okay so i noticed that my battery cables were coroded the other day, so i figure that i would save myself some trouble later on and get some new cables. went to my local parts store and they tell me that they cannot tell me the length needed and i cannot fond anything online anywhere so can someone help me out?
Unfortunately the OE battery cables for your 96 4.0 are part of a wiring harness to alternator, starter, etc.. Did a search for it (#9 in diagram, 5601778) and $100, discontinued online, so maybe only the dealer would have it at even a higher price. It may be time to make up some new ones.
BTW, be sure and check the PDC connection from the positive cable to make sure it's not corroded too. And can't stress how important it is to clean your 3 ground connections on the block. There's 1 on the oil dip stick tube bracket bolt and 2 on the coil studs by the passenger side motor mount. A bad ground (oil, rust, corrosion) on one of the coil studs took out 2 of my PCM's along with a couple crank sensors. This is the only ground for the PCM which in-turn grounds all the sensors and it's a vicious circle. Good luck.
Just thinking ahead to an issue that may become relevant to me, how feasible is it to make up your own battery wiring harnesses? Is it a major PITA? I've just checked the availability of the 1993 4.0L battery wiring, and up to 7-16-92 is now discontinued, but 7-17-92 onwards is still coming up as available - at an eye-watering $217 (and that's after online discount). My ZJ is an "early build" 1992 model, so I guess that means that the OEM harness is no longer available.
Wow AVR2 that is a high priced battery harness! I too would like to make up my own cables but don't need all the wiring that comes with them. Wish I could find the thread but about the best battery cable set-up I've seen is where a guy used the military style battery terminals like below. Then he increased the cable gauge while buying all his parts (HD coated lugs/eyelets you solder on with solder pellets in connector bottom using a torch, etc.) at a marine supply store. Then he used thick shrink wrap to cover the solder joints and connector ends. Know some use welder cable but that stuff's pricey too.