AutoCodes – GMC – P0629 2017 GMC Sierra

P0629 2017 GMC Sierra Code - Fuel Pump Speed Output Circuit High Voltage

Quick Answer

The Engine Control Module (ECM) supplies voltage to the fuel pump driver control module for 30 s when the ignition is on and continuously when the engine is running. 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: P0629 2017 GMC Sierra indicates Fuel Pump Speed Output Circuit High Voltage.
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 194

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 15, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0629 2017 GMC Sierra Description

The Engine Control Module (ECM) supplies voltage to the fuel pump driver control module for 30 s when the ignition is on and continuously when the engine is running. While this voltage is being received, a serial data signal containing the desired fuel pump speed is also received from the ECM. After the voltage and data have been received the fuel pump driver control module actuates the brushless fuel pump by means of a high power three phase signal. The Diagnostic Trouble Code (DTC) will be set when the Fuel Pump Speed Output Circuit is short to voltage for greater than 2 s.

OBDII Code P0629 2017 GMC Sierra - Fuel Pump Speed Output Circuit High Voltage - AutoCodes.com — P0629 2017 GMC Sierra Code - Fuel Pump Speed Output Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0629 2017 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
Faulty Engine Control Module (ECM)

How to Fix the DTC P0629 2017 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 P0629 2017 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 P0629 2017 GMC Sierra 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 P0629 2017 GMC Sierra Code

What does the OBDII code P0629 mean on a 2017 GMC Sierra?

P0629 indicates that the Fuel Pump Speed Output Circuit is experiencing high voltage, which may affect the fuel pump's operation.

What are the common symptoms of a P0629 code in a 2017 GMC Sierra?

Symptoms may include difficulty starting, engine stalling, reduced engine performance, or the check engine light being illuminated.

What causes the P0629 code on a 2017 GMC Sierra?

Common causes include a faulty fuel pump relay, wiring issues like short circuits or damaged connectors, a malfunctioning fuel pump, or a defective powertrain control module (PCM).

Can I drive my 2017 GMC Sierra with a P0629 code?

While the vehicle may still be drivable, it's not recommended as the issue could lead to engine stalling or further damage to the fuel system.

How can I diagnose the P0629 code on my GMC Sierra?

Start by checking the fuel pump relay and inspecting all related wiring and connectors for damage or corrosion. Use a multimeter to test for proper voltage at the circuit.

How do I fix the P0629 code on a 2017 GMC Sierra?

Repairs may include replacing a faulty fuel pump relay, repairing damaged wiring or connectors, replacing the fuel pump, or reprogramming or replacing the PCM if necessary.

How much does it cost to repair a P0629 code on a 2017 GMC Sierra?

Repair costs vary based on the cause. Replacing a fuel pump relay might cost $50-$150, while replacing the fuel pump or PCM could exceed $500.

Can a bad fuel pump cause the P0629 code to appear?

Yes, a malfunctioning fuel pump can cause high voltage in the circuit and trigger the P0629 code.

Will clearing the P0629 code solve the issue in my GMC Sierra?

Clearing the code may turn off the check engine light temporarily, but the underlying issue must be addressed to prevent the code from returning.

Can a failing PCM cause the P0629 code on a 2017 GMC Sierra?

Yes, a defective PCM can misinterpret or send incorrect signals, resulting in the P0629 code. However, this is less common and should be diagnosed last.