How do you reprogram a remote for a toyota sienna

Yes it does, and programmable fob

https://www.carandtruckremotes.com/1998toyotasiennakey.html

Program Remote
PRESS the LOCK and UNLOCK buttons on the remote simultaneously for 1 second. b. PRESS and HOLD the LOCK button for 2 seconds. The Door Locks will cycle LOCK/UNLOCK to indicate successful programming of the remote.
1998 Toyota Sienna Keyless Entry Remote Fob Programming ...

https://www.google.com/search?q=98+toyota+sienna+transponder+key+programming

..

The vieeo should provide the answer you need.
Toyota Keyless Entry Remote Replacement Programming Corolla Camry...

Hi found this link when researching your post , it would appear the 2004 sienna has to go to a dealer to be programmed , follow this link and see what you think about it
Toyota Transponder key programing

remote key need diagnostic equipment to reprogram key.

You have to go to a toyota dealer service centre to program the remote. But I am sure you are well aware of that.

May be keyfob needs reprogramming.

Keyfob remote reprogramming is not very difficult but on some cases it can be done by dealer service tools.

If the remote s faulty then key fob will not get programmed.

Insert the key in ignition. Turn the key to on position, and cycle the key three times off-on-off-on-off-on. Then with the key fob remote select your remote and then try to operate the vehicle with remote.

These are just the basic procedure, but sometimes it will not help.

On that case dealer is the only option.

---------

There are few much related troubleshooting links mentioned below for remote key fob reprogramming. I suggest you to go through the list and click the link below to go through its details and procedure: -------

Theft indicator not letting car to start?

http://technoanswers.blogspot.in/2012/02/theft-indicator-not-letting-car-to.html

-------------

2009 Toyota Highlander: Smart Key Not getting Detected?

http://whatisbyme.blogspot.in/2012/05/2009-toyota-highlander-smart-key-not.html

----------

2007 Toyota Prius: Reprogram Remote Keyfob?

http://whatisbyme.blogspot.in/2012/05/2007-toyota-prius-reprogram-remote.html

-----------

Pin that holds the flick key part to the key fob?

http://whoisbyme.blogspot.in/2012/07/pin-that-holds-flick-key-part-to-key-fob.html

-------------

2006 Toyota Hilux: Programming New Key?

http://technoanswers.blogspot.in/2012/04/2006-toyota-hilux-programming-new-key.html

----------

Where is Key chip memory located on 2004 ford Freestar?

http://technoanswers.blogspot.com/2012/01/where-is-key-chip-memory-located-on.html

----------

Ford Keyless Remote Fob Reprogramming?

http://schematicsdiagram.blogspot.com/2011/12/ford-keyless-remote-fob-reprogramming.html

----------

After getting car washed, check engine light is ON and key less entry not working, tried reprogramming. Also car shows fuel pressure?

http://schematicsdiagram.blogspot.com/2011/12/after-getting-car-washedcheck-engine.html

-----------

Audi A8 Key Fob Programming?

http://technoanswers.blogspot.com/2011/12/audi-a8-key-fob-programming.html

----------------

Oldsmobile Aurora Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/olds-aurora-key-fob-reprogramming.html

-------------

Buick Lesabre Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/buick-lesabre-key-fob-reprogramming.html

---------------

Keyfob remote not working on 2003 Ford E350 Econoline?

http://technoanswers.blogspot.in/2012/01/keyfob-remote-not-working-on-2003-ford.html

-----------

KeyFob will open the doors but not start on BMW?

http://technoanswers.blogspot.in/2012/02/key-will-open-doors-but-not-start-on.html

------------

Mitsubishi Car Key Not getting detected after replacing ECM

http://repairhelpcenter.blogspot.com/2012/11/mitsubishi-car-key-not-getting-detected.html

-----------

Key Fob will not lock and unlock doors?

http://technoanswers.blogspot.in/2012/02/key-fob-will-not-lock-and-unlock-doors.html

-------------

2000 Jeep Cherokee Limited: KeyFob Remote Not Working?

http://schematicsdiagram.blogspot.in/2012/06/2000-jeep-cherokee-limited-keyfob.html

-----------

Chevrolet Malibu: Key Stuck in ON position?

http://technoanswers.blogspot.in/2012/04/chevrolet-malibukey-stuck-in-on.html

-----------

2012 Dodge Ram: Ignition Key will not release?

http://whoisbyme.blogspot.in/2012/07/2012-dodge-ram-ignition-key-will-not.html

--------------

These details will help.

Thanks.

Try with brand new key fob battery and see.If that helps.
Otherwise May be keyfob needs to be reprogrammed.

KEYFOB PROGRAMMING

Keyfob remote reprogramming is not very difficult but on some cases it can be done by dealer service tools.

If the remote s faulty then key fob will not get programmed.

Insert the key in ignition. Turn the key to on position, and cycle the key three times off-on-off-on-off-on. Then with the key fob remote select your remote and then try to operate the vehicle with remote.

These are just the basic procedure, but sometimes it will not help.

On that case dealer is the only option.

---------

There are few much related troubleshooting links mentioned below for remote key fob reprogramming. I suggest you to go through the list and click the link below to go through its details and procedure: -------

2009 Toyota Highlander: Smart Key Not getting Detected?

http://whatisbyme.blogspot.in/2012/05/2009-toyota-highlander-smart-key-not.html

----------

2007 Toyota Prius: Reprogram Remote Keyfob?

http://whatisbyme.blogspot.in/2012/05/2007-toyota-prius-reprogram-remote.html

-----------

Pin that holds the flick key part to the key fob?

http://whoisbyme.blogspot.in/2012/07/pin-that-holds-flick-key-part-to-key-fob.html

-------------

2006 Toyota Hilux: Programming New Key?

http://technoanswers.blogspot.in/2012/04/2006-toyota-hilux-programming-new-key.html

----------

Where is Key chip memory located on 2004 ford Freestar?

http://technoanswers.blogspot.com/2012/01/where-is-key-chip-memory-located-on.html

----------

Ford Keyless Remote Fob Reprogramming?

http://schematicsdiagram.blogspot.com/2011/12/ford-keyless-remote-fob-reprogramming.html

----------

After getting car washed, check engine light is ON and key less entry not working, tried reprogramming. Also car shows fuel pressure?

http://schematicsdiagram.blogspot.com/2011/12/after-getting-car-washedcheck-engine.html

-----------

Audi A8 Key Fob Programming?

http://technoanswers.blogspot.com/2011/12/audi-a8-key-fob-programming.html

----------------

Oldsmobile Aurora Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/olds-aurora-key-fob-reprogramming.html

-------------

Buick Lesabre Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/buick-lesabre-key-fob-reprogramming.html

---------------

Keyfob remote not working on 2003 Ford E350 Econoline?

http://technoanswers.blogspot.in/2012/01/keyfob-remote-not-working-on-2003-ford.html

-----------

KeyFob will open the doors but not start on BMW?

http://technoanswers.blogspot.in/2012/02/key-will-open-doors-but-not-start-on.html

------------

Mitsubishi Car Key Not getting detected after replacing ECM

http://repairhelpcenter.blogspot.com/2012/11/mitsubishi-car-key-not-getting-detected.html

-----------

Key Fob will not lock and unlock doors?

http://technoanswers.blogspot.in/2012/02/key-fob-will-not-lock-and-unlock-doors.html

-------------

2000 Jeep Cherokee Limited: KeyFob Remote Not Working?

http://schematicsdiagram.blogspot.in/2012/06/2000-jeep-cherokee-limited-keyfob.html

-----------

Chevrolet Malibu: Key Stuck in ON position?

http://technoanswers.blogspot.in/2012/04/chevrolet-malibukey-stuck-in-on.html

-----------

Theft indicator not letting car to start?

http://technoanswers.blogspot.in/2012/02/theft-indicator-not-letting-car-to.html

-------------

2012 Dodge Ram: Ignition Key will not release?

http://whoisbyme.blogspot.in/2012/07/2012-dodge-ram-ignition-key-will-not.html

--------------

These details will help.

Thanks.

Keyfob remote reprogramming is not very difficult but on some cases it can be done by dealer service tools.If the remote s faulty then keyfob will not get programmed.Insert the key in ignition.Turn the key to on position,and cycle the key three times off-on-off-on-off-on.Then with the keyfob remote select your remote and then try to operate the vehicle with remote.These is just the basic procedure,but sometimes it will not help.
On that case dealer is the only option.
---------There are few very relted troubleshooting links mentioned below for remote key fob reprogramming.I suggest you to go through the list and click the link below to go through its details and procedure:-------
2009 Toyota Highlander: Smart Key Not getting Detected? http://whatisbyme.blogspot.in/2012/05/2009-toyota-highlander-smart-key-not.html
----------2007 Toyota Prius: Reprogram Remote Keyfob? http://whatisbyme.blogspot.in/2012/05/2007-toyota-prius-reprogram-remote.html
----------- Pin that holds the flick key part to the key fob? http://whoisbyme.blogspot.in/2012/07/pin-that-holds-flick-key-part-to-key-fob.html
-------------
2006 Toyota Hilux: Programming New Key? http://technoanswers.blogspot.in/2012/04/2006-toyota-hilux-programming-new-key.html
----------Where is Key chip memory located on 2004 ford Freestar? http://technoanswers.blogspot.com/2012/01/where-is-key-chip-memory-located-on.html
----------Ford Keyless Remote Fob Reprogramming?

http://schematicsdiagram.blogspot.com/2011/12/ford-keyless-remote-fob-reprogramming.html
----------After getting car washed, check engine light is ON and key less entry not working, tried reprogramming. Also car shows fuel pressure? http://schematicsdiagram.blogspot.com/2011/12/after-getting-car-washedcheck-engine.html
-----------Audi A8 Key Fob Programming?

http://technoanswers.blogspot.com/2011/12/audi-a8-key-fob-programming.html

----------------
Oldsmobile Aurora Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/olds-aurora-key-fob-reprogramming.html

-------------
Buick Lesabre Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/buick-lesabre-key-fob-reprogramming.html

---------------
Keyfob remote not working on 2003 Ford E350 Econoline?

http://technoanswers.blogspot.in/2012/01/keyfob-remote-not-working-on-2003-ford.html

-----------
KeyFob will open the doors but not start on BMW?

http://technoanswers.blogspot.in/2012/02/key-will-open-doors-but-not-start-on.html

------------
Mitsubishi Car Key Not getting detected after replacing ECM http://repairhelpcenter.blogspot.com/2012/11/mitsubishi-car-key-not-getting-detected.html
----------- Key Fob will not lock and unlock doors?

http://technoanswers.blogspot.in/2012/02/key-fob-will-not-lock-and-unlock-doors.html

-------------
2000 Jeep Cherokee Limited: KeyFob Remote Not Working? http://schematicsdiagram.blogspot.in/2012/06/2000-jeep-cherokee-limited-keyfob.html
----------- Chevrolet Malibu: Key Stuck in ON position? http://technoanswers.blogspot.in/2012/04/chevrolet-malibukey-stuck-in-on.html
----------- Theft indicator not letting car to start?

http://technoanswers.blogspot.in/2012/02/theft-indicator-not-letting-car-to.html

-------------
2012 Dodge Ram: Ignition Key will not release? http://whoisbyme.blogspot.in/2012/07/2012-dodge-ram-ignition-key-will-not.html
--------------
These details will help.Thanks.

System memory may have been erased/lost due to extended loss of power. System may have to be reprogrammed to effectively work. Do you have the programming CD? If so, check owners manual for programming procedures

The old remote can be programmed again but you need to take the remotes to be programmed together. They must be programmed at the same time and I believe you can program up to 4 remotes per vehicle. I think the venture requires a scan tool for reprogramming. Try this first- 1. Sit in the drivers seat and put the key in the ignition in the off position. 2. With your left hand hold down the unlock button on the door panel and turn the key to the on (not the run position) then off, then on and off. 3. If the horn honks, take one remote and hold down the lock and unlock buttons until the doors lock and unlock, then do the same for the second remote. 4. Now, turn the key to the on position, then off position and the horn should sound again. Try unlocking/locking the car with each remote. **step 2 may require the key to be turned on then off 3 times instead of 2 before the horn honks. This my not work but if it fails it will not change any of the current settings but you will need to have the dealer program the remotes together.