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AutoCodes – GMC – P0747 GMC

P0747 GMC Code - Transmission Control Solenoid Valve 1 Stuck On

Quick Answer

The solenoid actuator controls fluid pressure by moving the clutch 1-2-3-4-5-6 regulator valve that controls the fluid pressure to the 1-2-3-4-5-6 clutch. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve. 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
P0747 GMC indicates Transmission Control Solenoid Valve 1 Stuck On.
Common causes
Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve.
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.
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Code Popularity 9,783
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Jul 30, 2022
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Code P0747 GMC Description

The solenoid actuator controls fluid pressure by moving the clutch 1-2-3-4-5-6 regulator valve that controls the fluid pressure to the 1-2-3-4-5-6 clutch. The Solenoid Valve is an electronic pressure actuator that controls transmission line pressure based on current flow through its coil windings. As current flow is increased, the magnetic field produced by the coil moves the solenoid’s plunger further away from the exhaust port. Opening the exhaust port decreases the output fluid pressure regulated by the solenoid valve, which ultimately decreases line pressure.
OBDII Code P0747 GMC - Transmission Control Solenoid Valve 1 Stuck On - AutoCodes.com
P0747 GMC Code - Transmission Control Solenoid Valve 1 Stuck On
What does this mean?

What are the Possible Causes of the DTC P0747 GMC?

  • Low transmission fluid level
  • Dirty transmission fluid
  • Faulty Transmission Control Solenoid Valve
  • Transmission Control Solenoid Valve harness is open or shorted
  • Transmission Control Solenoid Valve circuit poor electrical connection

How to Fix the DTC P0747 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 does this mean?

Code Tech Notes

When a transmission solenoid has malfunctioned, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is dirty, it's recommended to change the transmission fluid and if possible, remove the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a mechanical transmission failure, and that the transmission will need to be rebuilt or replaced.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0747 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 P0747 GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

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 P0747 GMC Code

1. What does the OBDII code P0747 mean on a GMC vehicle?

P0747 indicates that the Transmission Control Solenoid Valve 1 is stuck in the "on" position, causing improper operation of the transmission.

2. What are the common symptoms of code P0747 in a GMC?

Symptoms may include harsh shifting, transmission slippage, failure to engage certain gears, reduced fuel efficiency, and the Check Engine Light being illuminated.

3. What causes the P0747 code on a GMC?

Common causes include a faulty transmission control solenoid, low or dirty transmission fluid, internal transmission damage, or issues in the wiring or connectors related to the solenoid.

4. Can I drive my GMC with a P0747 code?

Driving with this code is not recommended as it can cause further damage to the transmission and result in unsafe driving conditions.

5. How is code P0747 diagnosed on a GMC?

A technician will use a scan tool to verify the code, inspect the transmission fluid, test the solenoid's electrical circuit, and perform a pressure test if necessary.

6. How do I fix code P0747 on my GMC?

Repairs may include replacing the stuck solenoid, changing the transmission fluid and filter, repairing wiring issues, or addressing internal transmission damage.

7. How much does it cost to repair a P0747 code on a GMC?

The cost varies but can range from $150 to $400 for solenoid replacement, with higher costs if internal transmission repairs are required.

8. Can low transmission fluid cause a P0747 code?

Yes, low or contaminated transmission fluid can cause the solenoid to malfunction and trigger the P0747 code.

9. How can I prevent the P0747 code from occurring on my GMC?

Regular transmission maintenance, such as fluid changes and inspections, can help prevent solenoid issues and avoid this code.

10. Is the P0747 code specific to GMC vehicles?

No, P0747 is a generic OBDII code that can appear on various makes and models, but the specific symptoms and solutions may vary by vehicle.

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