Finding a short?

[JadeCats]

Howdy y'all, Still running through electrical madness here, i got all my wiring figured out in the headlight system at last but I'm still running into problems. here's what ive got so far. 

My battery reads consistant voltage until i plug the terminals on to the posts, then it begins to drop. I'm assuming that this is caused by a short. I was told it was likely in my headlights system so i unplugged my headlight harness connector and it continued to drop. I recently did some work on the fuse panel side so i disconnected the connector on the firewall to the fuse panel to see if it was somewhere on the other side. The voltage continued to drop. 

I don't really know where to go from here and I'm not familiar enough with diagnosing electrical systems in general to make any sound guesses. Any ideas?

[Pete M]

I do believe there's a writeup on finding an active short in the link in my signature.   also a pdf of the electrical manual.

[JadeCats]

Quick update, i was messing around with some other connections and when i disconnected the battery positive from its direct line to the starter relay the voltage drop stopped, can i just eliminate this wire completely?

[omega_rugal]

no, but you are on the right track

[Jeep Driver]

23 minutes ago, JadeCats said:

Quick update, i was messing around with some other connections and when i disconnected the battery positive from its direct line to the starter relay the voltage drop stopped, can i just eliminate this wire completely?

The wire you are holding is your + feed wire. 

All circuits are fed off that wire. 

From the starter relay you see 3-4 wires feeding back into the harness. Those wires must be fused or protected, those short sections before the splices to the red wires are supposed to be fused links, those wires do NOT look like fused links.

If they are not fused links.......you have a truck fire in the making. 

[JadeCats]

5 minutes ago, Jeep Driver said:

The wire you are holding is your + feed wire. 

All circuits are fed off the wire. 

From the starter relay you see 3-4 wires feeding back into the harness. Those wires must be fused or protected, those short sections before the splices to the red wires are supposed to be fused links, those wires do NOT look like fused links.

If they are not fused links.......you have a truck fire in the making. 

I replaced the old crispy fusable link wires that were on it and i made sure that the new wire i used was fusable link wire of the appropriate guage, don't want to deal with another fire lol, if i have done something incorrect here i would appreciate any tips you have. 

[Jeep Driver]

3 minutes ago, JadeCats said:

the new wire i used was fusable link wire of the appropriate guage

You're good then. 

 

Install the feed wire as it was. Remove one fusible link at a time and test to see if you have a drop on any one of them....once you find it, you can trace that or those two circuits down.

 

Also, the glove box light is almost always the culprit......or one of them anyway. 

 

 

Also, you could have a relay that is stuck or bad, pull each relay and test for a drop there as well. 

[Jeep Driver]

Let me also add-

 

Check you ignition switch connector and also your headlight switch connector for any signs of burning/shorting. 

[JadeCats]

9 minutes ago, Jeep Driver said:

You're good then. 

 

Install the feed wire as it was. Remove one fusible link at a time and test to see if you have a drop on any one of them....once you find it, you can trace that or those two circuits down.

 

Also, the glove box light is almost always the culprit......or one of them anyway. 

 

 

Also, you could have a relay that is stuck or bad, pull each relay and test for a drop there as well. 

Would it have anything to do with interior if the main conector at the firewall is disconnected?

 

With the feed wire and both fusable link sets connected there is no voltage drop, it drops only once ive added back in the line from the alternator to the starter relay. 

8 minutes ago, Jeep Driver said:

Let me also add-

 

Check you ignition switch connector and also your headlight switch connector for any signs of burning/shorting. 

I recently changed the headlamp switch with no signs of scorching, but I'm not sure where the ignition switch connector is. 

[Jeep Driver]

5 minutes ago, JadeCats said:

it drops only once ive added back in the line from the alternator to the starter relay. 

Disconnect the alt and the drop goes away?

 

Sounds like you discovered your problem.

 

 

[JadeCats]

1 minute ago, Jeep Driver said:

Disconnect the alt and the drop goes away?

 

Sounds like you solved your own problem.

 

 

I'm not sure i understand, wouldnt that prevent the battery from charging? Where should the big line out of the alternator connect to? 

Forgive my ignorance, i appreciate the assistance. 

[Jeep Driver]

Just now, JadeCats said:

I'm not sure i understand, wouldnt that prevent the battery from charging? Where should the big line out of the alternator connect to? 

Forgive my ignorance, i appreciate the assistance. 

Based on what you said you discovered........your alt is the source of the short.

 

IOWs you have a bad alt. 

[JadeCats]

3 minutes ago, Jeep Driver said:

Based on what you said you discovered........your alt is the source of the short.

 

IOWs you have a bad alt. 

I'm not sure how that could be unless its a manufacturer defect, its practically brand new and not remanufactured. 

[Jeep Driver]

3 minutes ago, JadeCats said:

I'm not sure how that could be unless its a manufacturer defect, its practically brand new and not remanufactured. 

Connect the alt and you have amp draw.

Disconnect the alt and you have no amp draw.

 

Correct?

 

Is any thing else connected to the alt besides the exciter wire?

[JadeCats]

41 minutes ago, Jeep Driver said:

Connect the alt and you have amp draw.

Disconnect the alt and you have no amp draw.

 

Correct?

 

Is any thing else connected to the alt besides the exciter wire?

Thats right, and the only other wires from the alt are on the top end, one running to the oil pressure sensor and one to the distributor coil. The voltage still drops when that connector is removed with the alt still connected to the starter relay. 

 

Edit: 

Does it matter that my ground from the battery negative connects to the bolt on the alternator housing? Thats where the original was connected but ive seen some heeps connect that wire to the dipstick stud. 

[cruiser54]

The ground there should no be an issue. Good chance you have a faulty alternator. 

[Pete M]

it's a real shame, but these days just because a part is new doesn't mean you can assume it's perfect.    gotta test it. 

[cruiser54]

C.R.A.P.           Chinese Replacement Auto Parts

[JadeCats]

32 minutes ago, cruiser54 said:

C.R.A.P.           Chinese Replacement Auto Parts

Many thanks you guys, yall called it. I hooked up an old alternator i had lying around and experienced no voltage drop, seems like we'll be rolling again soon! Cheers!