AutoCodes – GMC – P0622 2017 GMC Sierra

P0622 2017 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 2017 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 271

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 2017 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 2017 GMC Sierra - Generator F-Terminal Circuit - AutoCodes.com — P0622 2017 GMC Sierra Code - Generator F-Terminal Circuit

What does this mean?

What are the Possible Causes of the DTC P0622 2017 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 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 P0622 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.

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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 2017 GMC Sierra Code

1. What does the OBDII code P0622 mean on a 2017 GMC Sierra?

P0622 indicates a problem with the generator F-terminal circuit, which is responsible for regulating the alternator's charging system.

2. What are the common symptoms of a P0622 code in a 2017 GMC Sierra?

Symptoms may include the battery warning light on the dashboard, a dead battery, dim headlights, or charging system issues.

3. What causes the P0622 code to appear?

Common causes include a faulty alternator, damaged wiring in the F-terminal circuit, a defective voltage regulator, or poor electrical connections.

4. Can I drive my 2017 GMC Sierra with a P0622 code?

Driving with a P0622 code is not recommended, as it can lead to a drained battery and cause the vehicle to stall unexpectedly.

5. How do I diagnose the P0622 code in a 2017 GMC Sierra?

Start by inspecting the alternator, F-terminal wiring, and connectors for damage or corrosion. Use a multimeter to check for proper voltage output and continuity in the circuit.

6. How do I fix the P0622 code on my GMC Sierra?

Repairs may include replacing the alternator, repairing damaged wiring, cleaning corroded connectors, or replacing the voltage regulator if itâ€™s built into the alternator.

7. Can a bad battery cause a P0622 code on a 2017 GMC Sierra?

A bad battery is unlikely to directly cause this code, but it can exacerbate charging system issues. Always test the battery when diagnosing charging problems.

8. How much does it cost to fix a P0622 code on a GMC Sierra?

The cost varies depending on the repair. An alternator replacement can cost $400â€“$800, while repairing wiring or connections is typically less expensive.

9. Does the P0622 code mean the alternator is bad?

Not always. While the alternator is a common culprit, the issue could also stem from wiring, connectors, or the voltage regulator within the charging system.

10. Can a software update fix the P0622 code in a 2017 GMC Sierra?

In rare cases, a software issue in the engine control module (ECM) might cause the code. Check with a dealership to see if a software update is available for your vehicle.