I own a 2007 GMC Yukon 5.3L V8. The only modifications I've made thus far are the addition of a Pioneer Apple CarPlay head deck and a back-up camera in the back. Since I purchased the vehicle just over a year ago, I've constantly received the message "Service Park Assist" on my message display--even before I installed the new stereo and camera. I have a back-up camera but I want the sensors to work as well. I want to do this project myself (simply because I get great satisfaction from doing things myself) but I'm not sure if it'* the sensors that are bad or if there is some sort of relay that might be bad. Here'* what I've done thus far:

1. I checked the fuse to make sure it was good (it is).
2. I started the vehicle, engaged the parking brake, put the vehicle in reverse, and checked each sensor manually. I assume it operates in a similar fashion as SONAR, the individual sensors would vibrate. None of them vibrated.

With that being said, either all of the sensors are bad, or a relay is bad. I searched through the present threads but didn't find anything that matched my situation. Does anyone have any suggestions on how I can approach this? Should I just replace all of the sensors and see what happens next? Is there a relay that tends to become inoperable after time? If so, where might I find that?

Thank you in advance for your assistance!

Allen

Could have sworn I posted about this yesterday.....

First, you need a scan tool capable of reading "B" codes.......that will tell you if an individual sensor circuit is at fault.....

There are no relays, only the module......

When you use the the E-brake, that disables the Park Aid....

I know on PA'*, you could pull a flash code with the three lights near the back window(unfortunately I don't remember the procedure), but not sure if this is possible with the Yukon..... you probably need a Tech II scan tool for this.....

I didn't see anything posted specifically about this issue. In any event, thank you for your response. I do have a scan tool capable of reading "B" codes; however, the error I'm getting pertains generally to Park Assist. The code reader isn't the best.

If I'm understanding your reply correctly, all I have to do is replace the sensors and I should be good?

Thanks!

No, that is not what I said.....I said a code, specifically, a "B" or "U" code could point you in the right direction.....

Remember, in diagnosis, you don't always replace the the part the code is named after......for example, you could have a B code naming a specific sensor circuit, like the outside passenger sensor......that doesn't mean the sensor is bad, it means that there is something wrong in that circuit....which means it could be the sensor, the module, or the wiring in between the two......

I have a 2008 Yukon Denali XL. Service park assist was on when I bought it. Cannot turn it on and off with dash display and the button on the lower dash only flashes when pressed. Red light comes on pass rear interior so it would seem there is power to the system, but non of the sensors click in reverse or anything. I have replaced the outside two with no results. Cannot be sure which fuses to check although I have checked several. Everyone says different things about the fuses where they are, which control this system, etc. I am about to try my two new sensors in the two middle positions as I have been told the entire system will shut down if one sensor is out... That could explain this, but I sure would like to have a diagnostic mode like Cadillac had to narrow down which, if any, sensor is out. I also have heard way too much about resetting the system. Not sure what to try or believe or in what order. So... I would like to check fuses, find out which sensor(*) is out (remember none of them click or make any noise/ seem to have zero power), and would also appreciate a brief explanation of how the system may be reset.
Thank you in advance.
Ben