AutoCodes – Buick – C0309 Buick

C0309 Buick Code - Motor A/B Circuit High

Quick Answer

The transfer case motor is a bi-directional, permanent magnet, D.C. Common causes include Faulty Transfer Case Motor, Transfer Case Motor harness is open or shorted, Transfer Case Motor 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: C0309 Buick indicates Motor A/B Circuit High.
Common causes: Common causes include Faulty Transfer Case Motor, Transfer Case Motor harness is open or shorted, Transfer Case Motor 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 895

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 C0309 Buick Description

The transfer case motor is a bi-directional, permanent magnet, D.C. motor. When energized, (through Motor Control A or Motor Control B, the ground is provided by the opposing Motor Control circuit and then grounded through the transfer case shift control module ground circuit), the motor, through a series of gears, rotates a shaft which moves the mode and range forks to shift the transfer case between 4H, AUTO 4WD, 2H, N, and 4L ranges. While the transfer case motor is energized the transfer case shift control module also energizes the solenoid for the transfer case lock. The motor lock is disabled (locking action released) and free turning of the transfer case motor and sector shaft is then allowed.
This DTC detects a short to ground in Motor Control A or Motor Control B CKT.

OBDII Code C0309 Buick - Motor A/B Circuit High - AutoCodes.com — C0309 Buick Code - Motor A/B Circuit High

What does this mean?

What are the Possible Causes of the DTC C0309 Buick?

Faulty Transfer Case Motor
Transfer Case Motor harness is open or shorted
Transfer Case Motor circuit poor electrical connection

How to Fix the DTC C0309 Buick?

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 C0309 Buick 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?

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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 C0309 Buick Code

1. What are common symptoms of OBDII code C0309 in a Buick related to the Motor A/B Circuit High?

The common symptoms include illuminated Check Engine Light, rough engine performance, and potential issues with the transmission shifting.

2. What are the possible causes of OBDII code C0309 in a Buick indicating Motor A/B Circuit High?

Potential causes include faulty motor components, damaged wiring or connectors in the motor circuit, or issues with the control module.

3. How can I diagnose the OBDII code C0309 in my Buick indicating Motor A/B Circuit High?

Diagnosis typically involves using a scan tool to retrieve the code, inspecting the motor circuit components, checking for loose connections, and testing the motor for proper operation.

4. Can I continue driving my Buick with OBDII code C0309 indicating Motor A/B Circuit High?

It is not recommended to drive the vehicle with this code present, as it can lead to further damage and potentially unsafe driving conditions.

5. What are the repair options for OBDII code C0309 in a Buick related to Motor A/B Circuit High?

Repair options may include replacing faulty motor components, repairing damaged wiring or connectors, or reprogramming the control module if necessary.

6. How much does it typically cost to fix OBDII code C0309 in a Buick indicating Motor A/B Circuit High?

The cost of repair can vary depending on the specific issue, but it may range from $100 to $500 or more, including parts and labor.

7. Can I reset the OBDII code C0309 in my Buick indicating Motor A/B Circuit High without fixing the underlying issue?

While you can clear the code using a scan tool, it will likely reappear if the root cause of the problem is not addressed.

8. Are there any preventive maintenance tips to avoid OBDII code C0309 in a Buick related to Motor A/B Circuit High?

Regularly inspecting and maintaining the motor components, checking for loose connections, and addressing any electrical issues promptly can help prevent this code from appearing.

9. How long does it take to repair OBDII code C0309 in a Buick indicating Motor A/B Circuit High?

The repair time can vary depending on the complexity of the issue and the availability of parts, but it may take anywhere from a few hours to a full day.

10. Can a DIY enthusiast fix OBDII code C0309 in a Buick indicating Motor A/B Circuit High?

While some aspects of the repair may be DIY-friendly, diagnosing and fixing electrical issues related to this code may require professional expertise and specialized tools.