AutoCodes – GMC – P0843 GMC

P0843 GMC Code - Transmission Fluid Pressure Switch 1 Circuit High Voltage

Quick Answer

The Transmission Fluid Pressure (TFP) switch 1 is part of the 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: P0843 GMC indicates Transmission Fluid Pressure Switch 1 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 716

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 02, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0843 GMC Description

The Transmission Fluid Pressure (TFP) switch 1 is part of the control solenoid valve assembly, which has no serviceable parts. The Transmission Control Module (TCM) supplies a signal circuit to the TFP Switch 1. The TFP Switch 1 has an internal case ground. TFP Switch 1 is normally closed or LOW. When oil pressure is present at the TFP Switch 1, the switch is open or HIGH. The normally high clutch pressure control (PC) solenoid 2 controls pressure to the 3-5 reverse clutch regulator valve. The TCM monitors the TFP switch 1 to determine the position of the 3-5 reverse clutch regulator valve. When the 3-5 reverse clutch is commanded OFF, pressure is present on the TFP switch 1. When the 3-5 reverse clutch is commanded ON, the 3-5 reverse clutch regulator valve moves and pressure to the TFP switch 1 is exhausted through the 3-5 reverse clutch regulator valve. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that the TFP switch 1 signal voltage remains HIGH after the 3-5-R clutch transitions from a LOW pressure state to a HIGH pressure state. The TCM counts each incident. The DTC sets when 35 counts are accumulated.

OBDII Code P0843 GMC - Transmission Fluid Pressure Switch 1 Circuit High Voltage - AutoCodes.com — P0843 GMC Code - Transmission Fluid Pressure Switch 1 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0843 GMC?

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 P0843 GMC?

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 P0843 GMC 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 P0843 GMC code?

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Need Help with the Code?

Get the P0843 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P0843 2014 GMC Sierra — Transmission Fluid Pressure Switch 1 Circuit High Voltage
P0843 2015 GMC Sierra — Transmission Fluid Pressure Switch 1 Circuit High Voltage
P0843 2016 GMC Sierra — Transmission Fluid Pressure Switch 1 Circuit High Voltage
P0843 2017 GMC Sierra — Transmission Fluid Pressure Switch 1 Circuit High Voltage
P0843 2018 GMC Sierra — Transmission Fluid Pressure Switch 1 Circuit High Voltage

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 P0843 GMC Code

1. What are common symptoms of OBDII code P0843 in a GMC vehicle?

- Common symptoms include harsh shifting, transmission slippage, illuminated Check Engine light, and decreased fuel efficiency.

2. What does the OBDII code P0843 GMC indicate?

- The code indicates a high voltage condition in the transmission fluid pressure switch 1 circuit.

3. What are possible causes of OBDII code P0843 in a GMC vehicle?

- Possible causes include a faulty transmission fluid pressure switch, damaged wiring or connectors, low transmission fluid, or a malfunctioning transmission control module.

4. How serious is OBDII code P0843 in a GMC vehicle?

- This code should be addressed promptly as it can lead to transmission issues if left unresolved, potentially causing further damage.

5. Can I continue driving with OBDII code P0843 present in my GMC vehicle?

- It is not recommended to continue driving with this code present, as it can affect the performance and reliability of the transmission.

6. How can OBDII code P0843 in a GMC vehicle be diagnosed?

- Diagnosis involves using a scan tool to read the code, performing a visual inspection of the transmission fluid pressure switch and related components, and conducting electrical tests.

7. What are some repair tips for addressing OBDII code P0843 in a GMC vehicle?

- Repair tips may include replacing the transmission fluid pressure switch, repairing damaged wiring or connectors, checking and topping up transmission fluid, and resetting the fault code.

8. Can I reset the OBDII code P0843 in a GMC vehicle myself?

- Yes, the code can be reset using an OBDII scanner, but it is important to address the underlying issue causing the code to prevent it from reoccurring.

9. How much does it cost to repair OBDII code P0843 in a GMC vehicle?

- The cost of repairs can vary depending on the exact cause of the code, but it may involve parts and labor expenses ranging from $100 to $500 or more.

10. Is OBDII code P0843 a common issue in GMC vehicles?

- While it may not be as common as some other OBDII codes, P0843 can still occur in GMC vehicles, particularly in those with automatic transmissions.