AutoCodes – GMC – P0989 2018 GMC Sierra

P0989 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 5 Circuit Low 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: P0989 2018 GMC Sierra indicates Transmission Fluid Pressure Switch 5 Circuit Low 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 208

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 P0989 2018 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 LOW after the 4-5-6 clutch transitions from a HIGH pressure state to a LOW pressure state. The TCM counts each incident. The DTC sets when 18 counts are accumulated.

OBDII Code P0989 2018 GMC Sierra - Transmission Fluid Pressure Switch 5 Circuit Low Voltage - AutoCodes.com — P0989 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 5 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P0989 2018 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 P0989 2018 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 P0989 2018 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 P0989 2018 GMC Sierra code?

Need more information on how to fix the P0989 2018 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 P0989 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P0989 in a 2018 GMC Sierra?

The common symptoms include harsh shifting, transmission slippage, delayed engagement, and illuminated Check Engine Light.

2. What does the OBDII code P0989 indicate in a 2018 GMC Sierra?

The code P0989 indicates a low voltage condition in Transmission Fluid Pressure Switch 5 Circuit of the vehicle's transmission system.

3. What are the possible causes of OBDII code P0989 in a 2018 GMC Sierra?

Possible causes include a faulty transmission fluid pressure switch, damaged wiring or connectors in the circuit, low transmission fluid levels, or a malfunctioning transmission control module.

4. How can I diagnose the OBDII code P0989 in my 2018 GMC Sierra?

Diagnosis involves using a scan tool to retrieve the code, checking the transmission fluid level and condition, inspecting the wiring and connectors related to Transmission Fluid Pressure Switch 5, and testing the switch for proper operation.

5. Can I continue driving my 2018 GMC Sierra with OBDII code P0989?

It is not recommended to continue driving with this code present, as it can lead to further transmission damage and potential safety issues. It's best to address the issue promptly.

6. How can I repair OBDII code P0989 in my 2018 GMC Sierra?

Repair options include replacing the faulty transmission fluid pressure switch, repairing or replacing damaged wiring or connectors, ensuring proper transmission fluid levels, and resetting the trouble code with a scan tool.

7. Is it necessary to visit a mechanic for OBDII code P0989 in a 2018 GMC Sierra?

While some DIY enthusiasts may be able to address this issue themselves, consulting a professional mechanic is recommended for accurate diagnosis and proper repair to prevent further transmission damage.

8. Can a low voltage condition in Transmission Fluid Pressure Switch 5 Circuit cause other transmission issues?

Yes, a low voltage condition can affect the proper operation of the transmission, leading to shifting problems, decreased performance, and potential long-term damage if not addressed promptly.

9. How much does it typically cost to repair OBDII code P0989 in a 2018 GMC Sierra?

The cost of repair can vary depending on the exact cause of the issue, but it may involve parts and labor expenses ranging from $200 to $500, or more if additional transmission repairs are needed.

10. How can I prevent OBDII code P0989 from occurring in the future in my 2018 GMC Sierra?

Regular maintenance of the transmission system, including checking fluid levels, inspecting wiring connections, and addressing any issues promptly, can help prevent the recurrence of this trouble code.