Passlock "relearn?"

[MikeHarrison]

The Body Control Module was replaced and the various issues (alarm sounding, door locks actuating, etc) have all ceased.

But I noticed that the Passlock warning lamp on the instrument cluster flashes when the car is parked/locked (so, I've been locking the car manually). When Googling this symptom, I see the phrase "passlock relearn." If this is what's required, is it something I can accomplish myself, easily?

Thanks.

[fdryer]

Yes, Passlock must be relearned when; ecm/pcm, bcm or ignition switch are replaced because each module shares a fuel password at factory assembly and a resistor embedded in the ignition switch must be learned. Dealers can program Passlock in 10 minutes using GMs Tech II scantool. Diyers can perform a Passlock relearn in 30 minutes without GMs scantool. The procedure is posted several times in these forums. When a bcm is replaced, mileage from the replacement is retained and cannot be changed, remotes are lost until GMs scantool or aftermarket scantool programs existing/replacement remotes (up to four) to the bcm. Ion remotes cannot be programmed without a scantool.

Basically, Passlock relearn requires turning on ignition, no start, for 10 minutes until the security light turns off, cycling ignition off and repeating this two more times. On the fourth try, startup should occur with Passlock security off. The fourth ignition cycle allows the bcm to learn the fuel password from the ecm/pcm or resistor value in the ignition switch. Passlock security resides in the bcm and controls the antitheft program.

Security has four modes; off (normally occurring when remotes Unlock/disables Passlock security, blinking once every few seconds as Passlock is armed when remotes Lock doors, flashing when attempting to start without remote Unlocking or damaging the ignition system, on when Passlock determines internal self tests fail and disables itself to allow normal startup - no antitheft protection.

[MikeHarrison]

Thank you. I need a bit more clarification, though.

Originally Posted by fdryer

Diyers can perform a Passlock relearn in 30 minutes without GMs scantool. ... Ion remotes cannot be programmed without a scantool.

I have an Ion. Does this mean a dealer has to do this relearn process? Thanks.

[fdryer]

You can do the Passlock relearn at home; three, 10 minute ignition on cycles. The fourth time, startup.

Remotes cannot be programmed. GM or aftermarket scantool can program remotes.

[MikeHarrison]

Thanks. By "remote," do you mean the key fob? Will doing the passlock relearn require the reprogramming of the remote so that everything works the way it had before replacing the BCM?

[fdryer]

Yes, remotes used here refer to key fobs. Same as remotes used for tv.

Passlock programming (GM describes it as a relearn procedure) when done at home, 'marries' three crucial parts with the 30 minute procedure - ignition switch, ecm/pcm and bcm when they're replaced. This does not program remotes.

GMs Tech II or aftermarket scantool (I use VCX NANO) programs remotes by interfacing thru the OBD II port to communicate to the bcm with commands. VCX NANO reads all GM error codes too.

[MikeHarrison]

OK, great. Thanks for that clarification. I was concerned because my remote does work with the new BCM.

My repair tech (he and his crew) are good people and in business at the same location since 1967. I'm sure they just forgot to do the relearn (they are equipped to program BCMs).

Thanks for the information. I really appreciate it.

[fdryer]

If they replaced the bcm, they probably programmed the remote.

[MikeHarrison]

Thank you!