AutoCodes – GMC – P1841 GMC

P1841 GMC Code - Internal Mode Switch 'S' Circuit High 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: P1841 GMC indicates Internal Mode Switch 'S' Circuit High 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 1,452

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 P1841 GMC 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 S signal circuit voltage is greater than 2.38 V, for 1.75 s.

OBDII Code P1841 GMC - Internal Mode Switch 'S' Circuit High Voltage - AutoCodes.com — P1841 GMC Code - Internal Mode Switch 'S' Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1841 GMC?

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 P1841 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 P1841 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 P1841 GMC code?

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

Need Help with the Code?

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Information for Specific GMC Models

P1841 2014 GMC Sierra — Internal Mode Switch 'S' Circuit High Voltage
P1841 2015 GMC Sierra — Internal Mode Switch 'S' Circuit High Voltage
P1841 2016 GMC Sierra — Internal Mode Switch 'S' Circuit High Voltage
P1841 2017 GMC Sierra — Internal Mode Switch 'S' Circuit High Voltage
P1841 2018 GMC Sierra — Internal Mode Switch 'S' 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 P1841 GMC Code

1. What are the common symptoms of OBDII code P1841 GMC?

The common symptoms of OBDII code P1841 GMC include issues with gear shifting, transmission slipping, and the inability to engage certain gears.

2. What can cause the Internal Mode Switch 'S' Circuit High Voltage error code to appear?

The error code P1841 GMC typically appears due to a faulty internal mode switch, damaged wiring in the circuit, or a malfunctioning transmission control module.

3. How serious is the Internal Mode Switch 'S' Circuit High Voltage error code?

This error code should be addressed promptly as it can lead to transmission issues and potential safety hazards on the road.

4. How can I diagnose the cause of OBDII code P1841 GMC?

Diagnosing the cause of this error code involves conducting a thorough inspection of the internal mode switch, checking the wiring for any damage, and testing the transmission control module for proper functioning.

5. Can I continue driving my vehicle with the P1841 GMC error code?

It is not recommended to continue driving your vehicle with the P1841 error code, as it can lead to further damage to the transmission system.

6. How can I repair the Internal Mode Switch 'S' Circuit High Voltage issue?

Repairing the P1841 GMC code may involve replacing the internal mode switch, repairing any damaged wiring, or reprogramming the transmission control module.

7. Are there any DIY tips for fixing the P1841 GMC error code?

While some basic troubleshooting steps can be done by DIY enthusiasts, it is recommended to seek professional help for a proper diagnosis and repair of the P1841 code.

8. How much does it typically cost to fix the Internal Mode Switch 'S' Circuit High Voltage error?

The cost of fixing the P1841 GMC error can vary depending on the extent of the damage, parts needed for replacement, and labor costs. It is advisable to get a quote from a trusted mechanic.

9. Can resetting the error code make it go away permanently?

Resetting the error code may temporarily clear the code, but if the underlying issue causing the P1841 GMC error is not addressed, it is likely to reappear.

10. How long does it take to repair the P1841 GMC error?

The repair time for the P1841 GMC error can vary based on the complexity of the issue, availability of parts, and the mechanic's expertise. It is recommended to consult with a professional for an accurate estimate.