AutoCodes – Generic – B051A:04

B051A:04 Code - Left 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 Left Side Assist Step Motor, Left Side Assist Step Motor harness is open or shorted, Left 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: B051A:04 indicates Left Side Assist Step Motor Control Circuit Open Circuit.
Common causes: Common causes include Faulty Left Side Assist Step Motor, Left Side Assist Step Motor harness is open or shorted, Left 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 839

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 B051A: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 B051A:04 - Left Side Assist Step Motor Control Circuit Open Circuit - AutoCodes.com — B051A:04 Code - Left Side Assist Step Motor Control Circuit Open Circuit

What does this mean?

What are the Possible Causes of the DTC B051A:04?

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

How to Fix the DTC B051A: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

B051A:0B Left Side Assist Step Motor Control Circuit Current Above Threshold
B051A:01 Left Side Assist Step Motor Control Circuit Short to Battery
B051A:02 Left Side Assist Step Motor Control Circuit Short to Ground
B051A:04 Left Side Assist Step Motor Control Circuit Open Circuit

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B051A: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 B051A:04 Code

1. What does the OBDII code B051A:04 mean?

The code B051A:04 indicates an open circuit in the left side assist step motor control circuit, meaning the motor or wiring for the assist step on the driver's side has a malfunction.

2. What are the common symptoms of code B051A:04?

Symptoms include the left side assist step not deploying or retracting, a warning message on the dashboard, or the motor making no noise when activated.

3. What causes the B051A:04 code to appear?

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

4. How can I diagnose the B051A:04 code?

Start by inspecting the wiring and connectors for damage or corrosion, testing the assist step motor for proper operation, and using a multimeter to check continuity in the circuit.

5. Can I still drive my vehicle with the B051A:04 code?

Yes, you can drive with this code, but the left side assist step may not function properly, which could be inconvenient or unsafe in certain situations.

6. How do I fix the B051A:04 code?

Repairs may involve repairing or replacing damaged wiring, cleaning or reconnecting corroded connectors, replacing the faulty assist step motor, or reprogramming the control module if needed.

7. How much does it cost to fix the B051A:04 code?

Repair costs vary depending on the issue, but wiring or connector repairs are typically inexpensive, while replacing the assist step motor or control module could cost several hundred dollars.

8. Can I fix the B051A:04 code myself?

If you have basic automotive repair skills and tools, you may be able to fix wiring or connector issues yourself. However, diagnosing or replacing the motor or control module may require professional assistance.

9. What tools are needed to troubleshoot the B051A:04 code?

Youâ€™ll need a diagnostic scanner, a multimeter for testing circuits, and basic tools for accessing and inspecting the assist step motor and wiring.

10. Will clearing the B051A:04 code solve the problem?

Clearing the code without addressing the underlying issue will not fix the problem, and the code is likely to return until the circuit fault is resolved.