AutoCodes – Chevrolet – P1838 2018 Chevrolet Silverado

P1838 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado 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 261

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 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado - Internal Mode Switch 'A' Circuit High Voltage - AutoCodes.com — P1838 2018 Chevrolet Silverado Code - Internal Mode Switch 'A' Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1838 2018 Chevrolet Silverado?

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 2018 Chevrolet Silverado?

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 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado code?

Need more information on how to fix the P1838 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado Code

1. What are the common symptoms of OBDII code P1838 in a 2018 Chevrolet Silverado?

- Common symptoms include issues with shifting gears, hesitation or jerking during acceleration, and the Check Engine Light illuminating on the dashboard.

2. What does the OBDII code P1838 'Internal Mode Switch A Circuit High Voltage' indicate in a 2018 Chevrolet Silverado?

- This code indicates that the internal mode switch circuit A is detecting a high voltage condition, which can impact the transmission's operation.

3. What are the possible causes of OBDII code P1838 in a 2018 Chevrolet Silverado?

- Possible causes include a faulty internal mode switch, damaged wiring or connectors in the circuit, low transmission fluid levels, or issues with the transmission control module.

4. How can I diagnose the OBDII code P1838 in my 2018 Chevrolet Silverado?

- Diagnosing this code typically involves using a scan tool to retrieve the fault codes, checking the internal mode switch for proper operation, inspecting the wiring and connectors for damage, and testing the transmission fluid level.

5. Can I continue driving my 2018 Chevrolet Silverado with OBDII code P1838?

- It is not recommended to continue driving the vehicle with this code present, as it can lead to transmission issues and potentially cause further damage. It is advisable to address the problem promptly.

6. How can I repair OBDII code P1838 in my 2018 Chevrolet Silverado?

- Repair options may include replacing the internal mode switch, repairing or replacing damaged wiring or connectors, ensuring the transmission fluid levels are adequate, and addressing any issues with the transmission control module.

7. Will resetting the Check Engine Light resolve OBDII code P1838 in my 2018 Chevrolet Silverado?

- Simply resetting the Check Engine Light will not fix the underlying issue causing the code. It is important to diagnose and repair the root cause of the problem to prevent it from recurring.

8. Is OBDII code P1838 a common issue in 2018 Chevrolet Silverado vehicles?

- While it may not be extremely common, some 2018 Chevrolet Silverado owners have reported experiencing this code related to internal mode switch circuit issues.

9. Can a DIY enthusiast fix OBDII code P1838 in a 2018 Chevrolet Silverado?

- Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to address this code by following repair procedures outlined in the vehicle's service manual or seeking assistance from automotive forums.

10. How much should I expect to pay for repairing OBDII code P1838 in my 2018 Chevrolet Silverado?

- The cost of repairs can vary depending on the exact cause of the issue and whether you choose to address it yourself or take it to a professional mechanic. It is advisable to obtain quotes from local repair shops for an accurate estimate.