Have a 1988 jeep cherokee with no spark, checked coil, wires, changed camshaft position sensor and still no spark. Could it be the crankshaft position sensor and if so where is it located? What does it look like?

 

Even though you said you already tesed them it could still be a bad coil or coil wire. Try this test if you haven't already. Get an ignition spark test tool like the one pictured below, the cost lest than $10 from the auto parts store. Check the spark at a standard gap setting then open the gap up to about 1/4" and retest. A strong coil should be able to through a stong spark across a gap of that size, if it can't it probably needs to be replaced.

Also pull the distributor cap and check to see if the rotor turns when the engine cranks. I helped a friend change almost everything electrically related to the ignition system on his truck one time before we discovered the timing chain had broken. We could have paid for a timing set with the money spent on gas to get back and forth the the parts store that day.

 

Try this:
Renix CPS Testing and Adjusting
　
　
Renix TPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the 3.5 range on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.

 

Yes, it could indeed be the crank position sensor.

Its at the top of the trans bell housing, just under the firewall.

It can be a challenge to replace, so most are very sure that its bad before replacing it.