I bought a cam sensor on a 1999 jeep grand 4.0 can I just change the two bolts and change the sensor, Because I put an new sensor on and still no spark. Some one said that # 1cyl has to be on tdc and then it has to be aligned with the right size pin?

 

On the '99 4.0L, you can replace just the cam position sensor by removing the two bolts and removing the sensor from the oil pump drive. Install the new sensor, tighten the bolts and reconnect the electrical connector. You only need to use the pin and place #1 cyl. at TDC when removing the oil pump drive assembly.
Maybe your problem wasn't the cam sensor but the crank position sensor? How did you check/find out before replacing it? Just wondering.
And Welcome to CF!
Dan

 

When the vehicle died it showed 2 trouble codes p340 and p1391 and I went with the easiest thing to change first

 

Well I guess you should/could have checked it first.
The manual tells how to check the Crank Position Sensor before you spend your money. It could also be the wiring, the connector, or the PCM.
Dan

 

After changing the crank position sensor and the car still not starting I started running tests The cps and its circuitry checked out. Next I checked the cam position sensor for voltage and it checked OK. When i checked the output of the cam position sensor it was out of range, so I pulled it and to my dismay I found that pulse ring was not spinning. Next I pulled the oil pump drive unit and it had seized and 3.5 of the helical gears had broken.

My three questions are, is this common/ does it damage the camshaft and where do the broken gears fall to? Oh yeah I still have compression in my cylinders.

 

The right sized pin is a toothpick. I have never done this but a search for syncing cam sensor will give you the process