AutoCodes – GMC – B3873 2018 GMC Sierra

B3873 2018 GMC Sierra Code - Front Washer Relay Circuit

Quick Answer

The windshield washer function is controlled by the Body Control Module (BCM). Common causes include Faulty Front Washer Relay, Front Washer Relay harness is open or shorted, Front Washer Relay 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: B3873 2018 GMC Sierra indicates Front Washer Relay Circuit.
Common causes: Common causes include Faulty Front Washer Relay, Front Washer Relay harness is open or shorted, Front Washer Relay 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 245

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 Jun 14, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code B3873 2018 GMC Sierra Description

The windshield washer function is controlled by the Body Control Module (BCM). When the washer switch is pressed, low reference is applied through the switch contacts and the signal circuit to the body control module indicating the wash request. The body control module then applies voltage through the control circuit to the coil side of the windshield washer pump relay energizing the relay. With the relay energized, battery voltage from the fuse is applied through the switch contacts of the relay and the control circuit to the windshield washer fluid pump.

OBDII Code B3873 2018 GMC Sierra - Front Washer Relay Circuit - AutoCodes.com — B3873 2018 GMC Sierra Code - Front Washer Relay Circuit

What does this mean?

What are the Possible Causes of the DTC B3873 2018 GMC Sierra?

Faulty Front Washer Relay
Front Washer Relay harness is open or shorted
Front Washer Relay circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3873 2018 GMC Sierra?

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

B3873:01 Front Washer Relay Circuit Short to Battery
B3873:02 Front Washer Relay Circuit Short to Ground
B3873:04 Front Washer Relay Circuit Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3873 2018 GMC Sierra 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 B3873 2018 GMC Sierra code?

Need more information on how to fix the B3873 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3873 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 B3873 2018 GMC Sierra Code

1. What does the OBDII code B3873 mean on a 2018 GMC Sierra?

B3873 indicates an issue with the Front Washer Relay Circuit, which controls the operation of the front windshield washer system.

2. What are the common symptoms of code B3873 on a 2018 GMC Sierra?

Symptoms may include the windshield washer not spraying, intermittent washer operation, or the washer system failing to activate when needed.

3. What causes the B3873 code to appear on a 2018 GMC Sierra?

Common causes include a faulty front washer relay, damaged wiring or connectors in the washer circuit, or issues with the body control module (BCM).

4. How can I diagnose the B3873 code on my GMC Sierra?

Start by checking the washer relay for proper operation, inspect the wiring and connectors for damage or corrosion, and use a scan tool to verify BCM functionality.

5. Can a blown fuse cause the B3873 code on a 2018 GMC Sierra?

Yes, a blown fuse related to the windshield washer system can interrupt the circuit and trigger this code.

6. How do I fix the B3873 code on my 2018 GMC Sierra?

Repairs may include replacing a faulty washer relay, repairing or replacing damaged wiring, cleaning corroded connectors, or reprogramming the BCM if necessary.

7. Is it safe to drive with the B3873 code active on my 2018 GMC Sierra?

Yes, but driving without a functional windshield washer system can reduce visibility in poor weather, which may compromise safety.

8. How much does it cost to repair the B3873 code on a 2018 GMC Sierra?

The cost can vary, but replacing a washer relay typically costs between $50 and $150, while wiring repairs or BCM reprogramming may cost more.

9. Can I reset the B3873 code without repairing anything on my GMC Sierra?

You can clear the code with a scan tool, but if the underlying issue isnâ€™t fixed, the code will likely return.

10. What tools are needed to troubleshoot the B3873 code on a 2018 GMC Sierra?

Youâ€™ll need a scan tool to read and clear codes, a multimeter to test wiring and relay functionality, and potentially a wiring diagram for the washer circuit.