93 jeep cherokee blowing 30 amp eng. cont. fuse

1993 JEEP CHEROKEE
150,000 MILES • 4.0L • 6 CYL • 4WD • AUTOMATIC
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DUCKKILLER
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Hope some one can help me, My son jump started his buddies truck and as he tells it, he hooked the cables backwards on the Cherokee, he said it was just for a second and instantly the throttle body sounded differently,he drove home and drove to work the next day,on his way home it blew the 30 amp. eng. cont. fuse, I changed it but it will blow it after about five mins. of driving, it can sit and idle no problem, but as soon as i drive it it will blow.
I changed the TPS ,no difference,I get code 12,checked the voltage at the battery at idle it shows 14.33volts,Doesn't change with higher RPM.The battery has been kinda suspicious for a while ,corosion build up from water leaking from the top,when I look in the cells half look black and i found a small piece of rubber floating in one,The volt gauge in the cluster only shows 12 volts or less with lights on. I am leaning towards shorted cells in the battery ,but I would think it would short at idle not just driving,
If any body has dealt with this or can kinda confirm my suspicion ,I would really appreciate it.
Thanks in advance for any help.
Jun 6, 2014 at 9:36 AM
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WRENCHTECH
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Shorted cells in the battery won't blow a fuse. He likely melted some wires together somewhere.
Jun 6, 2014 at 9:53 AM
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DUCKKILLER
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I can't find any burnt wires anywhere,And I would think it would blow it just idling,ran around jerking on all the looms and banging on fuses and relays and sensors and nothing, it will only blow when I drive it around the block,Within 2-5 mins.
Jun 6, 2014 at 1:21 PM
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WRENCHTECH
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You have a dead short in the circuit somewhere and they can be very difficult to find.
Jun 6, 2014 at 2:25 PM
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DUCKKILLER
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Well here is the new situation.I disconnected the battery to load test the battery, which obviously reset the computer, The load test showed all ok with the battery.I hooked up my meter and took it for a drive to see if the alternator was surging or anything ,It now shows 13.4 volts at idle and goes as high as 13.8 at high speed, And now it wont blow the fuse. What the hell ???I,m guessing when it reset the computer What ever was doing it went back to normal, For now?
Jun 7, 2014 at 2:50 PM