sierra

The typical repair costs for addressing a P0974 code in a 2018 GMC Sierra can range from $200 to $500, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that diagnosis time and labor rates at auto repair shops can vary, with hourly rates typically ranging between $80 and $150. Factors such as location, vehicle make and model, and engine type can also influence the overall repair costs. It is advisable to consult with a trusted mechanic or repair shop to obtain a more accurate estimate based on your specific circumstances.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0974 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P0974 in a 2018 GMC Sierra?

- Common symptoms include harsh shifting, delayed or erratic gear shifts, transmission slipping, and decreased fuel efficiency.

2. What causes the Shift Solenoid Valve 1 Control Circuit High Voltage code (P0974) in a 2018 GMC Sierra?

- The code P0974 is usually triggered by issues such as a faulty shift solenoid, damaged wiring or connectors, low transmission fluid levels, or a defective transmission control module.

3. How can I diagnose the Shift Solenoid Valve 1 Control Circuit High Voltage code (P0974) on my 2018 GMC Sierra?

- Diagnosing P0974 involves conducting a thorough inspection of the shift solenoid, checking the wiring for any damage, testing the transmission fluid level, and using a scan tool to retrieve the trouble codes.

4. Can I continue driving my 2018 GMC Sierra with OBDII code P0974 present?

- It is not recommended to drive with the P0974 code present as it can lead to further damage to the transmission and potentially result in costly repairs. It's best to address the issue promptly.

5. How can I repair OBDII code P0974 in my 2018 GMC Sierra?

- Repairing the P0974 code may involve replacing the shift solenoid valve, repairing or replacing damaged wiring or connectors, ensuring proper transmission fluid levels, and resetting the trouble codes using a scan tool.

6. Is it possible to reset the OBDII code P0974 in a 2018 GMC Sierra without fixing the underlying issue?

- While you can reset the trouble codes using a scan tool, it's important to address the root cause of the P0974 code to prevent it from recurring and potentially causing further damage to the transmission.

7. How much does it typically cost to repair OBDII code P0974 in a 2018 GMC Sierra?

- The cost of repairing the P0974 code can vary depending on the underlying issue, the labor rates in your area, and whether you tackle the repair yourself or take it to a professional mechanic. Costs may range from a few hundred to over a thousand dollars.

8. Can a DIY enthusiast fix OBDII code P0974 in a 2018 GMC Sierra?

- While some DIY enthusiasts may have the skills and tools to address the P0974 code, it's recommended to have a professional diagnose and repair transmission-related issues due to their complexity and importance in vehicle operation.

9. What other related OBDII codes might be triggered along with P0974 in a 2018 GMC Sierra?

- Related codes that might be triggered alongside P0974 include P0973 (Shift Solenoid Valve 1 Control Circuit Low), P0975 (Shift Solenoid Valve 1 Control Circuit Range/Performance), and P0976 (Shift Solenoid Valve 1 Control Circuit Low).

10. How can I prevent OBDII code P0974 from occurring in my 2018 GMC Sierra in the future?

- To prevent the P0974 code from occurring, it's essential to maintain your vehicle's transmission system regularly, address any transmission fluid leaks promptly, and ensure the electrical connections related to the shift solenoid are in good condition.

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