sh0kk86

was driving, charge and brake lights come on

get home, pull alternator, go down and test it at vatozone, tests bad, so i buy a new one. put new one in. drive around a bit, radio starts turning off/on, lose all gauges, lights, all power to the truck except headlights which were running off the battery.

took the new alt back, still tested good, so i replaced the section of wire that goes from the 80 amp fuse to the positive terminal of the battery, since the old one looked bad.

this time i get to drive around the block but it still blows the fuse before i get back to my house.

anyone have any ideas?

scope103

Which fuse? If you are blowing the 80amp fuse, I would guess that the "new" wire could be shorting to ground somewhere. OR, it is shorting after the 80amp fuse on the way to the alternator. 80amps will make a mess, so it shouldn't be too hard to find a contact point.

If you don't see anything, you could try disconnecting the B wire (the one to the big stud on the alternator) and starting the truck. Then check the voltage on that stud; look for about 14.1v. [What I don't know is if the regulator will settle with no load at all; you might need to put a 1 amp load (like a taillight bulb) on the stud to get it to the regulated voltage.]

How are the other three wires to the alternator? If you lose the S wire the alternator won't produce power.

Good luck!

sh0kk86

hmm, s wire? is that one in the round connector?

i have the round connector plugged in all the way to the alt. the b wire is on tight, and the ground wire is grounded by the powersteering bracket.

abecedarian

alt should have a large gauge white wire to a stud on the alternator and a 3 wire plug with white, red and yellow wires coming from it, and a ground lead.

All are fine?

sh0kk86

doesnt matter if the top one is tight, if the bottom one isnt. :\
this could be why it was shorting out.


on a plus side, i now know my electrical is in good shape after rewiring all the grounds, alt wiring.
thanks for the help

abecedarian

Given one was loose, it's likely nothing was shorting. Rather a loose connection will increase resistance and in turn increase amperage and blow fuses.

AZkid

mine kept doing the same thing, it blows the fuse that recharges the battery, i thought maybe it was the alternator, had it tested, bad when tested, got a new one, same thing, bad when tested, got ANOTHER new one, same thing, bad when tested, kept shorting the relays in the alternator, finally i bought a more expensive alternator and hasnt done it since, dont know if this helps, or even makes sense, but thats my story.

ken o

I just had the same problem and I think I have it fixed. The "ENGINE" fuse feeds the voltage regulator, but also handles about 6 other things also, including directional signals, backup lights, and several relays. Pull the fuse and plug in a test light. Turn on the ignition, and the light should go on bright. Start moving wiring harnesses around and disconnect connectors until the light blinks, dims, or goes out. That would show your short location. Mine was a bad backup light switch or something in the backup light circuit. I have no backup lights at the moment, but everything else works again.