AutoCodes – GMC – P0990 2017 GMC Sierra

P0990 2017 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 2017 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 221

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 2017 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 2017 GMC Sierra - Transmission Fluid Pressure Switch 5 Circuit High Voltage - AutoCodes.com — P0990 2017 GMC Sierra Code - Transmission Fluid Pressure Switch 5 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0990 2017 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 2017 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 2017 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 2017 GMC Sierra 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 2017 GMC Sierra Code

1. What does the OBDII code P0990 mean on a 2017 GMC Sierra?

P0990 indicates a "Transmission Fluid Pressure Switch 5 Circuit High Voltage," meaning the powertrain control module (PCM) has detected an abnormal voltage reading in the circuit associated with the transmission fluid pressure switch 5.

2. What are the symptoms of code P0990 on a 2017 GMC Sierra?

Common symptoms include harsh or delayed shifting, the transmission stuck in one gear (limp mode), the check engine light illuminated, and potentially reduced fuel efficiency.

3. What causes the P0990 code to appear on a 2017 GMC Sierra?

Possible causes include a faulty transmission fluid pressure switch, damaged or corroded wiring or connectors in the circuit, a malfunctioning PCM, or low or contaminated transmission fluid.

4. Can low transmission fluid cause a P0990 code on a 2017 GMC Sierra?

Yes, low or contaminated transmission fluid can lead to improper pressure readings, which may trigger the P0990 code.

5. How do you diagnose the P0990 code on a 2017 GMC Sierra?

Diagnosis involves scanning for additional trouble codes, inspecting the transmission fluid for proper level and condition, checking the wiring and connectors in the pressure switch circuit, and testing the pressure switch itself.

6. Is it safe to drive a 2017 GMC Sierra with the P0990 code?

Driving with the P0990 code is not recommended as it can lead to further transmission damage or unsafe driving conditions due to shifting issues.

7. How is the P0990 code fixed on a 2017 GMC Sierra?

Repairs may include replacing the faulty transmission fluid pressure switch, repairing or replacing damaged wiring/connectors, flushing and refilling the transmission fluid, or reprogramming or replacing the PCM if needed.

8. How much does it cost to repair the P0990 code on a 2017 GMC Sierra?

The cost depends on the root cause but typically ranges from $150 to $500 for parts and labor, with the pressure switch replacement being on the lower end and PCM replacement on the higher end.

9. Can a faulty PCM cause the P0990 code on a 2017 GMC Sierra?

Yes, a malfunctioning PCM can misinterpret voltage readings from the pressure switch circuit and trigger the P0990 code.

10. How can I prevent the P0990 code from recurring on my 2017 GMC Sierra?

Regular maintenance, such as ensuring proper transmission fluid levels and condition, inspecting wiring and connectors for damage, and addressing transmission issues promptly, can help prevent this code.