GM VATS / Passlock Security Relearn Procedure | 30-Minute Relearn

The 30-minute relearn teaches your GM's security system a new key code or resyncs the PCM after a module swap. It is a free, no-tool procedure — but only on the right vehicles. Confirm yours is on the list below before you spend half an hour on it.

Does this procedure apply to my vehicle?

Before you start

• Put a battery charger or maintainer on the vehicle. The ignition sits in the ON position for 30 minutes with no alternator output — a marginal battery will drop voltage and fail the relearn.
• Have every key you want to use in hand. This procedure erases all previously learned keys. Any key not relearned afterward stops working.
• Turn off or unplug aftermarket remote start and alarm modules if you have them. A bypass module that fires mid-procedure will corrupt the learn.
• Pull the key all the way to OFF between cycles, not ACC.

The relearn, step by step

1. Insert the master key (black head) into the ignition.
2. Turn the key to ON without starting the engine. The security light comes on and stays on.
3. Wait 10 minutes, or until the security light goes out.
4. Turn the key OFF for 5 seconds.
5. Turn the key to ON without starting. The security light comes on and stays on.
6. Wait 10 minutes, or until the security light goes out.
7. Turn the key OFF for 5 seconds.
8. Turn the key to ON without starting. The security light comes on and stays on.
9. Wait 10 minutes, or until the security light goes out.
10. Turn the key OFF. The key code is written on the next start cycle.
11. Start the engine. If it starts and runs normally, the relearn is done.

Adding your remaining keys

1. Turn the key OFF and remove it.
2. Insert the next key and turn it to ON within 10 seconds of pulling the last one.
3. Wait for the security light to go out. This happens almost immediately — you may not see the light change at all.
4. Repeat for each additional key.

When it doesn't take

The security light goes out after a few seconds instead of staying on

The system never entered learn mode. Usually the ignition wasn't taken fully to OFF between cycles, or the OFF period was shorter than 5 seconds. Start the whole procedure over.

The light never goes out, even past 15 minutes

Suspect the Passlock sensor in the ignition lock cylinder or its wiring — a known failure point on GMT800 trucks and W-body cars. The three-wire Passlock circuit at the column is worth checking before you condemn the BCM.

It relearns, then the light comes back a day later

An intermittent Passlock sensor or a chafed harness at the column. The relearn masked it temporarily; the fault is still there.

Codes you may find