The crank position sensor is at the rear of the engine below the crankshaft. You need to remove the transmission and flex plate to get at it.

I think as long as either the cam or camshaft position sensor is working, the engine may run, perhaps poorly.

 

Before ripping the tranmission out, you may want to check the integrity of the harness. Look for corrosion in the pins. May sure the PCM is providing 5VDC to the sensor and you are seeing a +5-0V square wave signal when cranking. If you are getting 5V and seeing a square wave, the PCM may be bad. If there is no 5V, then the PCM is bad. The service manual has more detail, but it is in a several page and lengthy process. IAW difficult to copy and paste here

 

Thanks for your help. Too big a job for me so have sent it off to Jeep.
Spoke to the mechanic who said there's a chance it could be down to a recall involving a software update. Doubt I'll be that lucky, but fingers crossed.

 

Was wondering if it was recall or sensor as I’m having same issues with mine