AutoCodes – Chevrolet – B1840 Chevrolet

B1840 Chevrolet Code - Driver Seat Lumbar Up Switch Circuit

Quick Answer

The Seat Memory Control Module supplies a reference voltage to each signal circuit of the Driver Seat Adjuster Switch. Common causes include Faulty Driver Seat Adjuster Switch, Driver Seat Adjuster Switch harness is open or shorted, Driver Seat Adjuster 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: B1840 Chevrolet indicates Driver Seat Lumbar Up Switch Circuit.
Common causes: Common causes include Faulty Driver Seat Adjuster Switch, Driver Seat Adjuster Switch harness is open or shorted, Driver Seat Adjuster 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 291

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Apr 24, 2023

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code B1840 Chevrolet Description

The Seat Memory Control Module supplies a reference voltage to each signal circuit of the Driver Seat Adjuster Switch. When the power seat or lumbar switches are pressed, the appropriate signal circuit from the Seat Memory Control Module is pulled low through the switch contacts indicating the power seat command. The Seat Memory Control Module then commands the driver seat or lumbar to move in response to the switch signals. The Diagnostic Trouble Code (DTC) will be set when there is a short to ground on a switch signal circuit.

OBDII Code B1840 Chevrolet - Driver Seat Lumbar Up Switch Circuit - AutoCodes.com — B1840 Chevrolet Code - Driver Seat Lumbar Up Switch Circuit

What does this mean?

What are the Possible Causes of the DTC B1840 Chevrolet?

Faulty Driver Seat Adjuster Switch
Driver Seat Adjuster Switch harness is open or shorted
Driver Seat Adjuster Switch circuit poor electrical connection
Faulty Seat Memory Control Module

How to Fix the DTC B1840 Chevrolet?

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 does this mean?

Code Tech Notes

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B1840 Chevrolet 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.

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Information for Specific Chevrolet Models

B1840 2014 Chevrolet Silverado — Driver Seat Lumbar Up Switch Circuit
B1840 2015 Chevrolet Silverado — Driver Seat Lumbar Up Switch Circuit
B1840 2016 Chevrolet Silverado — Driver Seat Lumbar Up Switch Circuit
B1840 2017 Chevrolet Silverado — Driver Seat Lumbar Up Switch Circuit
B1840 2018 Chevrolet Silverado — Driver Seat Lumbar Up Switch Circuit

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 Chevrolet Code

1. What does the OBDII code B1840 mean on a Chevrolet?

The B1840 code indicates an issue with the driver seat lumbar up switch circuit, such as a fault in the wiring, switch, or related component.

2. What are the symptoms of the B1840 code on a Chevrolet?

Symptoms may include the lumbar support not adjusting upward, unresponsive lumbar controls, or intermittent functioning of the driver seat lumbar switch.

3. What causes the B1840 code to trigger?

Common causes include a faulty lumbar up switch, damaged wiring or connectors, or a malfunction in the seat control module.

4. How do I diagnose the B1840 code on my Chevrolet?

Begin by inspecting the lumbar switch and its wiring for damage, test the circuit with a multimeter, and check the seat control module for faults.

5. Can I still drive with the B1840 code active?

Yes, you can drive with this code active, but the lumbar support adjustment feature may not work, potentially reducing seat comfort.

6. How do I fix the B1840 code on a Chevrolet?

Repairs may involve replacing the lumbar up switch, repairing damaged wiring, reconnecting loose connectors, or recalibrating the seat control module.

7. How much does it cost to repair the B1840 code?

Repair costs can vary but typically range from $50 to $300 depending on whether the issue is with the switch, wiring, or seat control module.

8. Can a blown fuse cause the B1840 code?

While unlikely, it's possible if the fuse related to the seat controls is blown, so checking the fuse box is a good step in diagnosis.

9. Will clearing the B1840 code with a scanner fix the problem?

Clearing the code will reset the system temporarily, but the issue will likely return unless the underlying problem is resolved.

10. Do I need to replace the entire seat to fix the B1840 code?

No, the entire seat doesn't need replacement. The issue is typically resolved by repairing or replacing the specific faulty component in the lumbar up switch circuit.