AutoCodes – GMC – B3874 GMC

B3874 GMC Code - Wiper Low Speed Relay Circuit

Quick Answer

The Body Control Module (BCM) controls and monitors the state of the wiper control circuit. Common causes include Faulty Wiper Low Speed Relay, Wiper Low Speed Relay harness is open or shorted, Wiper Low Speed 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: B3874 GMC indicates Wiper Low Speed Relay Circuit.
Common causes: Common causes include Faulty Wiper Low Speed Relay, Wiper Low Speed Relay harness is open or shorted, Wiper Low Speed 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 435

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 23, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3874 GMC Description

The Body Control Module (BCM) controls and monitors the state of the wiper control circuit. When the windshield wiper switch is placed in to a low speed setting, a signal is applied to the BCM. The BCM then applies the battery positive voltage to the coil side of the relay through the relay control circuit. The Diagnostic Trouble Code (DTC) sets when the ignition is in the ON position or the ignition voltage is between 9-16 volts.

OBDII Code B3874 GMC - Wiper Low Speed Relay Circuit - AutoCodes.com — B3874 GMC Code - Wiper Low Speed Relay Circuit

What does this mean?

What are the Possible Causes of the DTC B3874 GMC?

Faulty Wiper Low Speed Relay
Wiper Low Speed Relay harness is open or shorted
Wiper Low Speed Relay circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B3874 GMC?

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 B3874 GMC 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 B3874 GMC code?

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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.

Frequently Asked Questions about B3874 GMC Code

1. What are the common symptoms of OBDII code B3874 GMC (Wiper Low Speed Relay Circuit)?

- Common symptoms include slow or erratic wiper operation, wipers not working at low speed, and intermittent wiper function.

2. What are some possible causes of OBDII code B3874 GMC?

- Possible causes include a faulty wiper low speed relay, damaged wiring or connectors in the wiper circuit, or a malfunctioning wiper motor.

3. How can I diagnose the issue related to OBDII code B3874 GMC?

- You can diagnose the issue by checking the wiper relay, inspecting the wiring and connectors for any damage, and testing the wiper motor for proper operation.

4. What are some repair tips for fixing OBDII code B3874 GMC?

- Repair tips include replacing the wiper low speed relay if faulty, repairing any damaged wiring or connectors, and replacing the wiper motor if necessary.

5. Can I drive my vehicle with OBDII code B3874 GMC present?

- It is not recommended to drive your vehicle with this code present, as it may affect the proper functioning of your wipers, especially during inclement weather.

6. How do I reset OBDII code B3874 GMC after making repairs?

- You can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes to clear the error code.

7. Are there any safety precautions to consider when working on the wiper low speed relay circuit?

- Safety precautions include disconnecting the vehicle's battery before working on the circuit, wearing appropriate protective gear, and following proper repair procedures.

8. Can extreme weather conditions affect the wiper low speed relay circuit and trigger OBDII code B3874 GMC?

- Yes, extreme weather conditions such as heavy rain or snow can put additional strain on the wiper circuit components and contribute to the development of this code.

9. Is it possible to prevent OBDII code B3874 GMC from occurring in the future?

- Regularly inspecting and maintaining the wiper system, keeping the windshield clean, and addressing any wiper issues promptly can help prevent this code from occurring.

10. How long does it typically take to repair OBDII code B3874 GMC?

- The repair time can vary depending on the exact cause of the issue, but in general, it can take anywhere from 30 minutes to a few hours to diagnose and fix the problem.