The areas that vehicles can be detected in are outlined below.

To give the driver a more consistent time to react, the buzzer can alert for faster vehicles from farther away.
Example: 
The rear cross traffic alert function is operational when
Conditions under which the rear cross traffic alert function will not detect a vehicle
The rear cross traffic alert function is not designed to detect the following types of vehicles and/or objects.
*: Depending on conditions, detection of a vehicle and/or object may occur.
Conditions under which the rear cross traffic alert function may not function correctly
The rear cross traffic alert function may not detect vehicles correctly in the following conditions:

The rear cross traffic alert function
Driving tipsProblem symptoms table (2006/01- )
Hint:
Use the table below to help determine the cause of the
problem symptom. The potential causes of the symptoms
are listed in order of probability in the "suspected area"
column of the table. Check each symptom by checking the
suspected areas in the order they are listed. Re ...
Diagnostic trouble code chart
Hint:
Parameters listed in the chart may be different than your
readings depending on the type of instrument and other
factors.
If any dtcs are displayed during a check mode dtc check,
check the circuit for the dtcs listed in the table below. For
details of each dtc, refer to the page indica ...
Front door lock
Inspection
Inspect front door with motor lock assembly lh
Apply the battery voltage to the motor terminals and
check the operation of the door lock motor.
Ok
If the result is not as specified, replace the door lock
assembly.
Measure the resistance of the door lock position
...