Possible Electrical Short?

See attached pdf. for other fuses. Are the fuses all good? Or does it still blow the gauge fuse.

 

So I'm the friend whose been assisting in the fun. Grounds were checked with an ohm meter from the negative post to various points under the hood, on the engine, and under the dash. Couldn't get anything but zero ohms anywhere including moving various wires. When we put everything back together and started it cause I wanted to see it die, immediately after it died, battery dropped to 9v and came back up to 11 within seconds, I immediately unbolted the positive cable and hooked up a test light inline, and only a faint glow from the radio memory. So faint only visible in the shade if you cupped your hand around the light. Supposedly the shop that "tested" the battery charged it, and after 20 minutes of the engine dying was still only at 11.9v which is completely dead. But no current draw inline which makes me think it's not a short just a bad battery. It was six years old and we live in a desert. New battery was 12.65 until engine started 12.4v had 12.4 at the alternator, but Napa tested the alternator . So I'm curious as to the three wire connector at the alt. One wire goes to the gauge, one is for sensing voltage, and the other is for? I'm familiar with older Toyota's and various makes and models but don't have a good wiring diagram in front of me. Could the alternator be not getting any voltage for the three wire to energize it? That would explain it not working in the truck but functioning when on the test bench at napa? Can anyone explain what the three wires go to, and what voltage should be there with key on engine off and key on engine on?

 

Key on engine off 2 of the smaller wires should have power, red and white and of course the big wire will have power. The yellow wire controls the dash light and signals the DRL's the engine is running by sending power to it. The smaller red wire is the signal wire for the alternator regulator to turn on. Small white wire is the voltage sensing wire.

 

If you got 6 years in the desert out of a battery you're doing better then most

 

I posted a wiring diagram in the attached pdf above.

 

OK so looking at that, the red wire is tied into a 10a fuse. Is that the gauge fuse?

 

yes

 

Have you ever determined what causes the gauge fuse to blow?

 

Which would be the fuse that keeps blowing.. I'm 20 minutes away from the taco right now. Need to finish moving into my new place today and clean my condo, but hopefully monkey will check those wires and report back his findings.

 

I'm hoping that tbe dead battery was the cause of the dash fuse to blow. Haven't run the motor much at all to determine if that problem really is fixed or not. All other fuses look good. As far as the alt wires, white is reading 12.47, red is at 12.34, and yellow is actually at 12.15.

 

And I dont know what just happened, but all of a sudden I'm getting 14.3 v at the alt. I'll keep this running for a bit to see if its okay now..

 

Its been running for 10 min now with a.c., radio, lights all on to create as much draw as possible. Reading around 14 v still with everything? I'm not really a fan of things fixing themselves when I haven't done anything...could it have been a bad connection somewhere that I just fixed when doing all these tests? I will keep an eye on everything but it always worries me when the problem just disappears.

 

Try wiggling the wire harness for alternator while its running. See if the voltage fluctuates at while doing that.