The following soy milks do not contain any chometz ingredients:
Vitasoy San Sui Original Natural soy milk http://www.nasoya.com/ethnic/sansui_osd.html
Soy Dream Original un-enriched soy milk: http://www.tastethedream.com/products/product/1464/202.php
Anyone for whom it is necessary to consume kitniyos may drink these products. However, because we are unable to verify the kosher for Passover status of the equipment on which they are produced, we recommend purchasing these items before Passover, at which point any traces of chometz would be batul (nullified).
Another alternative would be to use a Kosher certified almond milk such as Blue Diamond Almond Breeze, which does not contain chametz and the kitniyot is batul (nullified).