AutoCodes – GMC – P1838 2014 GMC Sierra

P1838 2014 GMC Sierra Code - Internal Mode Switch 'A' 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: P1838 2014 GMC Sierra indicates Internal Mode Switch 'A' 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 141

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 P1838 2014 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 A signal circuit voltage is greater than 2.38 V, for 1.75 s.

OBDII Code P1838 2014 GMC Sierra - Internal Mode Switch 'A' Circuit High Voltage - AutoCodes.com — P1838 2014 GMC Sierra Code - Internal Mode Switch 'A' Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1838 2014 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 P1838 2014 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 P1838 2014 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 P1838 2014 GMC Sierra code?

Need more information on how to fix the P1838 2014 GMC Sierra code? Get Access to Factory Service Manuals

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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 P1838 2014 GMC Sierra Code

1. What are the common symptoms of OBDII code P1838 in a 2014 GMC Sierra?

Common symptoms include issues with shifting gears, hesitation during acceleration, and illuminated warning lights on the dashboard.

2. What does the OBDII code P1838 'Internal Mode Switch 'A' Circuit High Voltage' mean for a 2014 GMC Sierra?

This code indicates that there is a high voltage condition detected in the internal mode switch 'A' circuit of the vehicle.

3. What are the possible causes of OBDII code P1838 in a 2014 GMC Sierra?

Potential causes include a faulty internal mode switch, damaged wiring or connectors in the circuit, or issues with the transmission control module.

4. How can I diagnose the OBDII code P1838 in my 2014 GMC Sierra?

Diagnosis typically involves using a scan tool to read the code, checking the internal mode switch for proper operation, and inspecting the circuit for any visible damage.

5. Can I continue driving my 2014 GMC Sierra with OBDII code P1838?

It is not recommended to drive the vehicle with this code present, as it can lead to further transmission problems and potential safety issues.

6. How can I repair OBDII code P1838 in my 2014 GMC Sierra?

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

7. Is it possible to reset the OBDII code P1838 in a 2014 GMC Sierra without fixing the underlying issue?

While you can clear the code with a scan tool, it will likely reappear if the root cause of the problem is not addressed.

8. How much does it cost to repair OBDII code P1838 in a 2014 GMC Sierra?

The cost of repair can vary depending on the specific cause of the code and the labor rates of the repair facility. It is recommended to get a professional diagnosis for an accurate estimate.

9. Will OBDII code P1838 cause my 2014 GMC Sierra to fail an emissions test?

Yes, having this code stored in the vehicle's computer can result in a failed emissions test, as it indicates an issue with the transmission system.

10. How long does it take to fix OBDII code P1838 in a 2014 GMC Sierra?

The repair time can vary depending on the exact cause of the code and the availability of parts. It is best to consult with a mechanic for a more accurate timeframe.