AutoCodes – GMC – P0622 GMC

P0622 GMC 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 GMC 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 12,097

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
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0622 GMC 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 GMC - Generator F-Terminal Circuit - AutoCodes.com — P0622 GMC Code - Generator F-Terminal Circuit

What does this mean?

What are the Possible Causes of the DTC P0622 GMC?

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 GMC?

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 does this mean?

Code Tech Notes

If the battery is OK then the alternator is more than likely the problem.

There is a Factory Service Bulletin for the following GMC models:
2010 GMC Savana
2011 GMC Savana
2011 GMC Sierra
GMC Factory Service Bulletin OBDII Code P0622

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0622 GMC 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 GMC code?

Need more information on how to fix the P0622 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0622 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P0622 2014 GMC Sierra — Generator F-Terminal Circuit
P0622 2015 GMC Sierra — Generator F-Terminal Circuit
P0622 2016 GMC Sierra — Generator F-Terminal Circuit
P0622 2017 GMC Sierra — Generator F-Terminal Circuit
P0622 2018 GMC Sierra — Generator F-Terminal Circuit

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 GMC Code

1. What are the common symptoms of OBDII code P0622 GMC?

The common symptoms of OBDII code P0622 GMC include issues with starting the vehicle, dim or flickering lights, and a discharged battery.

2. What does the OBDII code P0622 GMC indicate?

OBDII code P0622 GMC indicates a malfunction in the Generator F-Terminal circuit, which is responsible for controlling the charging system of the vehicle.

3. What are the possible causes of OBDII code P0622 GMC?

Possible causes of OBDII code P0622 GMC include a faulty generator, damaged wiring or connectors in the F-Terminal circuit, or a defective ECM (Engine Control Module).

4. How can I diagnose the OBDII code P0622 GMC?

Diagnosing OBDII code P0622 GMC involves using an OBDII scanner to retrieve the code, inspecting the generator and F-Terminal circuit for any visible damage, and testing the ECM for proper functioning.

5. What are the repair options for OBDII code P0622 GMC?

Repair options for OBDII code P0622 GMC may include replacing the faulty generator, repairing or replacing damaged wiring or connectors in the F-Terminal circuit, or reprogramming the ECM if necessary.

6. Can I continue driving with OBDII code P0622 GMC?

It is not recommended to continue driving with OBDII code P0622 GMC, as it can lead to further damage to the vehicle's electrical system and potentially result in a dead battery or stalling while driving.

7. How much does it cost to repair OBDII code P0622 GMC?

The cost to repair OBDII code P0622 GMC can vary depending on the specific cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

8. Can OBDII code P0622 GMC be triggered by a loose battery connection?

Yes, a loose or corroded battery connection can sometimes trigger OBDII code P0622 GMC due to disruptions in the electrical flow to the F-Terminal circuit.

9. Are there any preventive maintenance tips to avoid OBDII code P0622 GMC?

To prevent OBDII code P0622 GMC, it is recommended to regularly inspect the battery connections, generator, and wiring for any signs of damage or corrosion, and to address any issues promptly.

10. Is it possible for a DIY enthusiast to repair OBDII code P0622 GMC?

Repairing OBDII code P0622 GMC may require advanced knowledge and tools, so it is recommended to consult a professional mechanic for proper diagnosis and repair.