AutoCodes – GMC – P0990 2015 GMC Sierra

P0990 2015 GMC Sierra Code - Transmission Fluid Pressure Switch 5 Circuit High Voltage

Quick Answer

The Transmission Fluid Pressure (TFP) switch 5 is part of the Transmission Control Solenoid Valve Assembly, which has no serviceable parts. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly. 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: P0990 2015 GMC Sierra indicates Transmission Fluid Pressure Switch 5 Circuit High Voltage.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly.
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 197

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 Mar 25, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0990 2015 GMC Sierra Description

The Transmission Fluid Pressure (TFP) switch 5 is part of the Transmission Control Solenoid Valve Assembly, which has no serviceable parts. The Transmission Control Module (TCM) supplies a signal circuit to the TFP switch 5. The TFP switch 5 has an internal case ground. TFP switch 5 is normally closed or LOW. When oil pressure is present at the TFP switch 5, the switch is open or HIGH. The normally high-pressure control (PC) solenoid 3 controls pressure to the R1/4-5-6 clutch regular valve. The TCM monitors the TFP switch 5 signal circuit to determine the position of the R1/4-5-6 clutch regulator valve. When the low and reverse clutch and 4-5-6 clutch are commanded OFF, pressure is present on the TFP switch 5. When the low and reverse clutch or the 4-5-6 clutch is commanded ON, the R1/4-5-6 clutch regulator valve moves, and pressure to the TFP switch 5 is exhausted through the R1/4-5-6 clutch regulator valve. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that the TFP switch 5 signal voltage remains HIGH after the 4-5-6 clutch transitions from a LOW pressure state to a HIGH pressure state. The TCM counts each incident. The DTC sets when 15 counts are accumulated.

OBDII Code P0990 2015 GMC Sierra - Transmission Fluid Pressure Switch 5 Circuit High Voltage - AutoCodes.com — P0990 2015 GMC Sierra Code - Transmission Fluid Pressure Switch 5 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0990 2015 GMC Sierra?

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

How to Fix the DTC P0990 2015 GMC Sierra?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0990 2015 GMC Sierra 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 P0990 2015 GMC Sierra code?

Need more information on how to fix the P0990 2015 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 P0990 2015 GMC Sierra Code

1. What does the OBDII code P0990 mean on a 2015 GMC Sierra?

P0990 indicates a high voltage issue in the Transmission Fluid Pressure (TFP) Switch 5 Circuit, which monitors hydraulic pressure in the transmission for proper gear shifting.

2. What are the common symptoms of the P0990 code in a 2015 GMC Sierra?

Common symptoms include harsh or erratic shifting, the transmission stuck in a single gear, reduced engine performance, and an illuminated check engine light.

3. What causes the P0990 code to appear on a 2015 GMC Sierra?

Potential causes include a faulty TFP switch, damaged wiring or connectors in the TFP circuit, a malfunctioning transmission control module (TCM), or low or contaminated transmission fluid.

4. Can I drive my 2015 GMC Sierra with a P0990 code?

It is not recommended to drive with this code as it may cause further transmission damage or unsafe driving conditions due to erratic shifting.

5. How do I diagnose the P0990 code on a 2015 GMC Sierra?

Diagnosis involves checking the TFP switch and circuit for damage, testing the wiring for continuity, inspecting the transmission fluid level and condition, and scanning the TCM for additional codes.

6. How is the P0990 code repaired on a 2015 GMC Sierra?

Repairs may include replacing the TFP switch, repairing or replacing damaged wiring or connectors, flushing and refilling transmission fluid, or reprogramming or replacing the TCM.

7. How much does it cost to fix the P0990 code on a 2015 GMC Sierra?

Repair costs vary but can range from $150 to $500, depending on whether the switch, wiring, or TCM needs replacement and if professional labor is required.

8. Can low transmission fluid cause the P0990 code in a 2015 GMC Sierra?

Yes, low or contaminated transmission fluid can cause incorrect pressure readings, leading to the P0990 code.

9. Does the P0990 code mean the transmission is failing?

Not necessarily. While it could indicate a serious issue, itâ€™s often related to a specific electrical or hydraulic problem that can be repaired without replacing the entire transmission.

10. Will clearing the P0990 code fix the issue on a 2015 GMC Sierra?

Clearing the code may temporarily turn off the check engine light, but the underlying issue must be addressed to prevent the code from returning.