First time to post on a forum, thank you in advance for any help! I own a 2008 Suburban LTZ. I replaced the rear bumper, the park assist harness, and sensors. The old one was held together with wire nuts and mismatched sensors, but it worked. The new setup works in reverse but when I drive 8-10mph I get the “service park assist” message on the DIC. I’ve had a mechanic friend use his shops scanner and clear all the codes. I’ve removed the positive terminal on my battery and took out the fuse (#20 on the inside panel). I’ve removed the negative cable for an hour. I’ve searched forums for hours. One guy posted here about 10 years ago with the same issue but did not say if or how it got resolved.

Anyone have an idea? I wonder if it’s the park assist module, but everything worked fine when I took the bumper off a few days ago. Again, the system works as it should in reverse. It’s when I drive forward that I get the code. It will turn off and back on seemingly at random when I drive.

 

What were the codes? They are there to tell you what's wrong.
Clearing trouble codes is like shooting the messenger. The Mongols are still invading.

 

The codes were “sensors 2, 3, 4 short to battery.”

 

I read elsewhere that someone else had the same problem - all worked in reverse, sensors 2, 3, 4 had shorts to battery in drive. Turns out the new harness with new sensors had three faulty sensors! I’ve read not to buy the cheap ones, lesson learned. Ironically, I swapped those three sensors with my old ones, which are also cheap replacements, and the problem seems to be gone. Guess you take your chances with cheap replacements.