AutoCodes – Generic – U3503

U3503 Code - Control Module Input Power 'A' Circuit Intermittent/Erratic

Quick Answer

The vehicle control modules or sensors monitor the system voltage to verify the system voltage is within the normal operating range. Common causes include Faulty Control Module setting the code, Control Module harness is open or shorted, Control Module 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: U3503 indicates Control Module Input Power 'A' Circuit Intermittent/Erratic.
Common causes: Common causes include Faulty Control Module setting the code, Control Module harness is open or shorted, Control Module 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 1,102

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 18, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U3503 Description

The vehicle control modules or sensors monitor the system voltage to verify the system voltage is within the normal operating range. With the ignition is ON, the Diagnostic Trouble Code (DTC) will set when the control module or sensor detects a system voltage of less than approximately 9 V for approximately 5 s.

OBDII Code U3503 - Control Module Input Power 'A' Circuit Intermittent/Erratic - AutoCodes.com — U3503 Code - Control Module Input Power 'A' Circuit Intermittent/Erratic

What does this mean?

What are the Possible Causes of the DTC U3503?

Faulty Control Module setting the code
Control Module harness is open or shorted
Control Module circuit poor electrical connection

How to Fix the DTC U3503?

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 U3503 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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Need Help with the Code?

Get the U3503 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U3503 Buick — Control Module Input Power 'A' Circuit Intermittent/Erratic
U3503 Cadillac — Control Module Input Power 'A' Circuit Intermittent/Erratic
U3503 Chevrolet — Control Module Input Power 'A' Circuit Intermittent/Erratic
U3503 GMC — Control Module Input Power 'A' Circuit Intermittent/Erratic

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 U3503 Code

1. What are the common symptoms of OBDII code U3503?

- Common symptoms include intermittent or erratic operation of the control module, such as power loss, stalling, or rough idle.

2. What can cause the Control Module Input Power 'A' Circuit to be intermittent or erratic?

- Possible causes include loose or corroded wiring connections, damaged wiring harness, faulty control module, or a failing power supply.

3. How can I diagnose the OBDII code U3503?

- A thorough inspection of the wiring harness, connectors, and control module is essential. Use a multimeter to check for continuity and voltage levels to identify the issue.

4. Can a weak battery or alternator cause code U3503 to appear?

- Yes, a weak battery or failing alternator can lead to intermittent power supply issues, triggering code U3503. Ensure the battery and charging system are in good working condition.

5. Is it safe to continue driving with OBDII code U3503 present?

- It is not recommended to drive with this code present, as it can lead to unpredictable behavior of the control module, potentially causing safety hazards or further damage to the vehicle.

6. How can I repair the Control Module Input Power 'A' Circuit Intermittent/Erratic issue?

- Start by inspecting and repairing any damaged wiring or connectors. If the problem persists, consider replacing the control module or addressing any power supply issues.

7. Can resetting the fault codes clear OBDII code U3503?

- Resetting the fault codes may temporarily clear the code, but if the underlying issue is not fixed, the code is likely to reappear. It's crucial to diagnose and address the root cause of the problem.

8. Are there any common vehicles known to experience OBDII code U3503?

- This code can appear in various makes and models, as it relates to a generic power input circuit issue. However, certain vehicle brands may have a higher likelihood of encountering this problem.

9. Will a simple fuse replacement resolve OBDII code U3503?

- While a blown fuse could potentially cause this issue, it's important to determine why the fuse blew in the first place. Simply replacing the fuse without addressing the root cause may not permanently fix the problem.

10. How can a professional mechanic help diagnose and repair OBDII code U3503?

- A skilled mechanic can conduct advanced diagnostics using specialized tools to pinpoint the exact cause of the issue. They can also provide expert advice on the most effective repair solutions tailored to your specific vehicle.