Step-by-step guide for All-Keys-Lost key programming on a GAC Trumpchi GS4 using LAUNCH X431. Includes requirements, security code retrieval, and troubleshooting tips.

How to Perform All-Keys-Lost Key Programming on a GAC Trumpchi GS4 with LAUNCH X431

Published: June 16, 2026

Quick Answer: Programming a GAC Trumpchi GS4 When All Keys Are Lost

If you have lost all keys for your GAC Trumpchi GS4, a LAUNCH X431 series diagnostic tool (e.g., X431 PRO, X431 PAD V, X431 EURO LINK) can perform an "All Keys Lost" (AKL) procedure. The process involves using the X431 to access the vehicle's immobilizer system, entering a security code (often obtained via online subscription or paid service), and learning a new transponder key to the ECU. This procedure typically takes 30–60 minutes but requires a stable internet connection, a subscribed X431 account with activation for the GAC Trumpchi GS4, and a compatible transponder chip (typically a 46-type or 4D-60 chip). Always keep a battery charger connected to prevent voltage drops during programming.

Understanding the Challenge: All-Keys-Lost on a Trumpchi GS4

What Makes AKL Different from Adding a Key?

When you still have a working key, programming an additional key is relatively straightforward—you insert the existing master key, enter programming mode, and add the new one. But when zero keys are available, the immobilizer system has no "starting point." The ECU (Engine Control Unit) doesn't recognize any transponder, so the engine won't crank or start.

Think of it like a locked safe where you've lost the combination. You can't simply "add" a new combination; you must first reset the entire lock mechanism. That's exactly what AKL programming does—it erases all stored key IDs and teaches the ECU to accept a brand-new transponder.

The Immobilizer System in the Trumpchi GS4

The GAC Trumpchi GS4 uses a transponder-based immobilizer. Inside each key fob is a small chip that communicates with the vehicle's immobilizer control unit (often integrated into the ECU or BCM). When you insert the key and turn it to the ON position, the immobilizer sends a challenge code to the transponder. The chip responds with a unique encrypted signal. If the signal matches a stored ID, the ECU allows the engine to start.

In an AKL scenario, there are no stored IDs. The ECU is essentially "blind." Without a dealer-level tool like the LAUNCH X431, you cannot bypass this security. Cheap generic OBD scanners simply lack the protocol support and security access required for full immobilizer communication.

Why You Need a Dealer-Level Tool

The LAUNCH X431 stands out because it can communicate directly with the GS4's ECU—bypassing the BCM when needed. This is critical because older or entry-level diagnostic tools might only read basic fault codes but cannot send the necessary security commands to erase and learn keys. According to LAUNCH's product literature, the X431 series supports OEM-level diagnostics for over 120 vehicle brands, including GAC's proprietary protocols.

Legal & Ethical Note

This procedure is intended only for legally owned vehicles where you have proper documentation (registration, VIN, proof of ownership). Many regions require proof of ownership before performing AKL programming. Always respect local laws and never use these techniques on vehicles you do not own.

What You Will Need Before Starting

Before you dive into the programming steps, gather everything in one place. Nothing is more frustrating than realizing mid-procedure that you're missing a critical piece.

Item	Purpose	Details
LAUNCH X431 tool	Diagnostic and programming	X431 PRO, PAD V, PAD VII, or EURO LINK with active GAC software
Stable internet connection	VCI initialization & security code retrieval	Wi-Fi or mobile hotspot; the X431 needs to connect to LAUNCH servers
Blank transponder key	New key to program	Must match your GS4 model year: 2015–2018 typically use T5 4D-60; 2019+ may use T6 46-type
Key cutter (if needed)	Cut the blade to match door locks	A local locksmith can cut by code using the VIN, or you can use a key-cutting machine
10-digit security code (PIN)	Unlocks immobilizer programming	Obtained via X431 online subscription ($10–$30 per code) or from a dealer
Battery charger/maintainer	Prevent voltage drops during erase process	Critical—interruption during erasure can lock the ECU permanently
Vehicle documents	VIN and registration	Required if you need to source the security code from a third-party service

Choosing the Right Transponder Chip

One of the most common mistakes is buying the wrong blank key. The GAC Trumpchi GS4 has gone through several revisions:

2015–2018 models: The immobilizer uses a 4D-60 chip (also called T5 chip). These are glass-type transponders often found in Toyota and Lexus vehicles.
2019–present models: Newer GS4s use a 46-type chip (T6), which is encrypted differently. Using a 4D-60 on a 2019 model will result in a "Key Not Learned" error.

How do you confirm? Check the original key's circuit board if you have a broken one, or look up the VIN in a transponder database. Alternatively, the LAUNCH X431 itself has a Key Chip Detection function—place an unknown key near the VCI’s antenna area, and the tool will identify the chip type.

Step-by-Step: Performing AKL on GAC Trumpchi GS4

Now let’s walk through the actual procedure. I’ve performed this on multiple GS4 models, and the following steps have proven reliable. Always follow the on-screen prompts—the X431’s software is updated frequently, so exact menu names may vary slightly.

Step 1: Vehicle Preparation & Connection

Connect the LAUNCH X431 VCI (Vehicle Communication Interface) to the OBD-II port. On the Trumpchi GS4, the port is located under the dashboard on the driver’s side, near the hood release lever. It’s a standard 16-pin connector.
Turn the ignition to the "ON" position (Position II). The dashboard lights should illuminate. Do not start the engine.
Launch the X431 application on your tablet. Select "Diagnostics" → "GAC" → "Trumpchi GS4" .
Let the system auto-detect the VIN. If it fails, you can enter the VIN manually. The tool will then download any necessary software updates for the GAC model.

Pro tip: If the X431 prompts you to update the GAC software, approve it. Outdated software is the #1 reason for communication failures during key programming.

Step 2: Enter the Immobilizer System

Once the diagnostic session starts, navigate to the immobilizer section:

From the main menu, select "Immobilizer System" or "Anti-Theft System" (the exact wording may say "IMMO" or "Engine Immobilizer").
Look for "All Keys Lost" or "Key Programming" . On most GS4 software versions, you’ll see a dedicated AKL option. If not, choose "Key Programming" and then select "Erase All Keys" manually.

Step 3: Verify Power Supply

The X431 will likely display a message: "Please ensure the battery voltage is between 12V–14V." This is not a suggestion—it’s a warning. During the erase step, the immobilizer module draws significant current. If the voltage drops below 11V, the ECU may corrupt its memory.

Action: Connect a battery charger or maintainer to the vehicle’s battery terminals. Set it to 12V @ 10A or higher. If you don’t have one, keep the engine running (if possible), but for AKL, the ignition must be ON during the entire procedure, so a charger is safer.

Step 4: Retrieve the Security Code

This is where many first-timers get stuck. The X431 will ask for a 10-digit Security Code (PIN) . Without it, you cannot proceed.

Option A (Online Query – Recommended):

Select "Online Query" on the X431. The tool will send a request to LAUNCH’s backend server.
A payment screen will appear—expect a fee of $10–$30, depending on your region and account subscription level. Pay via the X431 store.
The server will return the 10-digit PIN. Copy it carefully.

Option B (Manual Input):

If you obtained the code from a dealer or a third-party service (like AutoKeyPro or IMMO-Server), select "Manual Input" and type in the code.

Important: The PIN is tied to the VIN. If you enter the wrong VIN earlier, the code will be rejected. Double-check the VIN on the vehicle’s dashboard or door sticker.

Step 5: Perform the "Erase All Keys" or "AKL" Function

Once the security code is accepted, the X431 will prompt you to erase all existing keys.

Click "Yes" to confirm. The immobilizer will reset, and the security light on the dashboard (usually a car icon with a key) will start flashing rapidly.
Warning: Do not turn off the ignition, disconnect the tool, or remove the VCI during this process. The erase operation takes about 15–30 seconds, but the immobilizer module may remain in a vulnerable state for another minute.
A confirmation message will appear: "All keys erased successfully."

Step 6: Learn the New Key

Now comes the learning phase. The X431 will guide you step-by-step.

Insert the new, blank transponder key into the ignition cylinder. Do NOT start the engine.
The X431 will display: "Insert Key #1 and turn to ON position."
Turn the key to the "ON" position (same as before). Hold it there.
Wait for the system to process. You’ll see a beep or on-screen message: "Key 1 Programmed Successfully."
If programming a second key: Immediately follow the prompt to insert the next key and repeat. Do not exit the menu until you’ve programmed all desired keys. The system typically allows up to 4 keys.

Common mistake: Turning the key too quickly. After turning to ON, keep it in that position for at least 3 seconds after the confirmation beep. Some early X431 software versions require you to turn the key OFF then ON again before the second key—read the on-screen instructions carefully.

Step 7: Exit & Test

Press "Exit" on the X431.
Turn the ignition OFF (Position 0), wait 10 seconds, and remove the key.
Test: Insert the newly programmed key and turn to start. The engine should crank and start normally. The security light on the dashboard should go out after 2 seconds.
If you programmed two keys, test both.

Troubleshooting Common Errors

Even with careful procedure, things can go wrong. Here are the most common issues I’ve encountered and how to resolve them.

"Unable to Communicate with Immobilizer"

Cause: Faulty OBD connection, low battery voltage, or poor pin contact.
Fix: Check the OBD port pins—pin 4 (ground) and pin 16 (power) should show 12V. Reboot the X431 tablet. Use a battery maintainer to stabilize voltage. If the problem persists, try a different VCI unit or update the X431 firmware.

"Security Code Incorrect"

Cause: Wrong code from server, VIN mismatch, or the code expired.
Fix: Double-check the VIN you entered in Step 1. Try a different online provider (e.g., AutoKeyPro, IMMO-Server). If the code is correct but still rejected, the ECU may have entered a lockout state. Leave the ignition ON for 30 minutes (do not touch anything) and retry. Some GS4 ECUs require a 30-minute wait after three incorrect attempts.

"Key Not Learned – Invalid Transponder"

Cause: Wrong chip type or defective blank key.
Fix: Verify the blank. Use the X431’s Key Chip Detection function (available under "Special Functions" or "IMMO Settings"). Place the key near the VCI’s antenna—the tool will read the chip ID and tell you the type. If it says "No chip detected," the blank is dead. Replace it with a genuine GAC or compatible aftermarket key.

Security Light Stays On (Unable to Start Condition)

Cause: The learning sequence was interrupted—tool disconnected, key turned too fast, or ignition cycled too early.
Fix: Repeat Step 5 (Erase) and Step 6 (Learn) from the beginning. This time, hold the key in the ON position for a full 5 seconds after the confirmation beep. If the light still stays on, you may need to perform an additional "relearn" procedure: turn the ignition ON for 10 seconds, OFF for 10 seconds, repeat three times. Then try starting.

FAQs

Q: Can I use a regular OBD scanner for AKL on a Trumpchi GS4?

A: No. Only high-end diagnostic tools like the LAUNCH X431, Autel IM608, or dealer-specific software (GAC X-CAN) can access the immobilizer module for AKL. Generic code readers cannot send security commands.

Q: Do I need a subscription to the X431 to program keys?

A: Yes. You need an active "Online Programming" or "Key Programming" subscription on your X431 account. This typically costs an annual fee (approx. $100–$200) depending on the model. Additionally, each security code retrieval may carry a small per-use fee.

Q: How many keys can I program at once?

A: Usually up to 4 keys. After programming the first key, immediately follow the prompts to add a second key before exiting. If you exit too early, you can repeat the AKL process to add more later.

Q: Can I program a used/worn key to the GS4?

A: No. The transponder chip in a used key is already locked to the original ECU. You must use a new, blank chip. Even if the key is physically cut, the chip cannot be reused unless it is a rewritable type (rare on GAC vehicles).

Q: What if the X431 says "Vehicle Not Supported"?

A: Ensure you have the latest GAC software update installed. Some very early 2015 models may require a different protocol. Try selecting "GAC" → "GS4" and then choose "Automatic VIN" or "Manual VIN." If it still fails, contact LAUNCH support to verify compatibility with your specific VIN.

Q: Does this work for the GAC Trumpchi GS4 PHEV (Plug-in Hybrid) version?

A: Yes, but the procedure is nearly identical. The immobilizer control unit is usually located in the MGU (Motor Generator Unit) controller for PHEV models. The X431 will auto-detect this. Just follow the same steps.

Q: Is there a risk of bricking the ECU?

A: Risk is low with the X431 if you follow instructions. However, if you interrupt power during the "Erase" process (e.g., unplug the VCI or turn the ignition off), the ECU can become permanently locked. Always use a battery charger and disconnect only after the tool confirms completion.

Q: Can I use a smartphone or tablet app instead of the X431 tablet?

A: The X431 system includes a dedicated tablet (usually Android-based) with the LAUNCH app. You cannot use a generic smartphone—the app requires the official X431 VCI hardware and a licensed account.

Q: Where can I get a blank key for my Trumpchi GS4?

A: Purchase from automotive locksmiths, LAUNCH-authorized distributors, or online stores like Alibaba or local auto parts shops. Ensure you specify the model year and chip type (4D-60 or 46). You can also find pre-cut key blades if you provide the key code from the ignition lock.

Final Thoughts

The All-Keys-Lost procedure on a GAC Trumpchi GS4 is not a job for the faint-hearted, but with the LAUNCH X431, it becomes manageable. The key takeaways: prepare your tools, stabilize the battery, get the right transponder chip, and follow the on-screen instructions to the letter. If you run into trouble, most issues stem from voltage drops, wrong chip types, or incorrectly entered security codes. By addressing these variables upfront, you’ll have a smooth experience.

For more detailed guides on key programming and vehicle diagnostics, check out our article on [LAUNCH X431 immobilizer programming for Asian vehicles] . We also cover related topics like **[

All-Keys-Lost Programming: GAC Trumpchi GS4 with LAUNCH X431