AutoCodes – GMC – P1841 2017 GMC Sierra

P1841 2017 GMC Sierra 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 2017 GMC Sierra 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 159

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 2017 GMC Sierra 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 2017 GMC Sierra - Internal Mode Switch 'S' Circuit High Voltage - AutoCodes.com — P1841 2017 GMC Sierra Code - Internal Mode Switch 'S' Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1841 2017 GMC Sierra?

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 2017 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 P1841 2017 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.

Need more information about the P1841 2017 GMC Sierra code?

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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 P1841 2017 GMC Sierra Code

1. What does the OBDII code P1841 mean on a 2017 GMC Sierra?

P1841 indicates an issue with the Internal Mode Switch (IMS) 'S' circuit, specifically high voltage being detected by the Powertrain Control Module (PCM).

2. What are the common symptoms of code P1841 in a 2017 GMC Sierra?

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

3. What causes code P1841 to appear on a 2017 GMC Sierra?

Common causes include a faulty internal mode switch, damaged wiring or connectors in the IMS circuit, a malfunctioning transmission control module (TCM), or electrical issues such as short circuits or corrosion.

4. How do I diagnose the P1841 code on my 2017 GMC Sierra?

Start by scanning the vehicle with an OBDII scanner to confirm the code. Then, inspect the IMS wiring and connectors for damage, check the IMS for proper operation, and test the voltage and continuity of the circuit.

5. Can I drive my 2017 GMC Sierra with the P1841 code?

Driving with this code is not recommended, as it may cause further damage to the transmission or lead to unsafe driving conditions due to erratic shifting.

6. How do I fix the P1841 code on my 2017 GMC Sierra?

Repair steps may include replacing the internal mode switch, repairing or replacing damaged wiring, cleaning corroded connectors, or reprogramming the TCM if necessary.

7. How much does it typically cost to repair code P1841 on a 2017 GMC Sierra?

Repair costs vary, but replacing the internal mode switch can range from $200 to $500, including parts and labor. Additional costs may apply for wiring repairs or TCM reprogramming.

8. Can a bad internal mode switch cause other transmission issues?

Yes, a faulty internal mode switch can lead to improper gear selection, delayed shifting, or the transmission being stuck in the wrong gear.

9. How can I prevent code P1841 from reoccurring in my 2017 GMC Sierra?

Ensure regular maintenance of the transmission, inspect wiring and connectors for wear or corrosion, and address any electrical issues promptly to prevent future problems.

10. Is reprogramming the TCM always necessary to fix code P1841?

Not always. Reprogramming the TCM is only required if a software update or corrupted programming is contributing to the issue. Most cases involve physical repairs to the internal mode switch or circuit.