AutoCodes – GMC – P0622 2016 GMC Sierra

P0622 2016 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 2016 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 290

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 2016 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 2016 GMC Sierra - Generator F-Terminal Circuit - AutoCodes.com — P0622 2016 GMC Sierra Code - Generator F-Terminal Circuit

What does this mean?

What are the Possible Causes of the DTC P0622 2016 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 2016 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 2016 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 2016 GMC Sierra Code

1. What does the OBDII code P0622 mean on a 2016 GMC Sierra?

The code P0622 indicates a problem with the generator F-terminal circuit, which is involved in the communication between the alternator and the vehicle's powertrain control module (PCM).

2. What are the symptoms of a P0622 code in a 2016 GMC Sierra?

Common symptoms include the battery warning light illuminating on the dashboard, poor charging performance, dim headlights, or a dead battery.

3. What causes the P0622 code on a 2016 GMC Sierra?

Potential causes include a faulty alternator, damaged or corroded wiring in the F-terminal circuit, a defective PCM, or a bad voltage regulator inside the alternator.

4. Can I drive my 2016 GMC Sierra with a P0622 code?

It is not recommended to drive with this code, as it could lead to battery depletion and potential vehicle shutdown due to lack of power.

5. How do I diagnose the P0622 code on my 2016 GMC Sierra?

Start by inspecting the alternator wiring and connections for damage or corrosion. Use a multimeter to check for proper voltage and continuity in the F-terminal circuit. If no wiring issues are found, test the alternator and PCM functionality.

6. How do I fix a P0622 code on a 2016 GMC Sierra?

Repairs may include replacing the alternator, repairing or replacing damaged wiring in the F-terminal circuit, cleaning corroded connections, or reprogramming or replacing the PCM if necessary.

7. How much does it cost to repair a P0622 code on a 2016 GMC Sierra?

The cost varies depending on the issue. Replacing an alternator typically costs $400â€“$800, while wiring repairs may be less expensive. PCM replacement can cost $500â€“$1,200 depending on labor and programming.

8. Can a weak battery cause the P0622 code on a 2016 GMC Sierra?

While a weak battery alone does not usually cause this code, it can exacerbate charging issues. Always ensure the battery is in good condition when diagnosing charging system problems.

9. Does the P0622 code always mean the alternator is bad on a 2016 GMC Sierra?

No, the code can also be triggered by wiring issues, a faulty PCM, or voltage regulator problems. Proper diagnosis is essential to pinpoint the exact cause.

10. Can I reset the P0622 code on my 2016 GMC Sierra without fixing it?

You can clear the code with a scan tool, but it will likely return unless the underlying issue is resolved. Ignoring the problem can lead to further electrical issues.