Toyota PRIUS 2014 Manual page 558

5-2. Steps to take in an emergency
Warning message in radar cruise mode (if equipped)
■
In the following cases, the warning message may not be displayed even if
vehicle-to-vehicle distance decreases:
●
When your vehicle and the vehicle ahead are traveling at the same
speed or the vehicle ahead is traveling more quickly than your vehicle.
●
When the vehicle ahead is traveling at very low speed.
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Immediately after cruise control speed is set.
●
At the instant the accelerator pedal is depressed.
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PRIUS PHV_OM_OM47856U_(U)