I got one for you, took the Vette (96LT-1) out for a ride, checked the temp 205* I glance down again and it says either SYS or 545 where the temp should be??? WTF?. Parked it for about 1-2 hours fired it up ran it for awhile, and everything is ok? Car runs great checked gauges all A-OK.

SYS... that means something has pissed off the CCM.

You can pull a code from the CCM, but I don't know the procedure for the 96... I will have to check the book.

Connect ALDL pins 4 and 12, it should start on the CCM module. This info should be in section 8 of Book 1 in the Genuine GM service manual.

OK now, just to clarify, it said 205* then it flashed SYS, in place of the temperature reading? then 205* then SYS???
Case, I've only got a Chiltons manual, just the bare bones info.
The car runs great, I just need to fix a small annoying exhaust leak.

SYS means there is a DTC present in the CCM module mate. It doesnt stay on solid if youve got it set to display coolant temp, it will swap between the 2.

You have to retrieve the DTC to find out what it is, and i doubt very much itll have much to do with how the car runs, cause its CCM and not PCM.

things that will set a CCM code? Low battery... something amiss with the IP, stereo or AC panel...

There are others, but they would also set PCM or EBCM codes.

No, a low battery will only cause a situation to set a DTC after start up when the battery voltage drops low, if its going on while the engine has been running that long, there is probably abit more to it than just a low battery. Could be anything. And i simply wont speculate til i see DTCs. I cant. Cause it really could be anything.