Hi all , have a 97 4.0 grand , I know this is xj section but same engines and looking for answers quick. Started having random shut downs.no work done recently, jeep runs fine ATM, will just cut out random. So far restarted fine and drove like normal. Only showing code 12 when read from dash .
Last time it shut down actually turned over but did not start first try but did on second . And again ran fine after.
Any ideas ? Hitting brick wall here, I've had it running and wiggled everything under the hood but it keeps running 🤦🏼‍♂️

 

Code 12= Battery has been disconnected in last 50 starts.
Usually means battery has been disconnected, loose or bad terminals, or ground connections. I don't suspect that is the cause of the problem your describing, It sounds like a CPS.

 

What he said. Put a real code scanner on it.

 

Hi, that's what I'm a bit annoyed about, battery has not been disconnected, slowly going through grounds when I get time and clean them up. . . I have a spare cam sensor here I will try too . I have a spare crank sensor too but my experience is the crank sensor will make it run bad but not cut out .

 

Bad CPS cutting out engine specially when warm, is a common problem on the 4.0 inline 6 engines.

 

The lack of a 55 at the end of the codes is concerning. It should blink 55 every time. This could be the result of a ECU going bad. See if you can get an OBD reader and check what you can.

 

Whenever you get your vehicle into a no start try checking it for spark and if you have a fuel pressure tester handy it wouldn't hurt to try that out as well. If you are missing either one of those you got a little more testing you got to do.

 

My bad yes I always have 55 , reason I ignored it , appreciate the help 👌

 

Hi, 100% what I'm thinking, intermittent problems are the worst . If it just sat not working I could work through it 🤣

 

Cut out three times one trip today - not warm and early morning, then nothing - ran fine coming home .

Ordered coil cap and rotor , cheap and tbh it can only help . I've swapped out relays , checked connectors , wobbled everything . Nothing is appearing to be bad

 

Is your CEL on? Get a real code reader and report the codes.

 

Im still inclined that its the CPS

 

No it is not, I've great results using the odometer readout / ignition key flick for reading codes so far ! Last two days no stall !

 

You could still be right but after many more starts and small trips over two days I've had no problems, I did lots of reading and spent time around the PDC, unplugging and plugging everything effectively cleaning contacts, also right near the PDC is a connector in the loom which looked dirty as hell, opened it up, looked ok inside but you never know. Anyways since that time it hasn't stalled. I'll give it a bit longer before I decide that I've fixed it !