X2.
you might have a bad solenoid. get under it with a screwdriver. lay head to the motor, feet to rear. face the starter. arc the connector with red cable to the one below it. at this point you're bypassing every security feature and running juice into an electrical motor.

 

i got a 99 cherokee for $900 and it did that ended up being the crankshaft posision sensor then she started right up

 

My XJ is a Limited with factory alarm.
Okay here's what I got. Sometimes I would accidentally trigger the alarm. This has been going on for years. Key in driver door does nothing. Key in passenger door never triggers the alarm, but quiets it when it happens.

Intermittent no start, been going on for over a year. Throw it in "N", sometimes it fired right up. Sometimes it would just fail to start and go nuts. Open a door, the horn beeps; turn on a light - the horn beeps; any type of electrical action, the freaking horn beeps! I would disconnect the battery for a few minutes and it would go back to normal. Until the next time. 3 weeks ago I had the NSS cleaned. Days later it absolutely refused to start right after I drove it 3 blocks & parked for no more than 10 minutes. I let it sit for a day, banged the starter, it fired up. Drove it 3 blocks, parked in my friend's driveway. It sat until yesterday: now absolutely nothing from the starter. My battery's fine & everything else works. Today after AAA & new starter, she fired right up. Hey, it's 18 years old. It was long overdue. I can't complain.

We have the exact same symptoms. the same gremlins. I dunno if I want to disable the factory alarm. I like an alarm that blows the horn & I hate aftermarket sirens. Might try to find where the gremlins are. We'll see.

 

if ur positive terminal is hot that means u have a short somewhere.

 

Well, problem resolved. The positive battery terminal had so much dirt in it that I suppose it just gave up. I put a new terminal on yesterday and off I went.

Thanks for all the advice guys!

 

No prob Dude.......If you still got the stock terminals you oughta think about replacing them. They make these brass marine ones that the wires connect with a wingnut and a post. They are real primo looking. Whenever the ones I got wear out I'm thinking about doin that.

 

I have 97 Jeep Cherokee that had similiar issue, Turns out it was a 15 dollar relay in the pdu Starter relay ( on 97 it is unit 2) in the pdu. It took me less than 5 minutes to swap including opening, closing hood, and replace relay. and starting successfully the Jeep

I got mine at O Reilly, and it was less than 15 dollars with tax ( in Arkansas)
Hope that helps. Everyone else I spoke with around here keep telling me the computer failed or the NSS had to be replaced.

 

that happened to my gc and i pulled my hair out for a day and finally cleaned my terminal and made sure they were tight and then it started right up

 

I'll have to try this! I think my ECM and SKIM aren't communicating thus causing my 99 XJ tostart then stall. The "no bus" code and theft light come on the dash as well. I've replaced the ECM twice becuae of this issue ONLY after haveing a machanic tell me that the only way to reset the factory "No run" feature in the alarm was to relpace the ECM! Let's just say I haven't gone back to that idiot! Hopefuly this will be a fix! Thanks!