First Jeep and I'm 76 yrs old. It's a 1998 Cherokee Sport. Pretty sure it's the pcm or cpu whatever. Where the heck is it? Not on firewall. Help me locate it please.

 

The PCM is located on the driver's side, near the front of the engine compartment. Between the air filter box and fender. Behind the driver side headlight.

 

When did this start happening? Does it crank?

 

found it right there. Good response.

 

Bought it like that. hahaha

 

Rick, don't be so sure on that PCM Rick. Always exclude everything else first. Computer replacement is a "diagnosis of exclusion"

You need to determine if you are missing SPARK of FUEL. Remove a spark plug, place the plug electrode next to a good ground with an insulated pliers. Have a buddy crank the engine over while you look for spark. You are looking for a strong, BLUE, snapping spark. Yellow/orange/white indicates a weak spark which is often caused by a failing ignition coil.

If spark is good (and only if) then introduce a small amount of gasoline into the intake. If the engine starts and runs for a few seconds, you have identified a fuel delivery problem and further diagnosis would be required.

The above troubleshooting is if the engine "turns over (cranks)" but does not actually start. If the engine doesn't even turn over, advise and we'll give you some tips for that. The term "no start" can mean more than one thing...

 

Please heed TJ's advice. He's an old bugger, too, and he's been around the block. Replacing your PCM now would be a mistake. There are many other things that could cause a no-start.

 

I agree, the engine computer (PCM, ECM, etc) is the least likely culprit. The number one on the most common cause for a crank and no start issue is the crankshaft position sensor. TCM is the transmission control module, btw.