I had the same issue with the TCS. It would intemittently ding and the light would illuminate and remain on while driving. Or would come on when the vehicle was started. Sometimes my cruise would not engage, or it would disengage if I had it engaged.
After a engine off/restart the light would almost always illuminate and disappear like it should. I was going to bring it in at my next oil change interval except one day I had the TCS, ESP, ABS, and the check engine light come on. I took it in the next day and they said that it was a sensor that monitors my braking. They told me that as far as the Jeep was concerned, I didn't have any brakes, so it could not use any of the systems.
Apparently this was the intermittent cause for my cruise not working, and apparently I didn't have any brake lights either because it didn't know I was braking. The part and labour cost me about $170CDN
I also had an issue, about 30,000km's earlier where the "serv4wd" light would come on for me intermittently and I took the vehicle to the dealer numerous times. Whenever they would go out the light wouldn't come on for them and they said there was no codes stored.
Finally one day it happened while I was driving by so I dropped in and left the engine running. They wound up replacing a sensor in the transfer case. The system was apparently engaging and disengaging normally even when it was saying there was a fault, and you could hear it working, but something weird was happening and it thought something was wrong.
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