This morning it as pretty cold, in the 20's, and after using the remote start to let my SRT8 warm up, I got a strange message on the dash info center. After driving maybe a half mile from my house, while making a sharp left turn, the GC made that "look at me" tone and the information display said to "Service Park System", it beeped 3 times, then the message went away.

Anyone get this before? It happened right when I made a sharp left turn. Not sure if that has anything to do with it...

I think this is related to the back up sensors. Could there have been ice or snow blocking the back-up sensors on the rear bumper? I could be wrong, just guessing here.

No ice/snow. Maybe some condensation from morning dew, but it was in the 20's so there may have been some frost.

Last Wed when it rained hard, my park assist was acting up all day, and I got the message everytime I started the car. The next day, not one problem. Besides the message, the lights on the rear roof were going crazy....still no problem. Dealer told me to bring the car in next time it is doing as, as it does not store a code.

Mine has been in the shop for the last nine days. One of the symptoms was this park assist message. My problem has been attributed to a malfunctioning computer that sends and recieves messages from the alternator. I hope this is not your issue, but if this and/or other messages like this continue you may want to look there.

Mine has been in the shop for the last nine days. One of the symptoms was this park assist message. My problem has been attributed to a malfunctioning computer that sends and recieves messages from the alternator. I hope this is not your issue, but if this and/or other messages like this continue you may want to look there.

9 days? Sorry to hear that. It may be easier tell them to just disable the rear park assist. Not sure how the alternator would play into it, but anything is possible. Funny though mine just acted up in the rain. Since it does not store a hard code, only God knows, and he is not talking.

No ice/snow. Maybe some condensation from morning dew, but it was in the 20's so there may have been some frost.
Frost could cause the warning message you are getting, see if it happens again and go from there. There are codes that are stored for some malfunctions so that could be checked if it keeps happening. It's important that they are kept clean.

According to the dealer, no code is stored for the park assist.

I had the same message come up on mine last week when it was below -40 Celsius with the windchill...brrrr and there was some frozen snow/ice on the rear bumper. The message is gone now and so is the cold weather. Knock on wood.

According to the dealer, no code is stored for the park assist.
From a TSB for 2005 Grand Cherokee models:

Verify if one or more of the following Park Assist Diagnostic Trouble Codes (DTC) are present:

• B122F - PTS Sensor 7 Ring Time Too Long.
• B1234 - PTS Sensor 8 Ring Time Too Long.
• B1239 - PTS Sensor 9 Ring Time Too Long.
• B123E - PTS Sensor 10 Ring Time Too Long.

If one or more of the above Park Assist system related DTC's have occurred and the rear sensors are known to be free of debris, snow, and ice when the condition occurs, then perform the Repair Procedure.

mine did it this morning too also low 20's but it's coved in salt that is probably my problem.