AutoCodes – GMC – P0746 GMC

P0746 GMC Code - Transmission Control Solenoid Valve 1 Stuck Off

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: P0746 GMC indicates Transmission Control Solenoid Valve 1 Stuck Off.
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 6,928

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 30, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0746 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 P0746 GMC - Transmission Control Solenoid Valve 1 Stuck Off - AutoCodes.com — P0746 GMC Code - Transmission Control Solenoid Valve 1 Stuck Off

What does this mean?

What are the Possible Causes of the DTC P0746 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 P0746 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 P0746 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 P0746 GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

P0746 2014 GMC Sierra — Transmission Control Solenoid Valve 1 Stuck Off
P0746 2015 GMC Sierra — Transmission Control Solenoid Valve 1 Stuck Off
P0746 2016 GMC Sierra — Transmission Control Solenoid Valve 1 Stuck Off
P0746 2017 GMC Sierra — Transmission Control Solenoid Valve 1 Stuck Off
P0746 2018 GMC Sierra — Transmission Control Solenoid Valve 1 Stuck Off

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?

Youâ€™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 vehicleâ€™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.