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Engine-Codes – GMC – P0746 GMC

P0746 GMC Code - Transmission Control Solenoid Valve 1 Stuck Off

Quick Answer

The P0746 GMC code indicates that the Transmission Control Solenoid Valve 1 is stuck off. Common causes include Malfunctioning Transmission Control Solenoid Valve 1, Electrical faults in the transmission system, Wiring issues or poor connections. 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
P0746 GMC indicates Transmission Control Solenoid Valve 1 Stuck Off.
Common causes
Common causes include Malfunctioning Transmission Control Solenoid Valve 1, Electrical faults in the transmission system, Wiring issues or poor connections.
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 08, 2024
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Code P0746 GMC Description

The P0746 GMC code indicates that the Transmission Control Solenoid Valve 1 is stuck off. This solenoid valve is a crucial component of the transmission system, responsible for controlling the flow of transmission fluid to engage the appropriate gear ratios. When this solenoid valve is stuck in the off position, it can lead to a variety of issues, affecting the vehicle's performance and drivability.

OBDII Code P0746 GMC - Transmission Control Solenoid Valve 1 Stuck Off
P0746 GMC Code - Transmission Control Solenoid Valve 1 Stuck Off

Common Causes of P0746 GMC

  1. Malfunctioning Transmission Control Solenoid Valve 1
  2. Electrical faults in the transmission system
  3. Wiring issues or poor connections
  4. Problems with the transmission control module
  5. Low transmission fluid levels or dirty fluid

Symptoms of P0746 GMC

  1. Delayed or harsh shifting
  2. Poor acceleration
  3. Reduced fuel efficiency
  4. Slipping gears
  5. Difficulty engaging gears

How to Fix P0746 GMC

  1. Diagnose the issue by using a scan tool to retrieve the trouble codes and inspecting the Transmission Control Solenoid Valve 1 for any visible damage.
  2. Replace the faulty Transmission Control Solenoid Valve 1 with a new one, ensuring proper installation and connection.
  3. Check the wiring and connections for any signs of damage or corrosion, repairing or replacing as necessary.
  4. Inspect the transmission control module for faults or damage, replacing if needed.
  5. Perform a transmission fluid flush and refill if the fluid is low or dirty, ensuring the correct fluid type is used.

Cost to Fix P0746 GMC

The typical repair costs for addressing a P0746 GMC code can range from $200 to $500, including parts and labor. However, the specific diagnosis time and labor rates at auto repair shops can vary significantly based on factors such as location, vehicle make and model, and engine type. It's recommended to check with local shops for a more accurate estimate. Keep in mind that rates may be higher in metropolitan areas or at dealerships, while independent shops often offer more competitive pricing.

What does this mean?

Tech Notes for P0746 GMC

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.

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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 P0746 GMC Code

What does the OBDII code P0746 mean for a GMC vehicle?

P0746 indicates that the Transmission Control Solenoid Valve 1 is stuck off, preventing proper regulation of hydraulic pressure in the transmission.

What are the common symptoms of the P0746 code in a GMC vehicle?

Symptoms may include harsh or delayed shifting, transmission slipping, poor acceleration, reduced fuel efficiency, and the check engine light turning on.

What causes the P0746 code to appear in GMC vehicles?

Common causes include a faulty transmission control solenoid, low transmission fluid, clogged fluid passages, electrical issues like damaged wiring or connectors, or internal transmission problems.

Can driving with the P0746 code damage my GMC vehicle?

Yes, driving with this code can cause further damage to the transmission and lead to costly repairs if not addressed promptly.

How can I diagnose the P0746 code in a GMC vehicle?

Diagnose by checking transmission fluid level and condition, inspecting the wiring and connectors to the solenoid, and using a scan tool to monitor solenoid operation and related transmission parameters.

How do I fix the P0746 code on my GMC vehicle?

Repairs may include replacing the transmission control solenoid, flushing or refilling transmission fluid, repairing damaged wiring, or addressing internal transmission issues if necessary.

What tools are needed to fix the P0746 code in a GMC vehicle?

You’ll need a diagnostic scan tool, basic hand tools, transmission fluid, and potentially specialized tools for accessing or replacing the solenoid inside the transmission.

Is the P0746 code covered under warranty for GMC vehicles?

It depends on your vehicle’s age, mileage, and warranty terms. Transmission-related issues might be covered under the powertrain warranty.

Can a dirty transmission fluid cause the P0746 code?

Yes, dirty or contaminated transmission fluid can lead to clogged passages and solenoid malfunction, contributing to the P0746 code.

How much does it cost to repair the P0746 code on a GMC vehicle?

Repair costs vary widely, ranging from $150-$450 for solenoid replacement to $1,000 or more for internal transmission repairs, depending on the extent of the issue.

Discuss the causes and fixes for P0746 GMC OBDII Code

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