Hey guys, my 99 4.0L has died at right after startup a couple times recently. Just got in it and drove a couple blocks and it died and wouldn't start for a while. It keeps dying now but I got it home. I'm gonna get started researching, but any help would be awesome!

It threw Code P0320.

PS: 3000 miles on Rebuilt Engine.

 

It may sound silly, but take off both battery cables, and clean the post and terminals thoroughly. EVEN IF THEY LOOK CLEAN.

A skin of corrosion will make this car do insane things, and a simple cleaning with steel wool may save you a ton of headache.

And it's free.

 

Ranger is right! Low voltage supply can make the PCM do weird things and shut it down or give erroneous gauge reading, all sorts of strange things! Also check the cables where they go into the battery terminals for corrosion. There are 2 wires that supply power, one is just for cranking the starter and the other is for everything else on the jeep and goes to the PDC (relay/fusebox under the hood).

The P0320 code relates to the loss of signal from either the cam sensor or the crank sensor, but it can be cause by low system voltage. I had the same problem with my 2000 4.0 WJ and had no code. After checking for bad connections which didn't help, I changed the crank sensor with a Mopar part and it fired right up and ran perfectly to this day! Not surprising because the original had 175K miles on it! I can't stress this enough, use an OEM Mopar part. They are made with neodymium magnets where aftermarket ones aren't.

Mine didn't stagger or stutter, it just shut off like I turned off the key. This was caused by the PCM making the decision to drop out the ASD relay.

 

My '99 was doing the same thing & throwing that same code. I changed out the Cam Sensor & Crank Sensor with genuine Mopar parts. I've seen a lot of Aftermarket sensors go bad after like 100 miles on these things. Been running like a champ ever since.

 

Thanks guys, I have a brand new battery and clean connections. I put a new Crank Position Sensor in it. It's good now. I watched about 20 youtube videos. I was about 70% Crank and 30% Cam. Luckily I was right. I even let it get up to around 220 for a while just to make sure this one was good. They tend to run okay till they're hot, or just a little hotter than you'd like.

PS: Dave are you in the CherokeeForum Facebook Group? It's like here, but you get way more attention and quicker answers. You were such good company during my engine rebuild. I actually posted on there about 4 days ago "Does anyone know if Dave1123 is on here? He was a lot of help during my rebuild, it would be cool to put a face to the name.".

Remember her?


She's got about 3K now. And that Crank Sensor is the first issue I've had.

 

No man, I'm a dinosaur and don't do social media! Besides that, I work nights and don't have the time. I'm usually sleeping in the afternoons and this forum is about all I can handle, although it's getting boring answering the same bloody questions all the time, like "crank, no start" and "overheat". It seems too many people don't do any diagnosis themselves and instantly ask us what's wrong. I enjoy staring at a thread and thinking about the least obvious answers to a problem, going thru the system in my head. I hate it when people use the "parts cannon!"

What makes it more difficult is the forum gurus have decided to remove the vehicle information from the profile box and it's tiresome to keep asking "what vehicle" and "what engine" all the time.

I thoroughly enjoyed your rebuild and it taxed my brain a lot to think of all the necessary steps that needed to be done. I got the warm fuzzy feeling when it worked out. Glad I could help!

You can always PM me for a response, you know!