AutoCodes – GMC – P0877 2018 GMC Sierra

P0877 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 4 Circuit Low Voltage

Quick Answer

The Transmission Fluid Pressure (TFP) switch 4 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: P0877 2018 GMC Sierra indicates Transmission Fluid Pressure Switch 4 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 219

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 Aug 03, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0877 2018 GMC Sierra Description

The Transmission Fluid Pressure (TFP) switch 4 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 4. The TFP switch 4 has an internal case ground. TFP switch 4 is normally closed or LOW. When oil pressure is present at the TFP switch 4, the switch is open or HIGH. The normal LOW pressure control solenoid 5 controls pressure to the 1-2-3-4 clutch regulator valve. The TCM monitors the TFP switch 4 to determine the position of the 1-2-3-4 clutch regulator valve. When the 1-2-3-4 clutch is commanded OFF, pressure is present on the TFP switch 4. When the 1-2-3-4 clutch is commanded ON, the 1-2-3-4 clutch regulator valve moves and pressure to the TFP switch 4 is exhausted through the 1-2-3-4 clutch regulator valve. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that the TFP switch 4 signal voltage remains LOW after the 1-2-3-4 clutch transitions from a HIGH pressure state to a LOW pressure state. The TCM counts each incident. The DTC sets when 5 counts are accumulated.

OBDII Code P0877 2018 GMC Sierra - Transmission Fluid Pressure Switch 4 Circuit Low Voltage - AutoCodes.com — P0877 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 4 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P0877 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 P0877 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 P0877 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 P0877 2018 GMC Sierra 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 P0877 2018 GMC Sierra Code

1. What does OBDII code P0877 mean on a 2018 GMC Sierra?

P0877 indicates that the Transmission Fluid Pressure Switch 4 circuit is experiencing low voltage, suggesting an electrical or mechanical issue with the pressure switch.

2. What are the symptoms of code P0877 on a 2018 GMC Sierra?

Common symptoms include erratic shifting, the transmission staying in limp mode, delayed gear engagement, and the check engine light being illuminated.

3. What causes code P0877 on 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 an issue with the transmission control module (TCM).

4. Can low transmission fluid cause code P0877?

Yes, low transmission fluid can lead to inadequate pressure, potentially triggering the P0877 code.

5. How do I diagnose code P0877 on my 2018 GMC Sierra?

Start by checking the transmission fluid level and condition, inspecting the wiring and connectors for damage, and testing the transmission fluid pressure switch with a multimeter.

6. Can I drive my 2018 GMC Sierra with code P0877 active?

It is not recommended, as driving with this issue can lead to further damage to the transmission and result in unsafe driving conditions.

7. How do I fix code P0877 on a 2018 GMC Sierra?

Repairs may involve replacing the faulty pressure switch, repairing or replacing damaged wiring, cleaning corroded connectors, or reprogramming/updating the TCM.

8. How much does it cost to repair code P0877 on a 2018 GMC Sierra?

The cost varies depending on the repair, but replacing a transmission fluid pressure switch typically costs $150â€“$300, while wiring repairs may vary based on labor.

9. Can a faulty TCM cause code P0877?

Yes, a malfunctioning TCM can misinterpret or fail to process signals from the pressure switch, potentially triggering the P0877 code.

10. Is a professional mechanic required to fix code P0877?

While some issues like checking fluid levels or inspecting wiring can be done at home, diagnosing and repairing electrical or transmission-related problems often requires professional expertise.