AutoCodes – GMC – P0748 GMC

P0748 GMC Code - Pressure Control Solenoid Circuit Electrical

Quick Answer

The Pressure Control (PC) solenoid valve is an electronic device that regulates transmission line pressure based on the current flow through its coil winding. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Pressure Control Solenoid. 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: P0748 GMC indicates Pressure Control Solenoid Circuit Electrical.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Pressure Control Solenoid.
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 8,446

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 Jan 29, 2019

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0748 GMC Description

The Pressure Control (PC) solenoid valve is an electronic device that regulates transmission line pressure based on the current flow through its coil winding. The magnetic field produced by the coil moves the solenoid's internal valve which varies pressure to the pressure regulator valve. The Powertrain Control Module (PCM) controls the PC solenoid valve by applying a varying amount of amperage to the solenoid. The applied amperage can vary from 0.1 to 1.1 amps. Low amperage (0.1 amp) indicates high line pressure. High amperage (1.1 amps) indicates low line pressure. The duty cycle of the PC solenoid valve is expressed as a percentage of energized ON time. Zero percent indicates zero ON time (non-energized) or no current flow. Approximately 60% at idle indicates maximum ON time (energized) or high current flow. The PCM determines the appropriate line pressure for a given load by comparing the throttle position (TP) voltage, the engine speed and other inputs.

OBDII Code P0748 GMC - Pressure Control Solenoid Circuit Electrical - AutoCodes.com — P0748 GMC Code - Pressure Control Solenoid Circuit Electrical

What does this mean?

What are the Possible Causes of the DTC P0748 GMC?

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

How to Fix the DTC P0748 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 is 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 removing 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 P0748 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.

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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 P0748 GMC Code

1. What are the common symptoms of OBDII code P0748 GMC (Pressure Control Solenoid Circuit Electrical)?

- Common symptoms of this code include harsh shifting, transmission slipping, and decreased fuel efficiency.

2. What are the possible causes of OBDII code P0748 GMC?

- The code P0748 GMC can be triggered by issues such as a faulty pressure control solenoid, damaged wiring or connectors, low transmission fluid, or a defective transmission control module.

3. How can I diagnose the cause of OBDII code P0748 GMC?

- To diagnose the cause of this code, you can use a scan tool to check for other related trouble codes, inspect the transmission fluid level and condition, and perform a visual inspection of the wiring and connectors.

4. Can I drive my vehicle with OBDII code P0748 GMC?

- It is not recommended to drive your vehicle with OBDII code P0748 GMC as it can lead to further damage to the transmission and other components. It is advised to have the issue diagnosed and repaired as soon as possible.

5. How can I repair OBDII code P0748 GMC?

- Repairing this code may involve replacing the pressure control solenoid, repairing or replacing damaged wiring or connectors, ensuring the transmission fluid is at the correct level, and resetting the trouble codes.

6. How much does it cost to repair OBDII code P0748 GMC?

- The cost of repairing OBDII code P0748 GMC can vary depending on the underlying cause of the issue, the extent of the repairs needed, and the labor rates of the repair shop. It is recommended to obtain quotes from different mechanics for an accurate estimate.

7. Can a DIY enthusiast fix OBDII code P0748 GMC at home?

- While some DIY enthusiasts may have the skills to address OBDII code P0748 GMC at home, it is a complex issue that may require specialized tools and expertise. It is recommended to consult a professional mechanic for proper diagnosis and repair.

8. Is OBDII code P0748 GMC a common issue in GMC vehicles?

- OBDII code P0748 GMC (Pressure Control Solenoid Circuit Electrical) is a relatively common issue in GMC vehicles, especially in models equipped with automatic transmissions.

9. How long does it typically take to repair OBDII code P0748 GMC?

- The repair time for OBDII code P0748 GMC can vary depending on the specific cause of the issue, the availability of parts, and the workload of the repair shop. In general, it may take a few hours to a full day to diagnose and repair the problem.

10. What is the role of the pressure control solenoid in the transmission system related to OBDII code P0748 GMC?

- The pressure control solenoid is responsible for regulating the hydraulic pressure in the transmission system. When the circuit related to this solenoid is experiencing electrical issues, it can trigger OBDII code P0748 GMC and lead to transmission performance issues.