Mechanic Wiki: GAC Trumpchi All-Keys-Lost Key Matching with LAUNCH X431 & 8-Digit PIN

Step-by-step guide to perform all-keys-lost key programming on a GAC Trumpchi using a LAUNCH X431 scanner and an 8-digit PIN. Includes troubleshooting, prerequisites, and FAQs.

Published: June 16, 2026

Quick Answer / Key Takeaway

To perform an all-keys-lost key matching on a GAC Trumpchi using a LAUNCH X431 and an 8‑digit PIN, you must connect the diagnostic tool to the OBD-II port, navigate to the immobilizer special functions, select "All Keys Lost," enter the correct security code, and program each new transponder key sequentially. The process erases all existing keys from the vehicle’s immobilizer memory, so you must program every key you intend to use in one session. If the PIN is rejected, verify the code source, update the LAUNCH X431 firmware, and confirm the vehicle model year supports 8‑digit PINs.

Introduction

Losing all keys to a GAC Trumpchi is a frustrating situation. Whether you misplaced the only set, the keys were stolen, or the immobilizer system suffered an electronic fault, the vehicle is effectively immobilized until new keys are matched to the security module. Unlike older vehicles where a locksmith could cut a mechanical key and start the engine, modern GAC Trumpchi models use a transponder-based immobilizer that requires a security handshake between the key chip and the Engine Control Unit (ECU).

This guide focuses on one of the most common and cost‑effective solutions: using a LAUNCH X431 diagnostic scanner with an 8‑digit security PIN. I’ll walk you through the entire procedure, from tool preparation to final testing, and cover the frequent issues that trip up even experienced technicians. By the end, you’ll understand exactly what to expect and how to avoid the typical pitfalls.

Prerequisites

Before you dive into the programming process, you need to have the right tools and information ready. Here’s a checklist:

Diagnostic Tool: A LAUNCH X431 model that supports GAC Trumpchi immobilizer functions (e.g., X431 PAD V, X431 PRO V, X431 EURO). Ensure the software is updated to the latest version – older firmware may lack the “All Keys Lost” option or fail to communicate with newer ECUs.
Security PIN: An 8‑digit numeric code. This can be obtained from a GAC dealer, a third‑party PIN service (calculating from the VIN), or from a previous working key if you had one. Do not proceed without a verified PIN – guessing will lock you out.
New Transponder Keys: Compatible with GAC Trumpchi. Most models use a Texas Instruments 4D chip (ID46 or ID4C) or a Philips 46/47 chip. Confirm with a key supplier or a chip reader. The key blank must also have the correct physical profile for the ignition lock cylinder.
Vehicle Condition: Battery voltage should be at least 12.5V. Low voltage can cause communication drops mid‑programming. Use a battery charger or power supply if necessary. The vehicle should be in a well‑ventilated area, ignition off initially.
Safety: Keep the ignition off except when instructed. Do not disconnect the scanner or turn off the ignition during programming – this can corrupt the immobilizer data.

Step‑by‑Step Procedure: All‑Keys‑Lost Key Matching

1. Prepare the LAUNCH X431

Connect the X431 to the OBD‑II port under the dashboard (driver’s side). Power on the tool and connect to Wi‑Fi. Update the diagnostic software by going to Settings → Software Update → GAC/Trumpchi. Download and install any available updates – this is critical because GAC frequently updates immobilizer algorithms. Once updated, select Diagnostics → GAC → Trumpchi → choose your specific model and year (e.g., Trumpchi GS4 2021). The tool will automatically detect the vehicle’s systems.

2. Access the Immobilizer System

From the system list, navigate to Special Functions or System Selection. Look for Immobilizer (IMMO) or Anti‑Theft System. Select it. The X431 will attempt to communicate with the immobilizer ECU. Wait for a confirmation message like “Communication Established.” If you get a “No Response” error, check the OBD connection and battery voltage.

3. Initiate All‑Keys‑Lost Programming

Inside the immobilizer menu, find Key Programming or Key Learning. Select All Keys Lost or Erase All Keys. The tool will display a warning: this action will permanently delete all existing key codes from the module. Confirm that you want to proceed. The scanner will then prompt you to enter the security PIN.

4. Enter the 8‑Digit PIN

When prompted, input the 8‑digit PIN using the on‑screen keypad. Double‑check each digit – a single wrong number will reject the code. Press Enter or OK. If the PIN is correct, the tool will proceed to the next step: “Insert the first key to be programmed.” If you see “PIN Invalid” or “Security Access Denied,” do not keep retrying. Stop and troubleshoot (see the Troubleshooting section below). After three consecutive wrong attempts, some immobilizer ECUs lock the tool out for a period (often 10–30 minutes).

5. Program the First New Key

Insert the new transponder key into the ignition. Turn the key to the ON position (engine off) – do not turn to ACC. The dashboard lights should illuminate. The tool will display something like “Learning Key 1, please wait…”. Wait 10–30 seconds. The scanner may emit a beep or show “Key 1 Learned Successfully.” If it fails, the key chip may be incompatible or the key may not be in the correct position.

6. Program Additional Keys

If you need more than one key, follow the on‑screen instructions: remove the first key, insert the next new key, turn to ON, and wait. Repeat until all keys are learned. The X431 will usually allow up to 8 keys per session. Important: you must program all desired keys now. If you skip a key and later try to add it, you may have to repeat the entire “All Keys Lost” procedure.

7. Final Verification

After the last key is learned, turn the ignition off and remove the key. Wait 10 seconds, then insert each programmed key one at a time and start the engine. Each key should crank and start normally. Also test the remote lock/unlock buttons – if the key has a remote fob, it should be automatically learned during the immobilizer process. If the remote does not work, you may need to run a separate “Remote Key” function from the X431.

Troubleshooting Common Issues

PIN Not Accepted

This is the most common roadblock. First, verify that the 8‑digit PIN actually corresponds to your specific vehicle – a VIN mismatch or a leftover PIN from a different car will be rejected. Second, ensure your X431 firmware is up to date. GAC sometimes changes PIN formats between model years; for example, some 2013–2015 Trumpchi models use a 5‑digit code, while newer ones use 8 digits. If you only have a 5‑digit PIN, you cannot pad it with zeros to make 8 digits – you need the correct 8‑digit code. Third, check the PIN source: if you bought it from an online service, ask them to re‑verify the VIN. Finally, some vehicles require an additional security “login” sequence before accepting the PIN – the X431 should do this automatically, but if not, try entering the immobilizer menu again.

Communication Failures

If the X431 cannot connect to the immobilizer ECU, start with the basics: is the OBD‑II connector pushed firmly? Are any pins bent? Try a different diagnostic cable if available. Low battery voltage is a frequent culprit – below 11.5V, the immobilizer may not respond. Use a jump box or battery charger. Also, check that you selected the correct vehicle model – selecting a different Trumpchi variant can cause the tool to look for the wrong ECU.

Key Not Learned After Programming

If the programming appears to succeed but the key does not start the engine, the transponder chip type may be wrong. For example, using a 4C chip when the vehicle expects a 4D chip. Use a chip tester or consult your key supplier. Another common mistake: turning the key to ACC instead of ON. The immobilizer requires the full ON position to read the chip. Also, some Ford‑based GAC platforms (like the Trumpchi GS5) require you to hold the key in the ON position for a specific number of seconds – follow the X431’s on‑screen timer precisely.

“All Keys Lost” Option Missing

Rarely, the LAUNCH X431 may not show an explicit “All Keys Lost” button for your particular model. In that case, try the following workaround: use the “Add Key” function, which will add a new key while keeping existing ones. But since you have no existing keys, the newly added key will be the only one. Alternatively, look for “Erase All Keys” or “Reset Immobilizer.” If none are available, you may need to update the X431 software or use a different tool (e.g., Autel IM608).

FAQ

Q: Can I use a generic OBD2 tool instead of LAUNCH X431?
A: No – all‑keys‑lost on GAC Trumpchi requires a specialized tool with immobilizer support, like LAUNCH X431, Autel IM508/608, or dealer software. Generic code readers cannot program keys.

Q: Where do I get the 8‑digit PIN if the dealer won’t provide it?
A: Third‑party services can calculate the PIN from the VIN (e.g., online calculators, professional key programmers). Some LAUNCH X431 models can also retrieve the PIN if one working key exists (but not in all‑keys‑lost scenario).

Q: What if I only have a 5‑digit PIN?
A: Some earlier GAC Trumpchi models use a 5‑digit or 4‑digit code. Check the vehicle’s production date and consult the tool’s immobilizer menu – it may accept shorter codes. If the tool expects 8 digits, you will need the correct 8‑digit code.

Q: Can I use a cloned key instead of a new transponder?
A: Cloning (copying) a key requires a working original. In an all‑keys‑lost situation, you must program a new, unique transponder key into the vehicle’s immobilizer. Cloning may work for remote functions but not for engine start.

Q: Will programming a new key erase my remote fob functions?
A: Usually yes – all key learning includes both transponder and remote functions. After programming, you may need to teach the remote lock/unlock separately using the X431’s “Remote Key” function.

Q: How many keys can I program at once?
A: The GAC Trumpchi immobilizer typically stores up to 8 keys. When using “All Keys Lost,” you must program all desired keys in one session – leaving one out requires repeating the entire procedure.

Q: What if the engine starts but the immobilizer warning light stays on?
A: This indicates incomplete programming or a fault in the new key. Re‑program the key following the exact steps; if the light persists, the key chip may be defective or the ECU may need a reset.

Q: Does the LAUNCH X431 support remote start programming?
A: For remote start (if equipped), use the X431’s “Remote Programming” or “Key Fob” function after successful key matching. This is a separate step and not part of the immobilizer programming.

Q: Can I perform this procedure without the LAUNCH X431?
A: Only if you have an original dealer diagnostic tool (GAC SmartScan) or an equivalent aftermarket tool (Autel, Xtool) with GAC coverage. The X431 is one of the most popular and cost‑effective choices for this job.

Conclusion

Performing an all‑keys‑lost key matching on a GAC Trumpchi with a LAUNCH X431 and an 8‑digit PIN is a systematic process that any competent technician can handle – provided they have the correct PIN and up‑to‑date tool firmware. The most critical steps are verifying the PIN, selecting the right immobilizer function, and programming all keys in one uninterrupted session. Once completed, test every key immediately to confirm both engine start and remote functions. If you encounter roadblocks, the troubleshooting section above covers the most common issues.

For deeper dives into related topics, check out our guides on [link to related guide on transponder chip types] and [link to related guide on PIN retrieval services]. Understanding the nuances of each GAC model will save you time and frustration on the job.

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/