AutoCodes – GMC – P129C 2014 GMC Sierra

P129C 2014 GMC Sierra Code - Fuel Pump Driver Control Module System Voltage High

Quick Answer

The Fuel Pump Power Control Module monitors the battery positive voltage circuit to verify the voltage is within the normal operating range. Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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: P129C 2014 GMC Sierra indicates Fuel Pump Driver Control Module System Voltage High.
Common causes: Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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 168

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 Jul 04, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P129C 2014 GMC Sierra Description

The Fuel Pump Power Control Module monitors the battery positive voltage circuit to verify the voltage is within the normal operating range. The Diagnostic Trouble Code (DTC) will be set when the Fuel Pump Driver Control Module detects the battery positive voltage is greater than 18 V for 1 s.

OBDII Code P129C 2014 GMC Sierra - Fuel Pump Driver Control Module System Voltage High - AutoCodes.com — P129C 2014 GMC Sierra Code - Fuel Pump Driver Control Module System Voltage High

What does this mean?

What are the Possible Causes of the DTC P129C 2014 GMC Sierra?

Faulty Fuel Pump Driver Control Module
Fuel Pump Driver Control Module harness is open or shorted
Fuel Pump Driver Control Module circuit poor electrical connection

How to Fix the DTC P129C 2014 GMC Sierra?

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 P129C 2014 GMC Sierra 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 P129C 2014 GMC Sierra code?

Need more information on how to fix the P129C 2014 GMC Sierra code? Get Access to Factory Service Manuals

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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 P129C 2014 GMC Sierra Code

1. What does the OBDII code P129C mean on a 2014 GMC Sierra?

P129C indicates that the Fuel Pump Driver Control Module (FPCM) has detected a system voltage that is higher than the expected range.

2. What are the symptoms of code P129C on a 2014 GMC Sierra?

Symptoms may include difficulty starting the engine, reduced fuel efficiency, poor engine performance, and possible activation of the Check Engine Light.

3. What causes the P129C code to appear on a 2014 GMC Sierra?

Common causes include a faulty Fuel Pump Driver Control Module, wiring issues such as short circuits, a failing fuel pump, or an issue with the vehicle's charging system, like a faulty alternator.

4. Can I drive my 2014 GMC Sierra with the P129C code?

Driving with this code is not recommended as it may lead to reduced engine performance or damage to the fuel system components.

5. How do I diagnose the P129C code on a 2014 GMC Sierra?

Start by inspecting the wiring and connectors for damage, test the Fuel Pump Driver Control Module, check the fuel pump, and verify the voltage levels in the system using a multimeter.

6. How is the P129C code fixed on a 2014 GMC Sierra?

Repairs may involve replacing the Fuel Pump Driver Control Module, repairing damaged wiring, replacing the fuel pump, or addressing issues with the vehicle's alternator or battery.

7. Can a bad alternator cause the P129C code on a 2014 GMC Sierra?

Yes, a malfunctioning alternator can cause high voltage in the system, which may trigger the P129C code.

8. How much does it cost to fix the P129C code on a 2014 GMC Sierra?

Repair costs can vary but may range from $100 to $500 depending on whether the issue is with the Fuel Pump Driver Control Module, wiring, or other components.

9. What tools are needed to troubleshoot the P129C code on a 2014 GMC Sierra?

Basic tools include a diagnostic scanner to read codes, a multimeter to test voltage, and basic hand tools for inspecting and repairing wiring or modules.

10. Can a weak battery trigger the P129C code on a 2014 GMC Sierra?

A weak battery is unlikely to cause this specific code, but voltage fluctuations from a failing charging system could contribute to the issue.