This will also be my member introduction. First post here at Cherokee Forums. From southwest Ohio. I got an issue here with a 1998 Cherokee (4.0) i purchased about 2 months ago. Electrical is not my specialty and I am a novice mechanic at best. There's a few different things going on here that seem to be correlated so i will start at the beginning.

1. I do seem to have a late or lazy start. I have to hold the key in for a bit longer than usual to get it to start. ONly seems to be doing this if it has set for awhile.

2. This next issues pops up randomly. My tac will start going hay wire, and it will feel as though I am not getting continuous power, like a bad battery connection. When i first noticed this i cleaned the terminals and it went away for awhile. It came back, this time check engine light came on (explained next in #3) So for hell of it i put on brand new terminals and it seemed to be running great all that day and evening. Next day i got a real lazy crank, and the problem was back, shooting the same codes.

Now i did notice that taking the ground off the battery and resetting the computer seems to make the problem go away for awhile. But Seems to come back if car has sat for awhile. Sometimes when this issue comes, it has gone away once i really got on the gas, but not always.

3. Here are the codes that pop up when check engine light does come on:

P1391
Definition: CMP or CKP signal intermittent condition
Explanation: ECM detected actual CMP position disagreed with expected CMP level
Probable Cause: a) Timing belt stretched or jumped b) Defective CMP sensor


P1698
Definition: ECM Fault - no message from TCM
Explanation: Failed ECM
Probable Cause: a) Open CCD bus line b) Failed TCM


And like i said, if i re set the computer, it seems to go away. Sometimes if I just keep driving it will go away, but check engine light wont go off if i do that. But so far it has always come back after a day or so. I can tell you that the ground wire from the battery does appear to be very corroded. When i stripped it down to put the new terminal on it was corroded as far as i stripped it back and could tell it went on. The battery is dated 6/09 and probably sat for awhile before i purchased the jeep.

Any input on this would be helpful. Keep in mind, I am a rookie and my technical knowledge is somewhat limited. I can replace the CMP easily. Parts store ordered one in for me for 54 bucks. Really hoping there aint nothin wrong with my timing belt. I was told that transmission control modules dont usually go bad and this is usually some kind of electrical issue.



Just for info here is a list of work/repairs/replacements that have been done to it recently

New catalytic converter
New downstream o2 sensor
Complete Tune up
Cleaned idle air control valve
New thermostat
New fan belt
New rear shocks
New front axle U joints

 

Well, start with the absolute basics first. Check to see that your battery is good and your charging system is as well.
Electrical grounds are notoriously bad on XJ's. Check the one on your battery, the one that runs to the fender wall right from the battery, the two that ground to the block near the oil tube, and finally, the one I have found to be most fickle, the firewall ground.
Check those then check back with results.
If there is any doubt about the ground, check it for resistance or replace it

 

The codes are telling you that there is no signal from the PCM and the Crank Position Sensor. Like the first response mentioned, refresh all your ground points. Don't just wiggle them, you need to remove each fitting, clean it, scuff it back to shiny metal and re attach. It's important because a bad ground could be causing the open circuit condition on the PCM. You should then check your harness connections at those two areas, pop the fittings open, clean and reconnect. Look for any corroded connectors or broken pins.

 

And the CPS wires are in close proximity to exhaust. Check condition and that the section of wire is secured.

 

Thank you all. Will do all this and check back with you.