AutoCodes – Chevrolet – P1839 Chevrolet

P1839 Chevrolet Code - Internal Mode Switch 'C' Circuit Low Voltage

Quick Answer

The internal mode switch indicates the Transmission Control Module (TCM) which gear position the vehicle operator has selected. Common causes include Faulty Transmission Internal Mode Switch, Transmission Internal Mode Switch harness is open or shorted, Transmission Internal Mode Switch circuit poor electrical connection. 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: P1839 Chevrolet indicates Internal Mode Switch 'C' Circuit Low Voltage.
Common causes: Common causes include Faulty Transmission Internal Mode Switch, Transmission Internal Mode Switch harness is open or shorted, Transmission Internal Mode Switch circuit poor electrical connection.
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 3,808

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 23, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1839 Chevrolet Description

The internal mode switch indicates the Transmission Control Module (TCM) which gear position the vehicle operator has selected. The internal mode switch consists of 5 separate hall effect switches. Each hall effect switch is supplied with a 9 V reference circuit and a signal circuit from the TCM. Each signal circuit for each gear selector position will have either a voltage reading of 0.70–0.96 V indicating On or 1.68–2.38 V indicating Off. The voltage values on each internal mode switch circuit will change and are dependent on the position of the gear selector. The state of each internal mode switch A/B/C/P/S signal circuit is displayed on the scan tool. The Diagnostic Trouble Code (DTC) will be set when the TCM has detected the internal mode switch C signal circuit voltage is less than 0.7 V, for 1.75 s.

OBDII Code P1839 Chevrolet - Internal Mode Switch 'C' Circuit Low Voltage - AutoCodes.com — P1839 Chevrolet Code - Internal Mode Switch 'C' Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1839 Chevrolet?

Faulty Transmission Internal Mode Switch
Transmission Internal Mode Switch harness is open or shorted
Transmission Internal Mode Switch circuit poor electrical connection
Faulty Transmission Control Module (TCM)

How to Fix the DTC P1839 Chevrolet?

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 P1839 Chevrolet 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 P1839 Chevrolet code?

Need more information on how to fix the P1839 Chevrolet code? Get Access to Factory Service Manuals

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Get the P1839 Chevrolet code diagnosed by a professional: Find a repair shop in your area

Information for Specific Chevrolet Models

P1839 2014 Chevrolet Silverado — Internal Mode Switch 'C' Circuit Low Voltage
P1839 2015 Chevrolet Silverado — Internal Mode Switch 'C' Circuit Low Voltage
P1839 2016 Chevrolet Silverado — Internal Mode Switch 'C' Circuit Low Voltage
P1839 2017 Chevrolet Silverado — Internal Mode Switch 'C' Circuit Low Voltage
P1839 2018 Chevrolet Silverado — Internal Mode Switch 'C' Circuit Low 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 P1839 Chevrolet Code

1. What are the common symptoms of OBDII code P1839 in a Chevrolet related to the Internal Mode Switch 'C' Circuit Low Voltage?

- Common symptoms include issues with shifting gears, poor acceleration, and possible illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P1839 in a Chevrolet indicating Internal Mode Switch 'C' Circuit Low Voltage?

- The code P1839 can be caused by a faulty internal mode switch, damaged wiring or connectors, or issues with the transmission control module.

3. How serious is OBDII code P1839 related to the Internal Mode Switch 'C' Circuit Low Voltage in a Chevrolet?

- While the vehicle may still be operable with this code, it is important to address it promptly to avoid potential transmission problems and ensure safe driving conditions.

4. Can I continue driving my Chevrolet with OBDII code P1839 indicating Internal Mode Switch 'C' Circuit Low Voltage?

- It is not recommended to ignore this code and continue driving, as it can lead to more severe transmission issues if left unattended.

5. How can I diagnose OBDII code P1839 in a Chevrolet for the Internal Mode Switch 'C' Circuit Low Voltage?

- Diagnosing this code may involve using a diagnostic scanner to retrieve the code, inspecting the internal mode switch, checking for damaged wiring, and testing the transmission control module.

6. How can I repair OBDII code P1839 related to Internal Mode Switch 'C' Circuit Low Voltage in my Chevrolet?

- Repair options may include replacing the internal mode switch, repairing damaged wiring or connectors, or reprogramming the transmission control module.

7. Are there any DIY tips for addressing OBDII code P1839 in a Chevrolet with Internal Mode Switch 'C' Circuit Low Voltage?

- DIY enthusiasts can start by checking the wiring and connectors for any visible damage, ensuring they are securely connected, and then proceeding with component replacement if necessary.

8. How much does it typically cost to repair OBDII code P1839 for Internal Mode Switch 'C' Circuit Low Voltage in a Chevrolet?

- Repair costs can vary depending on the extent of the issue, but they may range from a few hundred to over a thousand dollars, including parts and labor.

9. Can resetting the OBDII system clear the P1839 code related to Internal Mode Switch 'C' Circuit Low Voltage in a Chevrolet?

- While clearing the code may temporarily turn off the Check Engine Light, it is essential to address the underlying issue causing the code to prevent future problems.

10. Is it necessary to visit a professional mechanic for OBDII code P1839 in a Chevrolet indicating Internal Mode Switch 'C' Circuit Low Voltage?

- It is recommended to consult a qualified mechanic or technician with experience in diagnosing and repairing transmission-related issues to properly address the code P1839 in your Chevrolet.