AutoCodes – GMC – P305F GMC

P305F GMC Code - Dual Battery Control Module Performance

Quick Answer

This system uses a dual battery configuration which includes the 12 V primary battery and 12 V auxiliary battery. Common causes include Low battery charge, Faulty Battery, Battery harness is open or shorted. 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: P305F GMC indicates Dual Battery Control Module Performance.
Common causes: Common causes include Low battery charge, Faulty Battery, Battery harness is open or shorted.
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 1,535

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 May 16, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P305F GMC Description

This system uses a dual battery configuration which includes the 12 V primary battery and 12 V auxiliary battery. The dual battery control module switches the 12 V primary battery and 12 V auxiliary battery in and out at appropriate times to support vehicle loads and battery charging. During engine crank, the auxiliary battery is switched in to supply voltage to the vehicle loads (except the starter motor which receives voltage from the primary battery) and the ECM monitors the auxiliary battery voltage through the IGN input.

OBDII Code P305F GMC - Dual Battery Control Module Performance - AutoCodes.com — P305F GMC Code - Dual Battery Control Module Performance

What does this mean?

What are the Possible Causes of the DTC P305F GMC?

Low battery charge
Faulty Battery
Battery harness is open or shorted
Battery circuit poor electrical connection

How to Fix the DTC P305F GMC?

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 P305F GMC 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 P305F GMC Code

1. What are the common symptoms of OBDII code P305F GMC (Dual Battery Control Module Performance)?

The common symptoms of code P305F include difficulty starting the vehicle, dimming lights, electrical system malfunctions, and potentially a discharged auxiliary battery.

2. What are the possible causes of OBDII code P305F GMC?

Some possible causes of code P305F include a faulty dual battery control module, issues with battery connections, wiring problems, or a malfunctioning auxiliary battery.

3. How can I diagnose OBDII code P305F GMC?

Diagnosing code P305F typically involves using a diagnostic scanner to retrieve the specific trouble code, checking the dual battery control module for any visible damage, inspecting battery connections, and testing the auxiliary battery's voltage and condition.

4. Can I still drive my vehicle with OBDII code P305F GMC?

It is not recommended to drive the vehicle with an unresolved P305F code, as it can lead to potential electrical issues and impact the vehicle's performance. It's best to address the problem promptly.

5. How can I repair OBDII code P305F GMC?

Repairing code P305F may involve replacing the dual battery control module, fixing any wiring or connection issues, or replacing the auxiliary battery if necessary. It's recommended to consult a professional mechanic for proper diagnosis and repair.

6. Is OBDII code P305F GMC a serious issue?

While code P305F may not cause immediate safety concerns, it can lead to electrical system malfunctions and affect the vehicle's overall performance. It's essential to address the issue to prevent further complications.

7. Can a DIY enthusiast fix OBDII code P305F GMC?

Depending on the root cause of the code, some DIY enthusiasts with automotive repair experience may be able to address code P305F by following proper diagnostic procedures and replacing components like the dual battery control module or auxiliary battery.

8. How much does it cost to repair OBDII code P305F GMC?

The cost of repairing code P305F can vary based on the specific cause of the issue, the parts needed for replacement, and labor costs. It's advisable to obtain multiple quotes from mechanics to determine the most cost-effective solution.

9. Will resetting the OBDII code P305F GMC resolve the issue?

Resetting the code may temporarily clear the warning light, but if the underlying problem causing code P305F is not addressed, the issue is likely to reoccur. It's crucial to diagnose and repair the root cause of the code.

10. How long does it take to repair OBDII code P305F GMC?

The repair time for code P305F can vary depending on the complexity of the issue, availability of parts, and the mechanic's expertise. In some cases, it may be a relatively quick fix, while in others, it may require more extensive diagnosis and repair.