So I went to start my jeep that's been sitting for only 2 days and I have a CEL. I put my reader on it and it shows up " AT system" I've tried google but found nothing. What is the AT system?? Also I shut the engine off and fired it back up after a minute and the rpm's shot up past 2000 and slowly came back down.
I have a 1998 Cherokee with a 4.6 stroker, aw4 tranny.
I did the engine swap about 6 or 8 months ago.

 

Code number was ?

 

I am going to take a wild stab with the limited information and guess that the AT system is the Auto Transmission system. Talk about a vague trouble code, what type of code reader are you using? If it doesn't give you actual codes take it someplace that will read the codes for free. That will give you an actual code and make it easier for people to help you out. There are some very knowledgeable and helpful people here, and with the right information can have you fixed up in no time.

 

Cant remember the code reader brand but it usually shows a number. Tried it a couple of times but always showed "AT system".
I'm at work right now but will give more info when I get home.
What kind of info would help you guys diagnose this?
Thanks.

 

The code number would be the biggest help. It could be that your reader is not capable of reading TCU codes. I know that my reader can read them but wont reset them.

 

Best would be to try and get an actual trouble code. Try a different code reader or a scan tool.

Post the exact code here for comment.

 

Alright, gonna try a different code reader coz AT system means nothing to anyone. I'll see what I can do tonight.