AutoCodes – Buick – P0989 Buick

P0989 Buick 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 Buick 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 2,185

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 25, 2024

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0989 Buick 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 Buick - Transmission Fluid Pressure Switch 5 Circuit Low Voltage - AutoCodes.com — P0989 Buick Code - Transmission Fluid Pressure Switch 5 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P0989 Buick?

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 Buick?

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

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0989 Buick 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 Buick code?

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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 Buick Code

1. What are the common symptoms of OBDII code P0989 in a Buick related to the Transmission Fluid Pressure Switch 5 Circuit Low Voltage?

- Common symptoms may include harsh shifting, transmission slipping, decreased fuel efficiency, and the illumination of the check engine light.

2. What are the possible causes of OBDII code P0989 in a Buick?

- The code can be triggered by issues such as a faulty transmission fluid pressure switch, low transmission fluid levels, a damaged wiring harness, or a problem with the transmission control module.

3. How serious is OBDII code P0989 in a Buick?

- While the vehicle may still be drivable with this code, it is important to address it promptly to prevent potential damage to the transmission system.

4. How can I diagnose OBDII code P0989 in a Buick?

- Diagnosis typically involves using an OBDII scanner to retrieve the code, conducting a visual inspection of the transmission fluid pressure switch and related components, and testing the switch's electrical circuit.

5. How can I repair OBDII code P0989 in a Buick?

- Repair options may include replacing the faulty transmission fluid pressure switch, fixing any damaged wiring, ensuring proper transmission fluid levels, and resetting the check engine light after the issue is resolved.

6. Can I drive my Buick with OBDII code P0989?

- It is generally not recommended to drive the vehicle with this code present, as it can lead to further transmission problems if left unaddressed.

7. How much does it cost to fix OBDII code P0989 in a Buick?

- The cost of repairs can vary depending on the exact cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

8. Can OBDII code P0989 be triggered intermittently in a Buick?

- Yes, it is possible for the code to be triggered intermittently, especially if the issue is related to a loose connection or a sporadic fault in the system.

9. Is it safe to clear the OBDII code P0989 in a Buick with a diagnostic tool?

- Clearing the code with a diagnostic tool is safe after the issue has been diagnosed and fixed. It is important to ensure that the root cause of the problem has been addressed before clearing the code.

10. What should I do if OBDII code P0989 persists in my Buick after repairs?

- If the code persists after repairs, it is recommended to recheck the repairs made, conduct further diagnostics, or seek assistance from a qualified mechanic to pinpoint and resolve the issue.