99 XJ 4.0 no start has me baffled
 

It was running just fine until 2 days ago. Went somewhere, parked it and when I got ready to leave...........nothing, not even a click. The only thing of significance that I can tell you is when I turn the key to start, all lights and chimes go off and stay off for several minutes, even after I've removed the key but, the battery is still showing good voltage.
Battery voltage shows 12.71 volts. Battery and cable ends are new. I've checked for resistance (using a multi-meter) between the battery post and cable end, between the battery + and the starter solenoid +, also between the battery - and the starter solenoid - and found none on either. I've also tested all ground points for resistance and found none. Tried swapping the starter relay with one of the others.........nothing.
All of the fuses are also good. I even tried bypassing the ignition switch by shorting the 2 starter solenoid terminals and it had the same effect as turning the key to start.
I did get a .002 ohm resistance between the battery - and the grounding point on the fender but, I've cleaned that and it now shows 0.

Have I forgotten anything or do I just need to take the starter in to get it tested?

So right now it doesn't start at all? Or does it start sometimes? How did you get home man that sucks

Are you getting voltage to the starter?

when you jump the starter sol and it cranks,it should start with ign on in park, be careful!!
i had to do that when i had starter trouble, got NEW starter, a reman failed ..
if it dont crank,the starter is bad.

Sounds like you have a bad connection to the battery. Either loose or corrosion or something. Wiggle the battery cables around until you hear power back on. I e had this happen lots of times. Sometimes it'll take several tries even.

Doesn't start at all, doesn't even click.
I had it towed home.

Yes.

Tried that first. Cable ends are tight, won't move at all and as I stated in the original post, I've tested all the cables. Everything has solid connections and the cables aren't corroded.

You try starting it in neutral? If everything else looks ok, it could be your neutral safety switch.

Jumping the starter solenoid terminals (which completely bypasses the ignition switch and NSS), produced the exact same result as turning the key to start so, it's not that.

just what is that?
if no crank,and, you jump the starter, the starter is bad.
think weve been there.

DOES IT EVER CRANK UNDER ANY CONDITION, LIKE THE STARTER ROTATES
???

If putting power directly to the starter won't spin it, then it is bad.

Fixed!
 

I'm still unsure as to what caused the problem in the first place but, It's working now. I'm not sure I actually fixed anything but, it did at least make the problem go away.

I was out there, about to begin removing the starter when I had an apiphany.
If turning the key to start, causes ALL of the power to go out and not come back on for several minutes, there's just no way it could be the starter. On a whim, I loosened and disconnected both battery cable ends from the battery. Waited about 2 minutes, then reconnected both and tightened them back down. Went back to the drivers door, light came on when I opened it and the chime started when I inserted the key.........all good so far. Gave it a try and it fired right up. Let it run for a few minutes, shut it off and tried again..........starts every time now.

What you described is a classic symptom of a bad battery connection. The reason it wasn't obvious, even though you used a multi-meter (good job for doing that), was because you did not test under load. You will not see the true voltage drop in a circuit until you actually try to use the circuit. So the resistance between the terminal and the clamp could be zero, but the voltage drop once you turn the key could be 5 volts (just a random number), but that voltage drop will cause various symptoms such as the starter solenoid failing to switch (a click, a bunch of clicks, or nothing at all), but it can also cause the computer (PCM) to protect itself from the low voltage and basically shutdown for a time. This will cause the "total power failure" you observed.

I was pretty confused the first time I ran into it as well. I was actually tightening the battery clamp between tests, and was convinced that couldn't be it. However, I had sprayed some anti-corrosion product on the terminal a few days prior, and it was getting in between the post and clamp. Turns out the product is non-conductive, and if your posts/clamps aren't completely tight when first applied, it will simply creep right between them and cause problems (as I learned).