AutoCodes – Generic – B051B:04

B051B:04 Code - Right Side Assist Step Motor Control Circuit Open Circuit

Quick Answer

The Assist Step Control (ASC) Module controls the running board actuators to extend or retract the running boards. Common causes include Faulty Right Side Assist Step Motor, Right Side Assist Step Motor harness is open or shorted, Right Side Assist Step Motor circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B051B:04 indicates Right Side Assist Step Motor Control Circuit Open Circuit.
Common causes: Common causes include Faulty Right Side Assist Step Motor, Right Side Assist Step Motor harness is open or shorted, Right Side Assist Step Motor circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 558

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 13, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B051B:04 Description

The Assist Step Control (ASC) Module controls the running board actuators to extend or retract the running boards. Each actuator consists of an electric motor and a potentiometer. The module supplies a low reference and 10-volt reference source voltage to the potentiometer. The ASC control module monitors the voltage drop across the potentiometer on the position signal circuit. When the actuator shaft rotates, the voltage on the position signal circuit changes. The ASC control module supplies the actuator motor with a 12-volt control circuit and a ground control circuit. The ASC module controls the direction of the actuator by changing the polarity of the control circuits. The Diagnostic Trouble Code (DTC) will be set when a motor control circuit is open.

OBDII Code B051B:04 - Right Side Assist Step Motor Control Circuit Open Circuit - AutoCodes.com — B051B:04 Code - Right Side Assist Step Motor Control Circuit Open Circuit

What does this mean?

What are the Possible Causes of the DTC B051B:04?

Faulty Right Side Assist Step Motor
Right Side Assist Step Motor harness is open or shorted
Right Side Assist Step Motor circuit poor electrical connection
Faulty Assist Step Control (ASC) Module

How to Fix the DTC B051B: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

B051B:0B Right Side Assist Step Motor Control Circuit Current Above Threshold
B051B:01 Right Side Assist Step Motor Control Circuit Short to Battery
B051B:02 Right Side Assist Step Motor Control Circuit Short to Ground
B051B:04 Right Side Assist Step Motor Control Circuit Open Circuit

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B051B: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.

Frequently Asked Questions about B051B:04 Code

1. What does the OBDII code B051B:04 mean?

The code B051B:04 indicates an open circuit in the right side assist step motor control circuit, meaning there is a disruption in the electrical connection to the motor controlling the right assist step.

2. What are common symptoms of the B051B:04 code?

Symptoms include the right side assist step not deploying or retracting, warning messages or lights on the dashboard, and an audible clicking or no movement from the assist step motor.

3. What causes the B051B:04 code to appear?

Common causes include damaged or corroded wiring, a faulty assist step motor, a disconnected connector, or a malfunctioning control module.

4. Can I still drive my vehicle with the B051B:04 code?

Yes, the vehicle can still be driven. However, the right side assist step may not function properly, which could be inconvenient or pose a safety risk when entering or exiting the vehicle.

5. How do I diagnose the B051B:04 code?

Start by inspecting the wiring and connectors for damage or corrosion. Use a multimeter to check for continuity in the circuit and test the functionality of the right assist step motor.

6. How do I fix the B051B:04 code?

Repairs may include repairing or replacing damaged wiring, reconnecting loose connectors, replacing the right assist step motor, or resetting the control module if needed.

7. How much does it cost to repair the B051B:04 code?

The cost varies depending on the cause, but replacing a motor can cost $200â€“$500, while wiring repairs typically cost less. Labor charges depend on the shop.

8. Can I clear the B051B:04 code without fixing the problem?

Clearing the code without addressing the issue will only temporarily remove it. The code will likely return if the underlying problem isn't resolved.

9. Is the B051B:04 code specific to certain vehicle makes or models?

This code is more commonly found in vehicles equipped with power-deployable side assist steps, such as certain trucks or SUVs.

10. How can I prevent the B051B:04 code from occurring?

Regularly inspect the assist step mechanism for dirt or debris, ensure wiring and connectors are clean and secure, and address any electrical issues promptly.