To quote page 79 (in the 1999 Camry manual):
Daytime Running Light System
The headlights turn on at reduced intensity when the parking brake is released with the engine started, even with the light switch in the "Off" position. They will not go off until the ignition switch is turned off.
To turn on the other exterior lights and instrument panel lights, twist the [turn signal] knob to position 1 (your parking lights).
Twist the knob to position 2 to turn the headlights to full intensity for driving at night.
The headlights automatically turn to full intensity in the twilight even with the light switch in the "Off" position.
The daytime running light control sensor is on the top of the passenger's side instrument panel.
Do not place anything on the instrument panel, and/or do not affix anything on the windshield to block this sensor.
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So you
can turn your headlights on manually (as usual) but you've been waiting for the sensor to turn the lights on for you. It takes ten to fifteen seconds because, for example, if you were driving in a wooded area with sun shining through the trees, you don't want the lights to switch on and off and on and off. It has to make sure you're actually driving in low light before the lights turn on.
Hope this helped.
(edit: oh, and don't confuse "full intensity" with high beams. Your daytime running lights illuminate to about 90% as bright as the standard low beams; low beams being "full intensity".)