1999 JGC 4.0 -- Run great, next morning turns over, but won't crank. Key light w/ line through it stays on, Fuel guage shows empty, no fuel pressure at Fuel rail pressure releif valve.

Unplugged CKP & turn key on, but key light did not go off. Jeep is at Dealer now. TECH said: Scan tool is not communicating w/ PCM (New one I bought and a Test PCM from Jeep). Scan tool read other components, just not the PCM.

Can this still be the CKP or does someone have been through this before and may know what problem is.

Only car we have. Just need advise. Thanks!!!

 

Sounds like you ned to find a new dealer/parts source.

Scanners will not communicate with a PCM if there isn't any power available to the PCM, even with the Key Off. Could be as simple as a blown fuse or bad wire/contact.

All Jeep PCM's complete the ground path for the Auto Shutdown Relay (ASD) and Fuel Pump Relay (FPR). If the PCM isn't receiving power it can't do this.

Step #1
Confirm proper power to the PCM.

Unplugging the CPK has nothing to do with the lack of fuel pressure or a no crank condition, and it certainly won't shut off a CEL.