How the System Works
URPA comes on automatically when the shift lever is
moved into REVERSE (R) and the vehicle speed is less
than 3 mph (5 km/h). When the system turns on, the
three lights on the display will illuminate for one and a
half seconds to let you know that the system is
working. If your vehicle is moving in REVERSE (R) at a
speed greater than 3 mph (5 km/h), the red light will
ash to remind you that the system does not work at a
speed greater than 3 mph (5 km/h).
If an object is detected at a REVERSE (R) speed of
less than 3 mph (5 km/h), one of the following will occur:
Description English Metric
Amber light 5 ft 1.5 m
Amber/amber lights 40 in 1.0 m
Amber/amber/red lights &
continuous chime20 in 0.5 m
Amber/amber/red lights
ashing & continuous
chime1 ft 0.3 m
A chime will sound the rst time an object is detected
between 20 inches (0.5 m) and 5 feet (1.5 m) away.
URPA cannot detect objects that are above trunk level.
In order for the rear sensors to recognize an object,
it must be within detection range behind the vehicle.
When the System Does Not Seem to
Work Properly
The light may ash red when the vehicle is in
REVERSE (R), if the ultrasonic sensors are not kept
clean. So be sure to keep your rear bumper free of mud,
dirt, snow, ice and slush. Other conditions that may
affect system performance include things like the
vibrations from a jackhammer or the compression of air
brakes on a very large truck. If after cleaning the
rear bumper and then driving forward at least 15 mph
(25 km/h), the display continues to ash red, see
your dealer.
If a trailer was attached to your vehicle, or a bicycle or
an object was hanging out of your trunk during your
last drive cycle, the light may also ash red. The light will
continue to ash whenever in REVERSE (R) until
your vehicle is driven forward at least 15 mph (25 km/h)
without any obstructions behind the vehicle.
For cleaning instructions, seeWashing Your Vehicle on
page 5-98.
3-45
Engine Speci cations
Engine VIN Code Transmission Spark Plug Gap
3.6L HFV6 7 Automatic 0.044 inches (1.1 mm)
4.4L DOHC V8 (V-Series) D Automatic 0.040 inches (1.0 mm)
4.6L DOHC V8 A Automatic 0.040 inches (1.0 mm)
STS-V Engine Data
Engine Horsepower Torque Displacement Compression Ratio
4.4L V8 (LC3)440 hp (328 kW)
@ 6400 rpm430 lb ft (583 Nm)
@ 3600 rpm4.4L 9.0:1
5-117
