8-40 Driving and OperatingTurning the System On and OffThe UFRPA system can be turnedon and off by pressing the parkassist button located next to theshift lever.The park assist button lights upwhen the system is on and turns offwhen it has been disabled.When the System Does NotSeem to Work ProperlyIf UFRPA does not turn on due to atemporary condition, the messagePARK ASSIST OFF displays on theDIC, and the light on the park assistbutton turns off. This can occurunder the following conditions:. The ultrasonic sensors are notclean. Keep the vehicle'sbumpers free of mud, dirt, snow,ice and slush. For cleaninginstructions, see Exterior Careon page 9‑109.. A trailer was attached to thevehicle, or an object washanging out of the liftgate duringthe last drive cycle. Once theattached object is removed,UFRPA will return to normaloperation.. If an object is attached to thefront of the vehicle.. A tow bar is attached to thevehicle.. The vehicle's bumper isdamaged. Take the vehicle toyour dealer/retailer to repair thesystem.. Other conditions may affectsystem performance, such asvibrations from a jackhammer orthe compression of air brakes ona very large truck.If the system is still disabled, afterdriving forward at least 25 km/h(15 mph), take the vehicle to yourdealer/retailer.