AutoCodes – GMC – P305E GMC

P305E GMC Code - DC/DC Converter Crank Control Circuit Low Voltage

Quick Answer

The Power Supply Transformer is used to boost battery voltage to sensitive loads during engine restart. Common causes include Faulty Power Supply Transformer, Power Supply Transformer harness is open or shorted, Power Supply Transformer 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: P305E GMC indicates DC/DC Converter Crank Control Circuit Low Voltage.
Common causes: Common causes include Faulty Power Supply Transformer, Power Supply Transformer harness is open or shorted, Power Supply Transformer 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 9,205

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 P305E GMC Description

The Power Supply Transformer is used to boost battery voltage to sensitive loads during engine restart. It provides two voltage outputs that provide the boosted voltage. The Power Supply Transformer communicates to the Engine Control Module (ECM), and sends to the ECM the state of the crank control input.

OBDII Code P305E GMC - DC/DC Converter Crank Control Circuit Low Voltage - AutoCodes.com — P305E GMC Code - DC/DC Converter Crank Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P305E GMC?

Faulty Power Supply Transformer
Power Supply Transformer harness is open or shorted
Power Supply Transformer circuit poor electrical connection

How to Fix the DTC P305E 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 P305E 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 P305E GMC Code

1. What are common symptoms of OBDII code P305E GMC (DC/DC Converter Crank Control Circuit Low Voltage)?

The common symptoms include rough idling, engine misfires, reduced engine performance, and potential stalling.

2. What are the possible causes of OBDII code P305E GMC?

Possible causes of this code include faulty wiring or connectors in the DC/DC converter crank control circuit, a malfunctioning DC/DC converter, or issues with the powertrain control module (PCM).

3. How can I diagnose the root cause of OBDII code P305E GMC?

Diagnosing this code typically involves inspecting the wiring and connectors in the crank control circuit, testing the DC/DC converter for proper functionality, and scanning the PCM for any related error codes.

4. Can a DIYer repair OBDII code P305E GMC at home?

While some basic troubleshooting steps can be taken at home, diagnosing and repairing this code may require specialized tools and expertise. It is recommended to consult with a professional mechanic for accurate diagnosis and repair.

5. What are the repair options for OBDII code P305E GMC?

Repair options may include repairing or replacing damaged wiring or connectors, replacing the faulty DC/DC converter, or reprogramming the PCM if necessary.

6. How serious is OBDII code P305E GMC?

While the symptoms associated with this code can affect the drivability of the vehicle, the seriousness of the issue depends on the underlying cause. It is advisable to address this code promptly to prevent further damage to the vehicle.

7. Can driving with OBDII code P305E GMC cause further damage to the vehicle?

Continued driving with this code may potentially cause damage to other components of the vehicle, especially if the issue is related to the DC/DC converter. It is best to address the problem as soon as possible.

8. How much does it cost to repair OBDII code P305E GMC?

The cost of repairing this code can vary depending on the root cause of the issue, the extent of the damage, and the labor rates in your area. It is recommended to obtain quotes from different repair shops for an accurate estimate.

9. Are there any preventive measures to avoid OBDII code P305E GMC in the future?

Regular maintenance of the vehicle, including checking the electrical system and components, can help prevent issues like OBDII code P305E GMC. Additionally, addressing any warning signs promptly can help avoid further complications.

10. How long does it take to repair OBDII code P305E GMC?

The repair time for this code can vary depending on the specific cause of the issue and the availability of parts. It is best to consult with a mechanic for an estimated repair timeline.