2007 suburban

I get a message no (backup assist off) the light is on the panel under the radio and at the back of truck I have just the one red light. How can I check the system to see which sensors is bad. Thank You

You need to have the codes checked, if its a sensor problem (probably is) there are specific codes for each sensor. The bumper cover needs to come off to access the sensors and plugs. Also, they do not come painted. Don't try and use touch-up paint to do it yourself, if the paint coat is too thick the sensor will not work, or work incorrectly. Don't lose the rubber seal around the sensor either, it must be reinstalled.

Thank you for the reply,I used a actron obd scanner to check for codes but did not get a code fault. Maybe I will try to check at the sensors to see if there is an open in the wiring again thank you.

Unless your OBDII scanner can access the Park Assist Module, which I doubt, you wont be able to see the codes. You will need to go to a dealer or find someone with a GM TechII scanner to read the codes.