1993 Charging Issue

[zombieologist]

Hi all!

So I bought a 93 ranger xlt for $600. It has a new alternator and battery in it, but it is still not working. I have seen the charging diagrams, but I cannot tell if I am looking at the right one or not. Can someone link me to the correct one and also kind of explain where each wire is and what I should be looking for? I have checked the inline fuse and it is good. I think there is something draining the power from the battery or something crossed, because I can charge the battery all the way over night and hook it up in the vehicle without starting anything and it will drain itself. I am confusing myself just typing this. Anyone run into anything like this before? Thanks!

 

[RonD]

You need a Volt Meter
Unhook battery and test its voltage
12.8v new, 100% charge
12.2v old 50% charge

But leave volt meter connected and watch voltage, if it is dropping while you watch it then battery has an internal short, replace it.

Hook battery back up.
Should be same voltage as when tested before, if it is dropping you have a big drain.
You need to start pulling fuses until drain stops, then check that circuit.


If you follow battery's positive cable it will go to Starter Relay post on fender.
There will be a few wires hooked up to the same post.
One will be a Dark Grey wire that is a Fusible Link, it will be a few inches long and then connect to a Black/Orange stripe wire, this wire connects to B+ on the back or side of alternator, the biggest wire on alternator.
A Fusible link is a fuse, but won't blow instantly with high amps, it will heat up and then if high amps continue(short) it will separate without causing a fire, so it is a type of "slow blow" fuse.

The other 2 wires going to the alternator are the Voltage reference wire and ON/OFF wire
"B+" wire is the charging wire, the output of alternator.
"A" wire(yellow/white stripe) is the voltage reference wire, in 1993 it should go to engine fuse box and be connected to 15amp Alternator fuse.
"I" wire(Light Green/red stripe) is the ON/OFF for the alternator, this wire comes from ignition switch via Battery Light.
Ignition switch--------battery light---------------------alternator "I"

An alternator is basically an electric motor used in reverse, so if left on it would drain the battery by trying to turn the engine via the fan belt.

So when you turn on the key 12volts goes to the battery light and it will come on if "I" wire is connected to alternator, because alternator is a Ground right now, not generating power.
This 12volts at "I" in alternator turns voltage regulator circuit on and it send voltage to rotor.
When you start the engine, alternator starts generating voltage, when that happens the battery light now has 12volts on one side and 12volts on the other side so with no Ground battery light goes off.

To test these wires leave key off.
B+ should have 12volts, if not check fusible link
Unhook 3 wire connector
"A" yellow/white stripe wire should have 12volts, if not check fuse
"I" Light Green/red stripe wire should have 0 volts, if it has 12volts then that is your drain, could be ignition switch is not cutting power or............??

Turn on key
"I" Light Green/red stripe wire should now have 12volts


The "S" wire is just a loop from internal voltage regulator to Stator section of alternator, this does need to be connected so make sure it is not broken or frayed at either end.

 

[tomw]

If you have access to an ammeter, you can disconnect the - cable from the battery terminal, engine off, doors not opened for 45 minutes or so allowing all the smart-stuff to go to sleep. Hmm. Well, give this a try any way as disconnecting might jar the smart stuff back awake.
Set the meter on the 10A setting, turn it on. Connector touch the red to the cable terminal, the black to the battery post. If you get a reading more than 250ma, you have something running, drawing juice.
I had a regulator fail, and feed 3A to the field coils in the alternator. Killed one battery after starting and driving into garage to do some brake work. I didn't know about the drain, and figured the battery had died. New battery, and all seemed fine. Next AM, down to 1.9V... Oops. This system had external regulator, and thus connection to the S & I external. Disconnect and the drain went away. Re-connect, and disconnect the regulator, and the drain also stopped. Looked at diagram. Only thing fed thataway was from the regulator, the O/B fat wire from the diodes that fed the battery and load had nothing to do with the regulator. Regulator fixed that. I didn't have any GEM or SJB to worry about, just the clock, radio mem, and computer mem, and they should not draw 3A.
tom

 

[zombieologist]

Hi guys, and thanks for posting. Sorry it took me so long to check it out. I have been swamped at work. Anyways, So I completely charged my battery. Then I tested it over and over while disconnected and it held voltage fine. I hooked it up in the truck. It didn't drop voltage. So, no drain. Then I checked the wires. All the wires check like they should, though I never saw a battery light anywhere. So I started the vehicle. The alternator was putting out 13.8v at first. Then at about 10-15 minutes in it dropped to 12 volts. It stayed at 12 volts for a while. The battery meter in the car never dropped and the battery stayed charged. So I decided to take it around the block. About 15 seconds into the drive, the battery meter started dropping. I pulled the car back in the driveway and checked the alt voltage again. It was around 11.8-12.1. It stayed like that. Then I had my wife come and press the gas to put a load on it. I had her hover at about 2000RPM while I checked the alternator. It started to fluctuate really bad. It would be at 11.5 and then drop to 5 or 6v for a few seconds and then back up for a second and then drop a few seconds more. When it dropped, it dropped anywhere from 3v-9v. Does this sound like an alternator? It is new and was tested to be good. Even after testing at AZ, could it still be the alternator? If not, where else should I check? Thanks!!!

 

[tomw]

There are two different alternator(at least, if not more) styles. One has an internal regulator, and the other external. If you have 3 terminals on the back side of the alternator, with three different wires, you likely have an external regulator, which can go bad while the alternator is fine. If you have one large wire to the alternator, and a connector on top where several wires plug in, you likely have an internally regulated alternator.
In the first case, you can replace the regulator for ballpark $20, more or less. You can test it but you'd need a VOM and the procedure to determine if the regulator has failed. I do not have it in my memory, and just follow the 'cookbook' steps in a shop manual trouble tree.
If the regulator failed as mine did, the battery will be discharged over night, and will have a current draw of 3A(approx) when nothing is going on.
Your alternator should be producing ~14-14.5 volts with the engine running. If you can, check the youtube for demos of failing and working alternators. See Makeuloco's work, that's what I watched for ideas.
tom

 

[RonD]

Yes, replace alternator

 

[enjr44]

Yes, replace alternator

^+one

Just like you said, it worked great for a short time (until it got hot??) so testing it for 30 seconds at Autozone probably would not be a lot of help.

New part doesn't mean good part anymore. They build it, put it in a box and ship it. You get to test it in the field. If it works great, if not bring it back and they will give you another one just like it (hopefully not just like it ).

 

[tomw]

Not a good working theory for such as the Escape/M/T trio. That alternator is hung on a fixture and the body and engine are installed around it. Swapping in a crappy rebuilt more than one time is not for the sane. I am not saying don't get a rebuilt, but don't purchase based solely on dollar cost. The things that go bad in an alternator are, mostly, the brushes, the bearings and the diode array. I'd bet a LOT of bearings out on the road are near dry. The diodes will work until they get a back EMF that cooks them or they have a breakdown and either short or open. The brushes will wear over time, but I'd say most will last close to 200k miles. A bad regulator can cook an alternator if it full fields it 100% of the time.
tom