AutoCodes – GMC – P0622 2018 GMC Sierra

P0622 2018 GMC Sierra Code - Generator F-Terminal Circuit

Quick Answer

The Engine Control Module (ECM) uses the Generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the Generator. Common causes include Battery charge, Faulty Generator, Generator 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: P0622 2018 GMC Sierra indicates Generator F-Terminal Circuit.
Common causes: Common causes include Battery charge, Faulty Generator, Generator 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 230

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
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0622 2018 GMC Sierra Description

The Engine Control Module (ECM) uses the Generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the Generator. The Generator field duty cycle signal circuit connects to the high side of the field windings in the generator. A Pulse Width Modulated (PWM) high side driver in the voltage regulator turns the field windings ON and OFF. The ECM uses the PWM signal input to determine the generator load on the engine. This allows the ECM to adjust the idle speed to compensate for high electrical loads. The ECM monitors the status of the generator field duty cycle signal circuit. When the ignition is ON and the engine is OFF, the ECM should detect a duty cycle near 0%. When the engine is running, the duty cycle should be between 5 - 99%. The Diagnostic Trouble Code (DTC) will be set if the ignition is ON, and the engine OFF (Prior to Ignition ON, the ignition must have been OFF for at least 5 s), the ECM detects a PWM signal that is greater than 65% for 5 s.

OBDII Code P0622 2018 GMC Sierra - Generator F-Terminal Circuit - AutoCodes.com — P0622 2018 GMC Sierra Code - Generator F-Terminal Circuit

What does this mean?

What are the Possible Causes of the DTC P0622 2018 GMC Sierra?

Battery charge
Faulty Generator
Generator harness is open or shorted
Generator circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0622 2018 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 P0622 2018 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 P0622 2018 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 P0622 2018 GMC Sierra Code

What does OBDII code P0622 mean for a 2018 GMC Sierra?

OBDII code P0622 indicates a problem with the generator F-terminal circuit, which is responsible for communication between the engine control module (ECM) and the generator.

What are common symptoms of the P0622 code?

Common symptoms include illuminated check engine light, potential battery warning light, and issues with battery charging or starting the vehicle.

What could cause the P0622 code to trigger?

Possible causes include a faulty generator, damaged wiring or connectors in the F-terminal circuit, or a malfunctioning engine control module (ECM).

How can I diagnose the P0622 code?

To diagnose the P0622 code, inspect the wiring and connectors for damage, test the generator's output, and check the ECM for any faults or communication issues.

What repairs can fix the P0622 code?

Repairs may involve replacing a faulty generator, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the ECM.

Is it safe to drive with the P0622 code?

While it may be safe to drive short distances, you should address the issue promptly, as it can lead to battery drain or starting problems.

Can a bad battery cause the P0622 code?

Yes, a weak or failing battery can affect the generator's performance and potentially trigger the P0622 code.

How can I prevent the P0622 code from appearing again?

Regular maintenance, including checking the electrical system, ensuring clean and tight connections, and replacing worn components, can help prevent the P0622 code from reoccurring.

Will clearing the P0622 code fix the problem?

Clearing the code may turn off the check engine light temporarily, but it wonâ€™t fix the underlying issue. Proper diagnosis and repair are necessary to prevent the code from returning.