AutoCodes – Generic – B3873:04

B3873:04 Code - Front Washer Relay Circuit Open

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: B3873:04 indicates Front Washer Relay Circuit Open.
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.

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Code Popularity 283

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
Comments
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Code B3873:04 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. The Diagnostic Trouble Code (DTC) will be set when the BCM detects an open or high resistance in the windshield washer pump relay control circuit

OBDII Code B3873:04 - Front Washer Relay Circuit Open - AutoCodes.com — B3873:04 Code - Front Washer Relay Circuit Open

What does this mean?

What are the Possible Causes of the DTC B3873:04?

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 B3873:04?

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 B3873:04 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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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.