15 amp alternator field fuses keep popping

[Paisano]

Hello,

1992 Ford Ranger XLT with 2.9 V6. My voltmeter was showing low voltage at 12 volts with the battery warning light recently. I smelled electrical burning one time. I replaced the voltage regulator (and brush assembly) because my multi-meter indicated a low reading. It didn't fix it. Then this weekend it was popping 15 amp 'alternator field' fuses. Now the truck won't start. It just cranks. I checked engine bay and crawled under truck, I did not find any exposed or damaged wires.

A few troubleshooting questions.

1. Is it is safe to disconnect alternator and fuse and see if truck will start?

2. Is it true you can use a compass to find a wire fault?

3. Will bad alternator keep truck from starting altogether?

 

[SenorNoob]

1: It should be ok as long as all of the connections to the starter are properly connected/insulated to/from each other/everything else. That's the tricky part.

2: I can't see how that could work on DC. Especially in the crowded area under the hood of a truck. Lot's of moving electricity and metal parts to confuse the needle.

3: Only if it's shorting a necessary circuit, (anything else on that fuse or other fuses blown), keeping power from reaching a necessary circuit by some form of open, or the engine and starter are small enough to be held in place by the serpentine belt. (Don't laugh, it happened to a 92 Saturn that my mom had once.)

 

[Paisano]

I was reading the wrong position on the fuse box chart. It's the engine compartment lamp fuse that popped.
This makes sense too because the engine bay lamp has not worked for a few years. The 15 amp alt field fuse is fine.

I'd like to start some troubleshooting tomorrow night on the no start condition. I'm replacing the alternator either way because of the low voltage reading, age, and some melt damage on the fixed connector plug. I'm concerned about alternator hookup from lack of color coded wires and decreasing reach of engine bay wire length over past alternator wire splices

But some diagnostic first.

 

[Paisano]

I got the old alternator off. Should I wire it like this?

connect heavier gauge orange and blue stripe engine bay wires to either new alternator solid black wires (interchangeable) ?
and connect single narrow gauge black and green engine bay wire to new alternator narrow gauge white wire?

 

[Eddo Rogue]

I'm used to it done the other way around. Start the truck and disconnect the positive cable from battery. If truck dies, you have bad alternator. If truck still runs, alternator is good.

 

[Paisano]

what about the wiring?

 

[Paisano]

I am working on these problems now over the weekend. I read the wiring diagram in my Chilton Manual.
I also had a discussion with the alternator manufacturer this morning on wiring. I wire it like I did back in 2017. I will report back later.

 

[Paisano]

I repaired my truck yesterday on both counts. The new alternator fixed the low voltage issue. And the no start condition was caused by the fuel pump not engaging. The fuel pump fuse was in the wrong slot and using one of the wrong amperage also. I corrected this and it started right up.
I'm not sure if the transmission repair place was messing with the fuses earlier this year, or if I did this a few days ago when I was checking for blown fuses. They altered my negative battery cable for some unknown reason back then, which I immediately corrected. Thanks