AutoCodes – Generic – B3801

B3801 Code - Passenger Compartment Lamp Request Circuit

Quick Answer

The Body Control Module (BCM) monitors the courtesy lamp switch signal circuit in order to determine when the courtesy/dome lamps should be illuminated. Common causes include Faulty Headlamp Switch, Headlamp Switch harness is open or shorted, Headlamp 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: B3801 indicates Passenger Compartment Lamp Request Circuit.
Common causes: Common causes include Faulty Headlamp Switch, Headlamp Switch harness is open or shorted, Headlamp 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 2,507

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 17, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3801 Description

The Body Control Module (BCM) monitors the courtesy lamp switch signal circuit in order to determine when the courtesy/dome lamps should be illuminated. When the BCM senses that the courtesy lamp switch signal circuit is grounded when the switch is activated, the BCM will illuminate the courtesy/dome lamps. The Diagnostic Trouble Code (DTC) sets when the BCM instrument panel dimmer switch reference voltage must be between 4.5-5.5 volts.

OBDII Code B3801 - Passenger Compartment Lamp Request Circuit - AutoCodes.com — B3801 Code - Passenger Compartment Lamp Request Circuit

What does this mean?

What are the Possible Causes of the DTC B3801?

Faulty Headlamp Switch
Headlamp Switch harness is open or shorted
Headlamp Switch circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3801?

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 B3801 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 B3801 code?

Need more information on how to fix the B3801 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3801 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B3801 Buick — Passenger Compartment Lamp Request Circuit
B3801 Cadillac — Passenger Compartment Lamp Request Circuit
B3801 Chevrolet — Passenger Compartment Lamp Request Circuit
B3801 GMC — Passenger Compartment Lamp Request 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 B3801 Code

1. What are the common symptoms of OBDII code B3801 (Passenger Compartment Lamp Request Circuit)?

- The common symptoms include the passenger compartment lamp failing to illuminate, dimming or flickering light, or the lamp staying on constantly.

2. What are the possible causes of OBDII code B3801?

- The code B3801 can be caused by a faulty passenger compartment lamp, a damaged wiring harness, a blown fuse, or a malfunctioning body control module.

3. How can I diagnose OBDII code B3801?

- Diagnosing OBDII code B3801 involves checking the passenger compartment lamp for functionality, inspecting the wiring for any damage, testing the fuse for continuity, and using a scan tool to check the body control module for faults.

4. Can I repair OBDII code B3801 myself?

- If you have the necessary tools and knowledge, you may be able to repair OBDII code B3801 yourself by replacing the faulty passenger compartment lamp, repairing any damaged wiring, replacing a blown fuse, or addressing issues with the body control module.

5. Is it safe to continue driving with OBDII code B3801 present?

- While the code B3801 is related to the passenger compartment lamp and may not affect the drivability of the vehicle, it is recommended to address the issue promptly to ensure proper interior lighting for visibility and safety.

6. How much does it cost to fix OBDII code B3801?

- The cost of fixing OBDII code B3801 can vary depending on the specific cause of the issue. It may range from a simple fuse replacement costing a few dollars to more complex repairs involving the body control module, which can be more expensive.

7. Can OBDII code B3801 cause any other problems in the vehicle?

- While OBDII code B3801 is primarily related to the passenger compartment lamp, ignoring the issue may lead to reduced visibility inside the vehicle, especially at night. It is important to address the problem to maintain safety and convenience.

8. Are there any common troubleshooting steps for OBDII code B3801?

- Common troubleshooting steps for OBDII code B3801 include checking the lamp bulb, inspecting the wiring connections, testing the fuse, and resetting the body control module if needed.

9. Will OBDII code B3801 cause the check engine light to illuminate?

- OBDII code B3801 is related to the interior lighting system and may not directly cause the check engine light to illuminate. However, it may trigger other warning lights if the issue affects the overall electrical system.

10. How long does it typically take to repair OBDII code B3801?

- The repair time for OBDII code B3801 can vary depending on the cause of the issue and the complexity of the repairs needed. Simple fixes like changing a bulb or fuse can be done quickly, while more extensive repairs may take longer.