Hey all, my kid parked his Jeep up on Friday evening, been having no problems, come to start it Sunday morning no start, no spark, changed the CPS and started right up, just curious as to whats inside this thing that would let the Jeep start one day and not the next.

Anyhow running great now..

 

It's a Hall Effect Sensor.

 

They do tend to crap out with no warning.

 

is the crank sensor a common issue on the 4.0 because my brother has one and he was driving to work and and it died on him, but restarted and was running rough and if u gave it any throttle it would die, and now it wont start

 

His problem sounds more like a fuel pump.

 

CPS (CKS, actually) is common. Sounds like a FP or possibly the pickup coil (inside dist, 30$ at pep boys). You need to check the usually spark, fuel, air and see what's missing.

 

ya thats what i told him, im at work and cant physically check those myself, im gonna guess a fuel pump but ya never know