Passlock III reset procedure

How to do a Passlock III reset

If you own a General Motors (GM) vehicle with the Passlock III system and are

Passlock III transponder keys are identified by the PK3 mark on the shank

dealing with a no-start issue, you’re likely facing an anti-theft system lockout. The Passlock III reset process can get your car running again without a costly trip to the dealership. I’ve performed numerous Passlock reset procedures on different GM models, and I can tell you firsthand that understanding how the Passlock III reset works is critical to fixing the problem.

GM made several different types of anti-theft

systems. VATS, PassKey, and PassLock. The troubleshoot and reset procedures are different for each. PassLock seems to have the highest failure rate. So if you have a key WITHOUT a chip in it, chances are it’s a PassLock system. This article describes how to troubleshoot and fix a PassLock system. But here are some more articles to help.

When You Need a Passlock III Reset

You’ll know you need a Passlock reset if you experience the following symptoms:

• The security light on the dashboard stays on or flashes after turning the key.
• The engine cranks but doesn’t start because the fuel injectors are disabled.
• The vehicle starts for a few seconds and then shuts off.
• You recently replaced the key, battery, or ignition switch, which can trigger the system to think it’s under attack.

If any of these sound familiar, then it’s time to perform a Passlock III reset to reprogram the system and get back on the road.

Step-by-Step Passlock III Reset Procedure

Make sure the battery if fully charged because this procedure may take up to 30 minutes and you cannot start the vehicle during this time. If you’re adding a new key to the system, you MUST have all the older keys with you. All previously learned keys will be erased from the system as soon as you program the first key. After the first key has been relearned, immediately insert the next key to be programmed within 10 seconds.

1. Insert the master key with the black head into the ignition lock cylinder
2. Turn the key to ON but do not start the engine. The SECURITY light will turn on and stay on.
3. Wait 10 minutes or until the SECURITY light to turn off.
4. Turn the key to OFF for 5 seconds.
5. Turn the key to ON but do not start the engine. The SECURITY light will turn on and stay on.
6. Wait 10 minutes or until the SECURITY light to turn off.
7. Turn the key to OFF for 5 seconds.
8. Turn the key to ON but do not start the engine. The SECURITY light will turn on and stay on.
9. Wait 10 minutes or until the SECURITY light to turn off.
10. Turn the key to OFF. The key transponder will be learned on the next start cycle.
11. Start the vehicle. If it starts and runs normally, the relearn is complete. If you need to program additional keys,
12. Turn the key to OFF.
13. Insert the next key. Turn it to ON within 10 seconds of removing the previously used key.
14. Wait for the SECURITY light to turn off. That may happen quickly. You may not even notice it.
15. Repeat steps 12 through 14 for all additional keys.

Additional Troubleshooting for Passlock III Issues

If your car still won’t start after the Passlock III reset, consider these additional steps:

• Check the key: If you have a spare key, try it. Sometimes, the transponder inside the key stops working.
• Inspect the ignition switch: A worn or damaged ignition cylinder can fail to communicate properly with the Passlock III system.
• Scan for codes: If you have access to a GM-compatible scan tool, check for stored security system codes.
• Disconnect the battery: Remove both battery terminals and hold them together for 10 seconds to reset all modules, then reconnect and attempt the Passlock reset again.

Preventing Future Passlock III Reset Issues

After successfully performing a Passlock III reset, you don’t want to run into the same problem again. Here are some tips to avoid future issues:

• Use a GM-original key: Cheap aftermarket keys might not have the correct transponder.
• Keep your battery in good shape: A weak battery can cause the security system to glitch.
• Don’t rush the ignition cycle: Give the system a second to recognize the key before cranking.
• Avoid replacing the ignition switch unless necessary: If you do, be prepared to perform a full Passlock III reset.

How Passlock III Differs from Previous Versions

GM introduced the Passlock system to prevent theft by disabling the fuel injectors if the ignition switch was turned without the correct key. However, earlier versions of Passlock (I and II) had a major flaw: they relied on a simple sensor inside the ignition cylinder that could fail and trigger false security lockouts.

Passlock III took it a step further by integrating a transponder chip inside the key itself. Unlike the earlier systems that only relied on resistance readings from the ignition, Passlock III requires both the correct key and a properly programmed transponder to allow the vehicle to start. This means that if the transponder or the key loses synchronization with the system, you’ll be stuck with a Passlock III reset situation.

Click here to see the resetting procedure for PassLock

Click here to see the trouble codes for a PassLock system

Click here to see a typical PassLock wiring diagram

IF you have a PassKEY system, click here to see the reset procedure

© 2012 Rick Muscoplat