what can cause the mega fuse to blow when i hook up the battery cables... installed a new highway 15 wire kit as per directions for gm.. hooked ground cable to negitave and when hooking cable to positive i got an arc like it was shorting out and blew the mega fuse...
I may have the answer for you. We used the same American Autowire kit in my Son's rpu and after we got it running the mega fuse would blow after driving or running the car for just a little while. I called AA and the tech there was basically an ass. His attitude was as if we were stupid for putting the fuse in the location we had, he said it wasn't made to handle that sort of load, it was made to just protect the wire that goes to the ignition switch. We had it installed in the starter circuit because that is the way the instructions kinda showed it. Their instructions were really good, EXCEPT for the part about the mega fuse. Take another look at your directions and you will see where it is supposed to go. It has been about 4 years since we had that discussion with them, so I am a little foggy on the exact details, but basically, the mega fuse does not go into the battery cables, too much amperage is going through there for it to handle it. Don
Maybe, and I wish my memory were clearer on what we had going on back then, but sometimes our fuse would blow immediately and sometimes you could drive the car a few miles, then it would suddenly quit running. But I bet the mega fuse is just hooked up wrong somehow. Don
Leave the ground connected to the battery. Leave the positive unhooked and check it with a voltmeter to ground. I bet it is got a straight short to ground. Start un-plugging circuits until it doesn't short to ground. Then take a look at the last circuit you un-plugged. I would probably start with the "starter circuit".
Adding to this, you got a short before you get to the fuseblock. Maybe your fuse block is contacting the firewall, or whatever, in a bad way.
i have one 8 gauge wire from the starter and one 8 gauge wire from the altenator going to one side of the mega fuse and one 10 gauge wire going from the other side of the mega fuse to the ignition switch..
I still say you are grounded somewhere. Maybe a pinched wire? A terminal grounded to the ign switch case?
If you have it wired exactly like that, unhook the wire that goes to your ignition with from the switch. Run a smaller fuse in place of the maxi (cheaper to pop cheap fuses) then hook up the cables. If it pops the fuse that ign switch wire is pinched/grounded, if it doesnt then un hook the wires from the ign switch and hook the main ign wire back up. That will let you know if its a bad switch.
Mega fuses are ideal for battery and alternator protection and other applications that use heavy gauge wire and require ultra-high current protection. The Mega fuse helps in allowing electrical components to draw the current needed and protect the electrical components from overloading. Mega fuses are available in high amperages of 100-250. And it takes a LOT of juice to pop one,,,,,,, like a direct ground.
wow, ok, and what "traditional" hot rod/custom needs that much juice? and back to the original question: where is the positive side of the battery hooked to? down at the starter? or on the same side of the mega fuse as the ignition switch, or the other/alt./starter side?
If the main lead is blowing that fuse, then the main lead is shorted somewhere along it's length or at the fuse block. If you pulled all the fuses on the fuse block, and the main lead still reads grounded with an ohm meter, then start following the wire in it's entirety. I would also dismount the fuse block, and check the backside to see if anything got pinched or touching when mounted. Might be a factory defect in the fuse block also.
If you have a megafuse in your main +12 circuit that drives the starter (like I do) it's somewhere between 150 and 200 amps, right? If that's blowing then you've got a dead short somewhere in one of the bigger wires in the circuit, maybe right at the starter solenoid, 'cause if it were anything small you'd have burned up the wire by now.
Just because it's not traditional doesn't mean it's not a good idea. There have been a lot of improvements to wiring system design over the last 80 years.
Come on, you're running a zips riser and aluminum radiator. We all build safety and reliability into our cars that maybe arent pure gospel.
Blown mega fuse is a dead short or crossed wires. Could have the cables crossed, internal short on the alternator or starter but if its blowing that as soon as you touch the cables it's a big short.
worked on it today.. disconnected all the wires on the ignition switch.. clipped all wire ties that bundled all the wires together (which included the coil wire, distrubitor wire to ballast resistor, sender wires, gauge wire to fuse block) .. put a 30amp inline fuse between the mega fuse posts... connected the battery, fuse did not blow.. connected the wires to ignition switch one by one, fuse did not blow.. cranked engine over, fuse did not blow... the only thing i did not reconnect was the gauge cluster disconnect terminal
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