AutoCodes – GMC – P0873 2018 GMC Sierra

P0873 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 3 Circuit High Voltage

Quick Answer

The transmission fluid pressure switch, also known as the pressure switch manifold, is a multiple switch assembly made up of 3 normally open pressure switches and 1 normally closed pressure switch. 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: P0873 2018 GMC Sierra indicates Transmission Fluid Pressure Switch 3 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 254

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 Aug 02, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0873 2018 GMC Sierra Description

The transmission fluid pressure switch, also known as the pressure switch manifold, is a multiple switch assembly made up of 3 normally open pressure switches and 1 normally closed pressure switch. Pressure switch 1 monitors shift valve 1 positioning, pressure switch 2 monitors shift valve 2 positioning, pressure switch 3 monitors shift valve 3 positioning, and pressure switch 4 monitors the position of the manual selector valve. The TCM provides a signal circuit to each of the pressure switches. The TCM constantly monitors the circuits to determine the position of the shift valves. The position of shift valves 1, 2, and 3 is controlled by 3 normally closed shift solenoids. When energized, shift solenoid 1 directs fluid pressure to shift valve 1, shift solenoid 2 directs fluid pressure to shift valve 2, and shift solenoid 3 directs fluid pressure to shift valve 3, which strokes the shift valves. When a shift valve is stroked, an exhaust passage is blocked and fluid pressure increases, closing the normally open pressure switch. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that transmission fluid pressure switch 3 signal circuit is High when shift solenoid 3 is commanded ON for 1 s.

OBDII Code P0873 2018 GMC Sierra - Transmission Fluid Pressure Switch 3 Circuit High Voltage - AutoCodes.com — P0873 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 3 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0873 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
Faulty Transmission Control Module (TCM)

How to Fix the DTC P0873 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 P0873 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.

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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 P0873 2018 GMC Sierra Code

1. What does the OBDII code P0873 mean on a 2018 GMC Sierra?

P0873 indicates that the Transmission Fluid Pressure Switch 3 Circuit is experiencing high voltage, which typically points to an issue with the pressure switch or its associated wiring.

2. What are the common symptoms of code P0873 in a 2018 GMC Sierra?

Symptoms may include erratic or harsh shifting, transmission slipping, the transmission being stuck in one gear, or the illumination of the check engine light.

3. What causes the P0873 code to appear on a 2018 GMC Sierra?

Common causes include a faulty transmission fluid pressure switch, damaged or corroded wiring or connectors in the circuit, low transmission fluid levels, or an internal transmission issue.

4. Can driving with a P0873 code damage my 2018 GMC Sierra?

Yes, driving with this code can potentially cause further damage to the transmission if the issue is not addressed promptly, especially if the transmission is slipping or shifting improperly.

5. How do you diagnose the P0873 code on a 2018 GMC Sierra?

Diagnosis involves scanning the vehicle with an OBDII scanner, inspecting the wiring and connectors for damage, testing the transmission fluid pressure switch, and checking the transmission fluid level and condition.

6. What repairs can fix the P0873 code on a 2018 GMC Sierra?

Repairs may include replacing the transmission fluid pressure switch, repairing or replacing damaged wiring or connectors, replenishing or flushing the transmission fluid, or addressing internal transmission issues.

7. Is low transmission fluid a possible cause of the P0873 code?

Yes, low or degraded transmission fluid can lead to improper pressure readings, which may trigger the P0873 code.

8. How much does it cost to fix the P0873 code on a 2018 GMC Sierra?

Repair costs can vary widely, with pressure switch replacement typically costing $100â€“$300 and more extensive transmission repairs costing significantly more.

9. Can a faulty transmission control module (TCM) cause the P0873 code?

While less common, a malfunctioning TCM can contribute to this code if it fails to interpret pressure switch signals correctly.

10. How can I prevent the P0873 code from recurring on my 2018 GMC Sierra?

Regularly maintain your transmission by checking fluid levels, using the recommended transmission fluid, and addressing wiring or connector issues promptly to prevent circuit malfunctions.