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 tipsData list / active test (2005/11-2006/01)
Read data list
Hint:
Using the intelligent tester's data list allows switch,
sensor, actuator and other item values to be read without
removing any parts. Reading the data list early in
troubleshooting is one way to save time.
Connect the intelligent tester (with can vim) to the
...
Removal
Drain engine coolant (see page co-6)
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove air cleaner cap (see page es-41 ...
Throttle actuator control motor circuit
Description
The throttle actuator is operated by the ecm and opens and closes the
throttle valve using gears.
The opening angle of the throttle valve is detected by the throttle position (tp)
sensor, which is mounted
on the throttle body. The tp sensor provides feedback to the ecm. This ...