Engine-Codes.com
Engine-Codes – GMC – P1841 2018 GMC Sierra

P1841 2018 GMC Sierra Code - Internal Mode Switch 'S' Circuit High Voltage

Quick Answer

The P1841 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates an issue with the Internal Mode Switch 'S' Circuit High Voltage. Common causes include Faulty Internal Mode Switch sensor, Damaged wiring or connectors in the 'S' circuit, Corrosion or poor connections in the transmission control module. 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
P1841 2018 GMC Sierra indicates Internal Mode Switch 'S' Circuit High Voltage.
Common causes
Common causes include Faulty Internal Mode Switch sensor, Damaged wiring or connectors in the 'S' circuit, Corrosion or poor connections in the transmission control module.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 14, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P1841 2018 GMC Sierra Description

The P1841 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates an issue with the Internal Mode Switch 'S' Circuit High Voltage. The Internal Mode Switch (IMS) is a component of the transmission system that helps the vehicle's computer determine the current gear selection. In this case, the 'S' circuit is reporting a voltage higher than normal, which can lead to various performance issues.

OBDII Code P1841 2018 GMC Sierra - Internal Mode Switch 'S' Circuit High Voltage
P1841 2018 GMC Sierra Code - Internal Mode Switch 'S' Circuit High Voltage

Common Causes of P1841 2018 GMC Sierra

  1. Faulty Internal Mode Switch sensor
  2. Damaged wiring or connectors in the 'S' circuit
  3. Corrosion or poor connections in the transmission control module
  4. Issues with the transmission fluid level or quality
  5. Electrical issues within the transmission system

Symptoms of P1841 2018 GMC Sierra

  1. Harsh shifting between gears
  2. Delayed or erratic gear changes
  3. Transmission slipping
  4. Inability to shift into certain gears
  5. Illumination of the check engine light

How to Fix P1841 2018 GMC Sierra

  1. Begin by conducting a thorough diagnostic scan to confirm the P1841 code and pinpoint the exact cause of the high voltage in the 'S' circuit.
  2. Inspect the Internal Mode Switch sensor and its wiring for any signs of damage or corrosion. Replace the sensor if necessary.
  3. Check the connectors and wiring in the 'S' circuit for any loose connections or breaks. Repair or replace as needed.
  4. Test the transmission control module for proper functionality and address any issues found.
  5. Clear the DTC and perform a test drive to ensure the transmission is shifting correctly and the code does not return.

Cost to Fix P1841 2018 GMC Sierra

The typical repair costs for addressing the Internal Mode Switch 'S' Circuit High Voltage issue can vary depending on the specific cause and the extent of the repairs needed. On average, this repair can range from $200 to $500, including parts and labor. It is important to note that diagnostic time and labor rates at auto repair shops can vary, so it is recommended to obtain quotes from multiple sources to ensure a competitive price.

Need more information about the P1841 2018 GMC Sierra code?

Need more information on how to fix the P1841 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1841 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P1841 2018 GMC Sierra Code

1. What are common symptoms of OBDII code P1841 in a 2018 GMC Sierra?

- Common symptoms include issues with shifting gears, the transmission not engaging properly, and the vehicle going into limp mode.

2. What causes the Internal Mode Switch 'S' Circuit High Voltage code in a 2018 GMC Sierra?

- The code P1841 is typically triggered by a faulty internal mode switch or wiring issues related to the switch.

3. How can I diagnose the Internal Mode Switch issue in my 2018 GMC Sierra?

- You can diagnose the internal mode switch by inspecting the wiring harness, checking for loose connections, and using a multimeter to test the switch's voltage output.

4. Can a DIYer repair OBDII code P1841 in a 2018 GMC Sierra?

- While some DIYers may be able to address this issue by replacing the internal mode switch or repairing wiring, it is recommended to consult a professional mechanic for accurate diagnosis and repair.

5. Are there any temporary fixes for the Internal Mode Switch 'S' Circuit High Voltage code?

- Resetting the vehicle's ECU by disconnecting the battery for a few minutes may temporarily clear the code, but the underlying issue should still be addressed to avoid further problems.

6. Will driving with OBDII code P1841 harm my 2018 GMC Sierra?

- Continuously driving with this code may lead to further transmission issues or failures, so it's best to address the problem as soon as possible to prevent damage.

7. How much does it cost to repair OBDII code P1841 in a 2018 GMC Sierra?

- The cost of repairing this code can vary depending on the specific issue causing it, but it may range from a couple of hundred dollars for parts and labor to over a thousand for more extensive repairs.

8. Can a bad battery cause the Internal Mode Switch 'S' Circuit High Voltage code?

- While a bad battery can potentially cause electrical issues in a vehicle, OBDII code P1841 is more commonly related to problems with the internal mode switch or its circuitry.

9. Is it safe to drive my 2018 GMC Sierra with the Internal Mode Switch 'S' Circuit High Voltage code illuminated?

- It is generally not recommended to drive the vehicle with this code active, as it can affect the transmission's performance and potentially lead to safety issues on the road.

10. How long does it take to repair OBDII code P1841 in a 2018 GMC Sierra?

- The repair time for this code can vary depending on the exact cause of the issue and the availability of parts, but it may take a few hours to a full day for a mechanic to diagnose and fix the problem.

Discuss the causes and fixes for P1841 2018 GMC Sierra OBDII Code

Submit a New Comment

Code P1841 2018 GMC Sierra comments

No comments found for this page.