All at once, if you have two cars from the same manufacturer, you might be able to consolidate and handle both cars with just one keyless entry. This is the key that controls this car. This one only controls the black car over there by the time. We’Re done this key fob should control both cars. The first step is to put the car into programming mode. Now every manufacturer is different, so you’ll need to look yours up online to see if this will work, but for this model we cycle the power four times, and you hear a tone indicating it’s ready to receive key fobs. We press one for each of the keys.