OK, I'm at my wit's end with this damn '96 Jeep Grand Cherokee that I sold my brother. We finally traced the problem to a bad CKS and replaced it. Got the truck running and it idles fine, but now it has an intermittent misfire at RPM that is getting worse. Yesterday, it threw a code. Put the reader on and it says the code is "intermittent signal from CKS or CPS." Since we had a known good CPS laying around we swapped it out. Still runs like crap. Put in a new cap and rotor just for grins and giggles. No improvement.

My understanding of the CPS and CKS is they either work or don't, no in between. Is it possible we got a defective CKS that would allow the engine to start, but be misreading the reluctor ring and causing a misfire or intermittent signal that results in poor performance? This vehicle was running perfect before this all started and it got a new cat and 02 sensors 2 years ago. It isn't throwing any codes other than the one previously mentioned. HELP!

 

I love jeeps....SO lets try to work this.
First is this the lengendary 4.0- I6 or the v8.

What is the code # you keep getting? always post ALL codes
Any recient work or modifications vehicle is STOCK?
Will your scan tool read what is often called Manufactures specific?
If not sure get a free code ck at autozone.

 

4.0 I6

1439 I believe the code was. "Intermittent signal from CKS"
Vehicle is Stock
Yes

 

Can you confirm p1439?
the CKP codes are p03xx..??

 

unlikely that 2 different cks's would be bad. i'd guess bad wiring or connect, either at pcm or cks. has the engine every been out. if so, its easy to pinch the wire. follow the wire. any place where it may be grounding out. connectors - clean and put a little di-elec grease on them.

don't you hate it when you sell a vehicle to get rid of it and end up working on it anyway.

 

Got a CKS from the dealer today. Will try it over the weekend. The vehicle is entirely stock and never had a single problem in 10 years that I've owned it (beyond brakes, batteries and tires). It was running great until 3 weeks ago when it just refused to start one morning.

Yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes, yes.

 

OK, well it looks like we got the problem solved. The no start issue was definitely the crank sensor. The poor running after replacement of the sensor appears to have been caused by a poor quality replacement part. We got a factory crank sensor from Jeep on Friday, installed it today and the truck is running just like it always has, perfect. The replacement is going back to Autozone tomorrow for a refund. I never thought a brand new Duralast part would cause an issue like this, but live and learn, I guess. Thanks for all the help and suggestions. We really appreciate it.