Starter Diagnosis Woes - HELP??

Okay- just yesterday when I stopped off to get an ice cream in the mild swelter of los angeles - I came back to my vehicle to confront a nasty no-start condition. I got what is presumably a solenoid click but nothing else and then shortly thereafter nothing at all - not even a reading on the battery gauge or instrument lights.

I get a jump and it starts up FINE - so I'm thinking there's something wrong with the batter or charging circuit. I head over to Pep Boys (a local auto chain) - they test my battery and get 770 CCA on it and a clean bill of health. Now I'm scratching my head a little - thinking it must be a bad ground or a 'devil in the wiring'.

I come back home and peruse for some hints as to how to diagnose the starter and let that percolate a bit.

I just finished testing some of the connections and get:

battery negative to body (ground) = no resistance
battery negative to engine block (ground) = no resistance
battery positive to distribution center pos = no resistance
battery positive to starter positive = no resistance
battery negative to starter negative = no resistance

so please forgive me if I'm missing something kind of obvious here - if the battery is good and fully charged - should the starter not be turning over here??? What am I overlooking that would permit this kind of condition - that would allow the starter to work perfectly only when I'm getting an external jump despite a perfectly good battery?

::cough:: what year?

duh...! sorry - I meant to post it all below.

1992 Sport
1999 4.0 HO
mitsubishi starter
1/0 welding cables on everything major

thats about everything relevant I can think of...

A click and no-start is most commonly poor connections. No battery gauge or instrument lights tends to confirm this.

Begin with basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds. On older Cherokees consider adding an extra engine block to body ground cable.

Test the starter. Test the battery. Test the alternator.

Have your helper attempt to start while you give the starter a few gentle love taps with a hammer.

yeah - I tried the hammer trick but it made zero difference in the result. The other thing I should have mentioned - the last jump I got - things were REALLY labored in turning over - making me think it HAS to be a bad connection SOMEWHERE.... problem is with the 1/0 cable and the beefy connections I have on there - it's REALLY REALLY time consuming and a PITA to pull things apart for a good scrubbing - trying to figure out how to narrow things down to a specific area...

The thing that's BLOWING MY MIND right now though - the day before I was in the desert near mexico in 114 degree heat - 100 miles from ANYONE or cellular service. I mean - thank GOD it didn't happen there!!! I'd be TOAST. Literally.

Awesome.... thanks for the hand holding - sometimes that's all that's needed... nothing made sense to me at all until I thought go check continuity between the main positive LUG and the leads - for some reason I thought the culprit would have to be between the battery post and the lug/clamp - but it ended up being between that and the cables... gave em all a good scrub and soak in sulfuric acid to get rid of all the oxidation product and it fired right up!

Thanks again.

QUICK QUESTION: To di-electric grease or NOT to di-electric grease... I put a small amount on - but it also occurred to me that the grease would also electrolyse over time and become potentially insulative. I know it works great in the short term - but wasnt' sure about the long term...

Dielectric grease IS an insulator to start with and remains so. Its value lies in excluding oxygen and moisture from connections, especially in multi-circuit connectors where a conductive paste would cause a short.

To promote conduction and protect against oxidation use a product such as Ox-Gard available in the electrical wiring departments of home stores.