Alternator wiring

[AZFX4]

So Im buttoning up my 4.0 swap and I seem to be having an issue with the alternator wire. my 4.0 comes from a 91 explorer. There is a heavy wire that runs from the lug on the back of the alternator to the starter solenoid, at least thats what I thought but when I hook it there and then hook up the battery my voltage drops and the solenoid gets to smokin...any thoughts here? Everything I can find says that this is where it should be hooked up so im not sure whats up.

 

[Earl43P]

http://www.therangerstation.com/tech_library/chargingsystem.htm

http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_charging_1991_1.JPG

Make sure you put it on the de-energized side of the solenoid. It's bussed there, not switched.

 

[AZFX4]

http://www.therangerstation.com/tech_library/chargingsystem.htm

http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_charging_1991_1.JPG

Make sure you put it on the de-energized side of the solenoid. It's bussed there, not switched.

When you say the de-energized side what do you mean? looking at that diagram it shows it hooked to the same post on the solenoid as the battery. The way I have tried it and the way I keep seeing it in these diagrams is with the battery, distribution box, and alternator wires all on one side and the single starter wire on the other.

 

[Earl43P]

Exactly.

 

[AZFX4]

Well when I hook it up that way it starts cooking the battery so something ain't right there.

 

[flatblack]

alternator hook up

( + ) Battery hook up

Diode block

 

[AZFX4]

Well I have it hooked up exactly as you show it in your pics, but isnt the battery cable the one on the left? The one that splits off to the right side lug is a small wire that goes to the starter...

 

[flatblack]

Check the diode block. On your muti meter most have a diode test circuit.

You will get a reading one way and not the other if you get reading both ways there is the problem.

 

[holyford86]

That big wire on the back of the alternator is what charges your battery, it can be hooked directly to the battery positive terminal (like mine is) and be fine, if you're hooking that up and it's shorting out and smoking then you have a wire hooked up wrong or the alternator is junk. It should be hooked to the always hot side of the fender mounted relay, the small wire leading off of the switched side only pulls in the starter mounted solenoid to start the truck, nothing else should be hooked there.

 

[AZFX4]

It should be hooked to the always hot side of the fender mounted relay, the small wire leading off of the switched side only pulls in the starter mounted solenoid to start the truck, nothing else should be hooked there.

Yep that is how its all hooked up. The alternator should be good though everything worked fine before i pulled it from the explorer. It seems like something on the alternator circuit is shorting to ground but i dont know what.

 

[flatblack]

check to be sure the charge wire isn't shorting from the alternator to the solenoid.
Unhook it from the back of the alternator and see if you get the same result, if you do then you have exposed wire in that line, let me know if this is the trouble I have one lying in the garage I'll never use you can have it.

 

[AZFX4]

So thanks to everyone for their help. I figured out the issue today. The wire that is hooked to the terminal on the back of the alternator was bent over and contacting the alternator housing and causing the issue. Here are a few pics. I went ahead and flipped it around so it cant do that again.

 

[yodaman1151]

so im working on an 86 with a 4.0 poorly wired in.... i have the newer alternator that has the two plugs instead of a lug. so the larger wires are supposed to run to the batt. side of the solenoid and the yellow/white wire goes to the fuse box (gets power)... the green/red wire is just snipped off. From looking at the diagram that gr/red wire needs to have key on power to turn the alternator on... correct?

 

[holyford86]

so im working on an 86 with a 4.0 poorly wired in.... i have the newer alternator that has the two plugs instead of a lug. so the larger wires are supposed to run to the batt. side of the solenoid and the yellow/white wire goes to the fuse box (gets power)... the green/red wire is just snipped off. From looking at the diagram that gr/red wire needs to have key on power to turn the alternator on... correct?

If you have two plugs and one has two large guage wires running out of it, you have the old style 2g alternator (external fan) if it has an internal fan and a lug on the back (as well as one plug to the regulator) it's the new style.

The old style alts with the plastic plug have been known to melt the plug out of them.

 

[yodaman1151]

I thanks I'll keep and eye out for that. By the way to get this truck to charge I had to put in a missing fuse, add about 4 ft of missing wire and move the solenoid lug connector up to the battery side not the starter side... I hate cleaning up after other people