Adding an additional remote to a 2004 Tundra Double Cab

Could be a pain in the ass, may not work. Willing to take a chance?

You need to disconnect the negative (maybe even the positive) terminal of the battery for quite a while, 10 minutes or more. This will blank *all* the electronics in the vehicle (computer, radio, alarm, etc) radio seettings will be gone, clock reset, etc.

Go have a Crown and coke while waiting...er wait till later, perhaps...

Reconnect the positive, reconnect the negative. Push the door lock button on remote #1 and then *immediately* on remote #2. This should reprogram the system to recognize bot remotes.

If you can locate the fuses/connectors to the alamr/door lock itself, disconnect these. But sometimes there are unmarked 'backups' so that if someone breaks in and tries to disable the system, it doesn't . That's why I suggest removing both battery cables.

You may want to call Toyota (delaer/service) and ask them if this works. If you bought it at a dealer, call them. They may require you to come in with ID, etc before divulging such information. Just like keys.