AutoCodes – Generic – U3509

U3509 Code - Control Module Supply Circuit 3 Low Voltage

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: U3509 indicates Control Module Supply Circuit 3 Low Voltage.
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 1,644

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 U3509 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 U3509 - Control Module Supply Circuit 3 Low Voltage - AutoCodes.com — U3509 Code - Control Module Supply Circuit 3 Low Voltage

What does this mean?

What are the Possible Causes of the DTC U3509?

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

How to Fix the DTC U3509?

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 U3509 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 U3509 code?

Need more information on how to fix the U3509 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U3509 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U3509 Buick — Control Module Supply Circuit 3 Low Voltage
U3509 Cadillac — Control Module Supply Circuit 3 Low Voltage
U3509 Chevrolet — Control Module Supply Circuit 3 Low Voltage
U3509 GMC — Control Module Supply Circuit 3 Low Voltage

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 U3509 Code

1. What are the common symptoms of OBDII code U3509?

- Common symptoms include issues with starting the vehicle, poor engine performance, and illuminated malfunction indicator light (MIL).

2. What does OBDII code U3509 Control Module Supply Circuit 3 Low Voltage indicate?

- This code indicates that the control module is not receiving enough voltage from the power supply circuit.

3. What are the possible causes of OBDII code U3509?

- Possible causes include a faulty control module, damaged wiring or connectors in the supply circuit, or a weak battery.

4. How can I diagnose the cause of OBDII code U3509?

- Diagnose by checking the voltage levels at the control module and inspecting the wiring and connectors for any damage or corrosion.

5. Can a weak battery cause OBDII code U3509 to trigger?

- Yes, a weak or failing battery can cause the control module to receive low voltage, triggering code U3509.

6. How can I repair OBDII code U3509 Control Module Supply Circuit 3 Low Voltage?

- Repair involves addressing the root cause, which may include replacing the control module, repairing damaged wiring, or replacing the battery.

7. Is it safe to continue driving with OBDII code U3509 present?

- It is not recommended to continue driving with this code present, as it can lead to further electrical issues and potential damage to the vehicle.

8. Can a DIY enthusiast fix OBDII code U3509 at home?

- Depending on the cause, some DIY enthusiasts may be able to address the issue by checking and repairing wiring or replacing the battery. However, more complex issues may require professional assistance.

9. How much does it typically cost to repair OBDII code U3509?

- The cost of repair can vary depending on the cause of the issue. Repairs may range from a few hundred dollars for simple fixes to over a thousand dollars for more complex issues like control module replacement.

10. How long does it take to repair OBDII code U3509?

- The repair time can vary based on the specific cause and complexity of the issue. Simple fixes may take a few hours, while more involved repairs could take a day or longer.