According to the manual -
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How the System Works when Backing
If the shift lever is in REVERSE (R), URPA detects objects close to the rear bumper. The first time an object is detected a single beep will sound. If an object is detected at a REVERSE (R) speed between 0 mph and 5 mph, the following describes what will occur based on your distance to a detected object located behind the vehicle:
• At distances between 40 inches and 8 ft, a single amber light will come on.
• At distances between 23 inches and 40 inches, both amber lights will be on.
• At distances between 12 inches and 23 inches, all three lights (amber/amber/red) will be on.
• At distances less than 12 inches, a beeping sound will repeat for a short time and all three lights (amber/amber/red) will flash.
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I would assume that is the same across the board for all GMT900 vehicles. I hope that helps!
