Yet ANOTHER no-start

[D-goXJ]

Have a stock 89 Pioneer 4.0 I6 with auto trans. I am new at this. I am a girl. I know next to nothing about 4x4s. Forgive me if I sound stupid here-- just want to get my Jeep fixed.
I just bought this from a dude across town. When I test drove it, twice, and then the day I went to pick it up, it started and ran fine. However, after parking it at my place for 18 hours (it did snow that night), I went out to start it up and nothing. First it cranked but wouldn't start. Jumping did nothing. Then, I tried to start it in neutral and when I turned the ignition, it just gave me a click and nothing. I can hear a ticking noise coming from the dash when I turn the key.
The starter, alternator, spark plugs and battery and cables are all new and have been checked-- they all work fine.
It sat for about four days and I had a friend come to look at it. Wouldn't you know it, it started right up, on the first try, like there was nothing wrong. He checked my battery, saw nothing wrong. It started fine after he cheked the battery again.
Later that evening, I went to start it up, but it went back to clicking. It hadn't snowed. No cranking, just a click and nada. The next day, same thing.
I am resigned to having it hauled to a mechanic, but I would like to at least suggest to them that they look for... something. Any ideas what this is? I have read a few threads about CPS units and whatnot, but when I told the mechanic it sounded like a CPS problem, he said "What's a CPS?"
MAKING ME NERVOUS.
Help. Any thoughts?
KT

[XJJD]

Yea, I would stay away from that mechanic. I had a CPS go out on my xj it's really easy to fix. and will cause an intermitten start issue like that. JD

[MoparManiac]

I know that sometimes, randomly, my jeep doesnt like to start because of the NSS (Neutral Safety Switch). Try searching for that and see if it turns up your symptoms. Does your jeep actually try to turn over but doesn't catch? Or does it not even crank? If you switch between N and P a few times when this happens while attempting to start it in each position you should get it to start if its the NSS.

[xjbubba]

Sounds like multiple problems that could have a central failure. Since one symptom is clicking and no turn-over, I'd start there first. A CPS problem would not cause that symptom. You have to know what components could cause the symptom your chasing, then devise tests to isolate and rule out each component. For instance, clicking when you turn the ignition key to start indicates a problem in the start circuit. The components are the ignition switch, trans neutral safety sw (auto trans only), the start relay, starter solenoid, battery, and all associated wiring, including grounds. The clicking indicates the start relay is not engaging either because there is not sufficient voltage in the battery (test battery with a meter, should read 12.5v or better), or the ignition switch contacts are burnt or corroded, or the battery cables (both hot and ground) are loose or corroded, and not allowing sufficient current to flow to engage the starter relay. The start relay itself could be bad, or the wire connections to it are loose or corroded. Trace the associated wiring and disconnect and clean each connection.

[D-goXJ]

I ran some tests and determined that it is likely the Neutral Saftey Start. I am able to start the car if I have it in neutral and apply a litte pressure on the shifter while turning the ignition. I can feel it catch and then it turns over and starts. Found the part I need on eBay and can replace it myself. Saved me from having to go to a mechanic who sounded sketchy.
Thanks for the help, guys.
KT