Renix Electrical Issues

I have a 90 4.0 xj. Other day it randomly shut off while driving (radio wasnt on), Yesterday it was cutting out when my sub was turned way up, every thump it'd cut out. This morning I started it and when I put it in reverse it died. I started it and when I hit the brake it would cutout. Signs of a bad battery too me. (Very likley,I have a 1200w Kicker L7 hooked up with no cap).
So I put a fully charged spare battery in. No start. Check and I have no spark. Wiggle the ICM and it creates very weak and random spark. Remove the ICM and the middle terminal of the 3 prong connector is melted. I believe thats the ground wire, but I am not sure. I do have 4ga wire from alt to batt and 6ga from batt to starter relay. Unfornently I was lazy and Never installed a fuse inline.
So now for my question. what terminals are what on the ICM,and what could cause that terminal to melt? Short to ground? Also, the shutdown while placingin reverse, has anyone experienced this when it wasnt a bad battery? I DO NOT HAVE AN ALARM.


-----NorCalChris

Btw, CPS tested good.

Thx 8mud. I checked resistance/continuity between (B) and B- and ohmed out good. Between (A) and B+ ohmed out good and I measured 46ohms between (A) and B-.

To the best of my knowledge there is no way to successfully test the ignition module, some of the chain auto parts stores have a tester.
The coil separates from the module and can be ohm tested. If I remember correctly the coil grounds through the outside metal to chassis and the ground wire on the module is redundant.
I'd separate the coil from the module and test for short. Dismount the module and clean the mounting screws. Maybe run an extra ground from the top coil mounting screw to chassis. Another ground may do nothing, but might be a little insurance just in case.
I think it likely your coil is shorted (high voltage) or maybe a short in the module. A high voltage short in the coil can burn stuff up fast, I've seen them burn right through the side of the coil housing.

Thats the only thing I can think of right now. Yesterday when I was testing stuff, Everything tested good. I didnt test the coil yet, but figured the coil must have shorted out internally and blew the connector. Im going to go to the junkyard sometime to get a ICM and coil. Hopefully thats the problem and The "new" assembly doesnt burnout too.

All is,good. Repaired the harness, replaced coil & ICM. Started right up.

Congrats.