Mechanic Wiki: Program GAC Trumpchi GS4 Plus Smart Key with LAUNCH X431

Step-by-step guide to program a smart key for 2021-2025 GAC Trumpchi GS4 Plus using LAUNCH X431. Includes prerequisites, troubleshooting, and FAQs.

Published: June 16, 2026

Quick Answer: Programming a GAC Trumpchi GS4 Plus Smart Key with LAUNCH X431

You can program a smart key for a 2021–2025 GAC Trumpchi GS4 Plus using a LAUNCH X431 diagnostic scanner (Pro, V+, or Mini with updated GAC software). You’ll need at least one working original key and a compatible new blank fob. Connect the scanner, access the immobilizer menu, enter the security PIN if required, and follow on-screen instructions to learn the new key. The process takes 10–20 minutes. If it fails, update your scanner software, check battery voltage above 12.4V, and verify the new key’s compatibility.

Introduction

Losing a smart key or needing a spare for your GAC Trumpchi GS4 Plus can feel like a headache. The vehicle uses an advanced immobilizer system that ties the key’s transponder chip to the engine control unit (ECU). While some older cars let you program a key with simple ignition tricks, modern vehicles like the GS4 Plus require professional-grade diagnostic tools. The LAUNCH X431 series is one of the most popular choices among DIYers and independent technicians. In this guide, I’ll walk you through the exact steps, common pitfalls, and what to do when things don’t go as planned.

Understanding the Immobilizer System

Before diving into the procedure, it helps to grasp how the GS4 Plus smart key works. The key fob does more than lock and unlock doors—it contains a small transponder chip that communicates with the vehicle’s immobilizer antenna, usually located around the ignition switch or push-to-start button.

Smart Key Functions: Passive entry, remote lock/unlock, trunk release, and push-to-start.
Transponder Type: Most GS4 Plus keys use a 4D (Texas Instruments) or similar secure chip.
Why You Need a Scanner: The ECU must learn the new key’s unique ID. The LAUNCH X431 acts as a bridge, sending authorized commands over the OBD-II port to initiate the learning process.
Software Compatibility: Your X431 must have the latest GAC/Trumpchi software pack installed. If you haven’t updated in a while, connect to Wi-Fi and run a software update before starting.

Prerequisites Before You Start

Gathering the right tools and information beforehand saves you from frustration mid-programming.

Hardware You’ll Need

LAUNCH X431 Scanner: Any model (V+, Pro, Pro Mini) with the GAC software pack active.
OBD-II Cable or Bluetooth Connection: Wired is more stable during programming.
Working Original Smart Key: At least one functional key must be present.
New Blank Smart Key: OEM recommended, or a verified aftermarket key that matches the GS4 Plus frequency (usually 433 MHz or 315 MHz depending on region). Get the key blade cut by a locksmith before programming.
Fully Charged Battery: The vehicle battery should read above 12.4V. If it’s weak, connect a battery maintainer.

Software Preparation

Update your X431 firmware: Go to Settings → Software Update → Download and install any available GAC updates.
Launch the GAC diagnostic app from the scanner’s home screen.

Security PIN (If Required)

Some GS4 Plus models—especially 2022 and newer—ask for a security PIN (also called immobilizer code). Check the owner’s manual card in the glovebox, or look for a sticker in the toolkit bag. If you can’t find it, a GAC dealer can provide the PIN using your VIN. A few LAUNCH X431 units can calculate it, but that’s a paid add-on feature.

Step-by-Step Key Programming Process

Follow these steps exactly. Do not skip ahead or turn the ignition off prematurely.

Step 1: Connect the LAUNCH X431 to the Vehicle

Turn the ignition completely OFF.
Plug the scanner’s OBD-II cable into the diagnostic port under the dashboard (driver’s side).
Power on the X431. From the main menu, select Diagnostics → GAC → Trumpchi → GS4 Plus 2021–2025.
Wait for the system to identify the vehicle. The VIN may auto-populate—confirm it matches your car’s VIN.

Step 2: Access the Immobilizer or Key Programming Menu

From the diagnostic menu, choose Immobilizer or Body Control Module (BCM) depending on the software version.
Look for an option labeled Key Learning, Program Smart Key, or Add Key.
If prompted, enter the security PIN (see prerequisites). Leave this field blank if the scanner doesn’t ask for it.

Step 3: Follow the On-Screen Instructions for Key Learning

The scanner will display a series of prompts. Typically, it will ask you to:
1. Insert the first original smart key into the ignition slot or hold it near the start button (for push-to-start models).
2. Turn the ignition to the ON position (do not start the engine).
3. Wait for confirmation: “Original Key Learned” or “Key 1 OK”.
4. Remove that key.
5. Insert the new blank key and repeat the same action.
6. Some procedures require a rapid ON-OFF sequence. For example, turn the ignition ON for 2 seconds, OFF for 5 seconds, then ON again. Follow the scanner’s timing exactly.

Step 4: Verify Programming Success

After the last key is learned, the scanner will display “Key Programming Successful”.
Exit the diagnostic app and disconnect the scanner.
Test every function: lock/unlock with remote, push-to-start the engine, open the trunk, and try passive entry (approach vehicle with key in pocket).
If the engine starts and all functions work, you’re done.

Detailed Troubleshooting Steps

Even when you follow the instructions, things can go wrong. Here are the most common hiccups and how to fix them.

Issue 1: Scanner Fails to Connect or Shows “No Communication”

Likely Cause: Software mismatch or low voltage.
Fix: Update the X431 to the latest GAC software pack. Check battery voltage—if below 12.4V, use a battery charger. Restart both the scanner and vehicle.

Issue 2: Original Key Not Recognized During Programming

Likely Cause: Weak transponder or incorrect ignition sequence.
Fix: Try holding the original key closer to the start button for 30 seconds before turning ignition ON. Clean the key fob contacts. If it fails repeatedly, the original key may have a dying battery or damaged chip—try another original key if you have one.

Issue 3: New Key Fails to Program (Error Code 322 or Similar)

Likely Cause: Incompatible blank key, wrong PIN, or key memory full.
Fix: Verify the new key’s FCC ID matches the OEM part number (look inside the fob). Obtain the correct PIN from the dealer. If memory is full (max 4 keys), use the scanner’s “Delete All Keys” function, then reprogram all keys from scratch.

Issue 4: Functions Work but Engine Won’t Start

Likely Cause: Immobilizer chip not fully linked to the push-to-start sensor.
Fix: Reprogram the problematic key. During the learning step, hold the key directly against the start button for 30 seconds. If that fails, the start button’s antenna may be defective—rare, but possible.

Issue 5: Scanner Freezes Mid-Programming

Likely Cause: Bluetooth interference or outdated firmware.
Fix: Switch to a wired OBD-II connection if using Bluetooth. Force-close the diagnostic app, restart the X431, and start over. Do not remove the key or turn off ignition during the freeze.

Issue 6: IMMO Warning Light Stays On After Programming

Likely Cause: One or more keys not fully learned.
Fix: Run the “Read Key Count” function. If the stored count is less than the number of physical keys, reprogram all keys again.

Common Mistakes to Avoid

Using an uncut key blade: The key must be cut to fit the ignition or door lock before programming.
Starting the engine: Keep your foot off the brake and never crank the engine during programming.
Interrupting power: Do not unplug the scanner or turn the ignition off mid-session. This can corrupt the ECU.
Skipping the PIN: Many 2022+ GS4 Plus models require a PIN. Guessing or entering zeros will lock you out temporarily.

Alternative Methods and When to Use Them

If the LAUNCH X431 fails or you don’t have one, consider these options:

GAC Dealer: Uses official MDI tool. Costs more but guaranteed to work, especially for all-keys-lost scenarios.
Other OBD Scanners: Some Autel or ThinkCar units support GAC, but compatibility varies.
Aftermarket Programming Kits: Cheap “one-button” kits rarely work on the GS4 Plus. Stick with professional tools.

For a detailed comparison of LAUNCH X431 models, check out our guide on [link to related guide on LAUNCH X431 models for key programming].

Frequently Asked Questions (FAQ)

Q1: Can I program a smart key without the original key?

No. The LAUNCH X431 requires at least one working original key to authenticate the procedure. If you’ve lost all keys, you’ll need dealer-level tools that can perform an “all-keys-lost” reset, typically involving a security PIN and BCM rewrite.

Q2: How many smart keys can the GAC Trumpchi GS4 Plus store?

The system can store up to 4 keys. If you try to add a fifth, the scanner will give an error. You’ll need to delete a key using the “Delete Key” function before adding another.

Q3: Does the LAUNCH X431 require an active subscription for GAC programming?

Yes. Most LAUNCH X431 models operate on a subscription model. You need an active software plan (annual or one-time purchase) that includes GAC/Trumpchi diagnostic functions. Check your subscription status before starting.

Q4: Can I use a smart key from another GAC model like the GS3 or GS8?

No. Each model uses a different frequency and transponder type. Only use a key specifically listed for the GS4 Plus (2021–2025). Using an incompatible key will either fail to program or cause communication errors.

Q5: What does “Key Learning Failed – VIN Mismatch” mean?

This error indicates that the scanner’s software version doesn’t match the vehicle’s ECU firmware. Update your X431 to the latest GAC+ software pack. If the error persists, perform a full system scan first to let the scanner re-identify the vehicle.

Q6: Is it safe to program with the engine running?

No. Always program with ignition ON and engine OFF. Running the engine can cause voltage spikes that interrupt the procedure and may damage the scanner or ECU.

Q7: How do I obtain the security PIN for my GS4 Plus?

Check the owner’s manual card in the glovebox, the toolkit bag, or a sticker inside the glovebox door. If missing, contact a GAC dealer with your VIN. Some LAUNCH X431 units offer PIN calculation as a paid feature.

Final Checklist

Before you start, run through this list:

Scanner updated with latest GAC software and active subscription
Vehicle battery voltage 12.5V or higher (use a maintainer if needed)
Original working key available and functional
New blank key verified compatible (OEM or reputable aftermarket)
Security PIN ready (if required for your model year)
All doors closed, foot off brake, ignition OFF initially
Successfully test lock/unlock, remote start, and push-to-start after programming

Note: This guide is based on common LAUNCH X431 programming logic for GAC Trumpchi GS4 Plus (2021–2025). Actual steps may vary slightly by X431 model and software version. Always follow the on-screen prompts on your scanner as the primary reference.

About the Author: Erwin Salarda is an Automotive Service Equipment Technician based in the Philippines, specializing in computerized automotive diagnostic equipment such as OBD scanners and wheel alignment systems. Since 2012, he has been actively providing technical support, equipment installation, troubleshooting, after-sales service, and hands-on training for automotive service equipment used by workshops and automotive professionals.

He has received specialized training from international suppliers and manufacturers, including Launch X431 in Shenzhen, China, Lawrence Engineering Company in Guangzhou, China, and 3Excel Wheel Alignment Company in Shenzhen, China. Through these trainings, he developed advanced expertise in automotive diagnostics, calibration, wheel alignment systems, and computerized automotive service technologies.

Erwin Salarda provides professional after-sales support and technical training for automotive diagnostic and wheel alignment equipment, helping clients maximize the performance and proper use of their tools and systems. His experience covers equipment setup, software updates, calibration procedures, troubleshooting, and operational guidance for automotive workshops and service centers.

With more than a decade of experience in the automotive equipment industry, Erwin Salarda continues to support automotive businesses by delivering reliable technical expertise and practical training solutions.

For inquiries and equipment purchases, please visit https://carlifterph.com/