Engine-Codes.com
Engine-Codes – GMC – B1840 2018 GMC Sierra

B1840 2018 GMC Sierra Code - Driver Seat Lumbar Up Switch Circuit

Quick Answer

The B1840 diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the driver seat lumbar up switch circuit. Common causes include Faulty wiring harness connected to the driver seat lumbar up switch, Malfunctioning driver seat lumbar up switch, Issue with the seat 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
B1840 2018 GMC Sierra indicates Driver Seat Lumbar Up Switch Circuit.
Common causes
Common causes include Faulty wiring harness connected to the driver seat lumbar up switch, Malfunctioning driver seat lumbar up switch, Issue with the seat 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 16, 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 B1840 2018 GMC Sierra Description

The B1840 diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the driver seat lumbar up switch circuit. This code indicates that there is a malfunction in the circuit responsible for controlling the driver seat's lumbar support adjustment in the upward direction. The lumbar support feature is designed to provide additional lower back support and comfort for the driver, and a malfunction in this circuit can lead to an inability to adjust the lumbar support in the upward direction.

OBDII Code B1840 2018 GMC Sierra - Driver Seat Lumbar Up Switch Circuit
B1840 2018 GMC Sierra Code - Driver Seat Lumbar Up Switch Circuit

Common Causes of B1840 2018 GMC Sierra

  1. Faulty wiring harness connected to the driver seat lumbar up switch.
  2. Malfunctioning driver seat lumbar up switch.
  3. Issue with the seat control module.
  4. Poor electrical connection or corrosion in the circuit.

Symptoms of B1840 2018 GMC Sierra

  1. Inability to adjust the driver seat lumbar support in the upward direction.
  2. Malfunctioning or unresponsive lumbar up switch on the driver seat.
  3. Erratic or inconsistent movement of the driver seat lumbar support.
  4. Illumination of the airbag warning light on the instrument panel.

How to Fix B1840 2018 GMC Sierra

  1. Begin by conducting a thorough visual inspection of the wiring harness connected to the driver seat lumbar up switch to check for any visible damage or loose connections.
  2. Test the driver seat lumbar up switch using a multimeter to determine if it is functioning properly.
  3. If the switch is faulty, replace it with a new one following the manufacturer's instructions.
  4. Check the seat control module for any signs of damage or malfunction, and replace if necessary.
  5. Ensure all electrical connections in the circuit are secure and free of corrosion.

Cost to Fix B1840 2018 GMC Sierra

The typical repair costs for addressing the B1840 code on a 2018 GMC Sierra could range from $150 to $400, depending on the specific cause of the issue and the cost of replacement parts. It's important to note that diagnosis time and labor rates at auto repair shops can vary, with hourly rates typically ranging between $80 and $150. Factors such as location, vehicle make and model, and engine type can also impact the final repair costs. For a more accurate estimate, it's recommended to consult with local auto repair shops.

What does this mean?

Tech Notes for B1840 2018 GMC Sierra









User Submitted Video

Need more information about the B1840 2018 GMC Sierra code?

Need more information on how to fix the B1840 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B1840 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 B1840 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code B1840 in a 2018 GMC Sierra related to the Driver Seat Lumbar Up Switch Circuit?

- The common symptoms include the driver seat lumbar up switch not functioning properly or not responding when pressed.

2. What are the possible causes of OBDII code B1840 in a 2018 GMC Sierra?

- The possible causes include a faulty driver seat lumbar up switch, wiring issues in the circuit, or a malfunctioning control module.

3. How can I diagnose the issue related to OBDII code B1840 in my 2018 GMC Sierra?

- You can start by checking the wiring connections to the driver seat lumbar up switch, testing the switch for continuity, and using a diagnostic scanner to retrieve more specific information.

4. Can I repair OBDII code B1840 in my 2018 GMC Sierra myself?

- Depending on your skills and experience with automotive repairs, you may be able to repair the issue yourself by replacing the faulty switch, repairing any damaged wiring, or resetting the control module.

5. Is it safe to continue driving my 2018 GMC Sierra with OBDII code B1840 present?

- It is generally not recommended to ignore OBDII codes, as they indicate potential issues that could affect the vehicle's performance or safety. It's best to address the problem as soon as possible.

6. How much does it typically cost to repair OBDII code B1840 in a 2018 GMC Sierra?

- The cost of repairs can vary depending on the exact cause of the issue, the parts needed, and whether you choose to do the repairs yourself or take the vehicle to a professional mechanic.

7. Are there any temporary solutions to address OBDII code B1840 in my 2018 GMC Sierra?

- While temporary solutions may vary depending on the specific issue, you can try checking and securing any loose wiring connections or fuses related to the driver seat lumbar up switch.

8. Will resetting the vehicle's computer clear OBDII code B1840 in my 2018 GMC Sierra?

- Resetting the computer may temporarily clear the code, but if the underlying issue is not addressed, the code is likely to reappear once the problem is detected again.

9. Can extreme temperatures or humidity affect the driver seat lumbar up switch circuit in a 2018 GMC Sierra?

- Extreme temperatures or humidity can potentially cause electrical components to malfunction, so it's important to keep the vehicle's interior environment stable to avoid such issues.

10. How can I prevent OBDII code B1840 from recurring in my 2018 GMC Sierra after repairs?

- To prevent the code from recurring, ensure that any repairs are done properly, regularly inspect the wiring and components related to the driver seat lumbar up switch, and address any issues promptly.

Discuss the causes and fixes for B1840 2018 GMC Sierra OBDII Code

Submit a New Comment

Code B1840 2018 GMC Sierra comments

No comments found for this page.