AutoCodes – Generic – B3811

B3811 Code - Rear Washer Relay Circuit

Quick Answer

The Body Control Module (BCM) controls the rear washer based on an input from the rear wiper switch, which is part of the turn signal/multifunction switch. Common causes include Faulty Rear Window Washer Pump, Rear Window Washer Pump harness is open or shorted, Rear Window Washer Pump 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: B3811 indicates Rear Washer Relay Circuit.
Common causes: Common causes include Faulty Rear Window Washer Pump, Rear Window Washer Pump harness is open or shorted, Rear Window Washer Pump 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 3,759

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 B3811 Description

The Body Control Module (BCM) controls the rear washer based on an input from the rear wiper switch, which is part of the turn signal/multifunction switch. The BCM monitors the rear wiper switch through separate signal circuits and a ground circuit. The rear wiper switch uses a resistor ladder to determine low speed, intermittent, and rear washer operation. The BCM monitors applies and monitors voltage on the rear wiper switch signal circuit. When the rear wiper switch is placed in the low speed, intermittent, or rear washer position, the voltage is pulled down through a different resistor in the resistor ladder, reducing the voltage seen at the BCM. The BCM will respond by commanding the specific rear wiper function.
The rear window washer pump is controlled by the BCM controls through the rear washer pump relay. When the rear wash switch is pressed, ignition voltage from the BCM is applied to the rear washer relay control circuit. The rear washer relay control circuit is used to energize the relay coil and close the rear washer pump control circuit to B+.

OBDII Code B3811 - Rear Washer Relay Circuit - AutoCodes.com — B3811 Code - Rear Washer Relay Circuit

What does this mean?

What are the Possible Causes of the DTC B3811?

Faulty Rear Window Washer Pump
Rear Window Washer Pump harness is open or shorted
Rear Window Washer Pump circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3811?

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 B3811 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 B3811 code?

Need more information on how to fix the B3811 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3811 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B3811 Buick — Rear Washer Relay Circuit
B3811 Cadillac — Rear Washer Relay Circuit
B3811 Chevrolet — Rear Washer Relay Circuit
B3811 GMC — Rear Washer Relay 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 B3811 Code

1. What are common symptoms of OBDII code B3811 (Rear Washer Relay Circuit)?

- Common symptoms include the rear washer not functioning when activated, no washer fluid spraying onto the rear windshield, or intermittent operation of the rear washer.

2. What could cause OBDII code B3811 to trigger?

- The code B3811 may be triggered due to a faulty rear washer relay, a damaged wiring harness related to the rear washer system, or a malfunctioning rear washer switch.

3. How can I diagnose the cause of OBDII code B3811 (Rear Washer Relay Circuit)?

- To diagnose the issue, you can start by checking the rear washer relay for proper operation, inspecting the wiring for any damage or loose connections, and testing the rear washer switch for functionality.

4. Can a blown fuse cause OBDII code B3811 to appear?

- Yes, a blown fuse in the rear washer circuit can also trigger OBDII code B3811. It is recommended to check and replace any blown fuses as part of the diagnostic process.

5. What is the typical repair for OBDII code B3811 (Rear Washer Relay Circuit)?

- The typical repair involves replacing the faulty rear washer relay, repairing any damaged wiring in the circuit, or addressing any issues with the rear washer switch as needed.

6. Are there any DIY tips for fixing OBDII code B3811?

- DIY tips for addressing OBDII code B3811 include checking and replacing any blown fuses, visually inspecting the wiring for damage, and testing the rear washer relay and switch with a multimeter.

7. Can OBDII code B3811 be safely ignored?

- Ignoring OBDII code B3811 is not recommended, as it indicates a problem with the rear washer relay circuit that can affect the proper functioning of the rear washer system.

8. Is it possible to reset OBDII code B3811 without repairing the issue?

- While clearing the code temporarily may be possible with an OBDII scanner, it is essential to address the underlying cause of B3811 to prevent the issue from reoccurring.

9. How critical is it to fix OBDII code B3811 promptly?

- It is important to address OBDII code B3811 promptly to ensure the rear washer system operates correctly, especially for visibility and safety while driving in adverse weather conditions.

10. Can a professional mechanic help diagnose and repair OBDII code B3811?

- Yes, a professional mechanic can efficiently diagnose and repair OBDII code B3811 by utilizing specialized tools, expertise, and experience in automotive electrical systems.