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Pavlin Koev
Pavlin Koev, CERTIFIED TECHNICIAN
Category: Ford
Satisfied Customers: 3425
Experience:  17 YEARS HANDS ON EXPERIENCE, TRUCK&COACH TECHNICIAN LICENCE
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1993 Ford Explorer: the battery and alternator..circuit..blown fuse

Customer Question

1993 Ford Explorer. We replaced the battery and alternator and it still does not charge the battery. We have checked every wire and connection in the battery charging circuit and cannot find a fault or blown fuse. The battery reads 12v before you turn the motor on, 11v while it is cranking the motor and back to 12v once the motor starts. We had the alternator tested and it put out 14.5v under load on the tester at Kragen and Autozone. A mechanic that has worked on it previously (put a new motor in it) said that he suspected the PCM. We cannot find a causative link between the alternator and the PCM that might regulate the output of the alternator to a lower voltage. Any idea why our battery might discharge over the course of a day or two of use?
Submitted: 3 years ago.
Category: Ford
Expert:  Pavlin Koev replied 3 years ago.

Pavlin Koev :

Hi and Welcome to Just Answer! My name is XXXXX XXXXX I will do my best to help.

Pavlin Koev :

alternator needs voltage to activate, just a minute to open wiring diagram

Customer :

Where does the voltage come from and at which pin on the alternator?

Pavlin Koev :

you need to have voltage on yellow white wire

Pavlin Koev :

all the time

Pavlin Koev :

do you

Customer :

`Where does it originate?

Pavlin Koev :

it comes from fuse 16-15A located in power distribution box

Pavlin Koev :

it has to be connected to A terminal

Customer :

We checked that fuse and it is good. With the engine not running we disconnected the connector and checked that pin and it read 12V.

Customer :

It is not possible to connect that connector backwards as it is keyed.

Pavlin Koev :

if this is ok, there is fusible link on the black orange wire between alternator and battery

Customer :

yes

Pavlin Koev :

have you checked resistance on that cable?

Customer :

We checked for continuity between the terminal on the back of the alternator (blk/org) and the connection to the starter relay and it was good.

Pavlin Koev :

can you use booster cable and by pass that cable

Pavlin Koev :

clamp on alternator where black and orange wire goes and the other end on battery positive

Customer :

We could try that but what will that accomplish?

Pavlin Koev :

if alternator is good and you have power to alternator, then it has to be that cable

Pavlin Koev :

it will not cost you to check

Pavlin Koev :

it will take few minutes only

Customer :

OK

Customer :

We connected the two and the voltage on the battery jumped to 13.5! I think we have our culprit!

Pavlin Koev :

ok, so you need to fix that fusible link or replace that cable

Customer :

We will replace the fuse link. Thanks. I suppose I hit accept now?

Pavlin Koev :

You are Welcome!


thank you for using just answer and accepting my answer


 

Pavlin Koev, CERTIFIED TECHNICIAN
Category: Ford
Satisfied Customers: 3425
Experience: 17 YEARS HANDS ON EXPERIENCE, TRUCK&COACH TECHNICIAN LICENCE
Pavlin Koev and 10 other Ford Specialists are ready to help you
Customer: replied 3 years ago.
Our problem continues. The Explorer battery went dead last night on the way back from his friends house. When we first ran the jumper to the back of the alternator the voltage across the battery jumped to 13.5V. But... while we were doing it I accidentally shorted the output terminal of the alternator to the body of the alternator and got a huge spark. After that we replaced the fuse link and the 8AWG wire from the starter relay to the positive terminal of the battery. The running voltage at the battery terminal was now 12.5V. It seemed to work fine until we ran it with the lights on. I think we nailed something in the regulator because it doesn't seem to put out enough juice to actually charge the battery. We're planning to pull the alternator and have it checked at NAPA where we bought it. It has a one year warrantee and if we don't tell them how we fried it, they may replace it under warrantee if it tests bad. Any thoughts on this?
Expert:  Pavlin Koev replied 3 years ago.
yes, they will replace it for you. also check if fuse 16 is not blown.
Customer: replied 3 years ago.

Is there another fee for this question or is this a part of the original issue and therefore covered under the original fee?

Expert:  Pavlin Koev replied 3 years ago.
no it is all good, it is still the same question
Customer: replied 3 years ago.
NAPA was great, they replaced the alternator without question. But, we installed the new alternator and we still have the same problem. It will start if we jump start the car. But within minutes the voltage on the battery begins to drop from 12 to 11.5 and so on. In a short while the engine just quits. The new alternator is not charging the battery. The F16 fuse (15A) is good. We are stumped as to what is causing the alternator to not charge the battery. For one brief moment the former alternator put out 13.5V when we had a jumper from the battery positive terminal to the back of the alternator and we haven't seen anything promising since then. Does the PCM have anything to do with whether or not the alternator will put out a charging voltage?
Expert:  Pavlin Koev replied 3 years ago.
PCM - no. check is the cable you installed with fusible is not damaged.
Customer: replied 3 years ago.
I created a new fuse link by crimping and soldering 2 12AWG wires to an 8AWG wire and crimped and soldered new ring lugs to either end (I design and build custom power supplies and test fixtures where I work). Then I replaced the fuse link with the new connection that I created. Then I replaced the connection from the starter relay to the positive terminal of the battery with a new length of 8AWG wire with the appropriate sized ring lugs at either end. Unless there is some sort of magic in a fuse link that should not be the problem. I'm suspecting some sort of loss on the ground side of the charging loop.
Expert:  Pavlin Koev replied 3 years ago.
check charging at alternator direct, check for 12V power supply at alternator plug.
Customer: replied 3 years ago.
We put the negative lead of the multimeter on the negative terminal of the battery and the positive lead on black/orange lead of the alternator and it read 12V, the same as the terminals of the battery. It's as though something has told the alternator to stop charging. The output at that terminal on the alternator tracks with the reading across the terminals of the battery. I tried one lead on the positive terminal of the battery and one on the alternator looking for a voltage drop which would indicate some sort of resistance in the line and there was 0 volts.
Expert:  Pavlin Koev replied 3 years ago.
is there a voltage on the wire coming from fuse 16, - try to remove black and orange wire and use jumper cable instead. let me know
Expert:  Pavlin Koev replied 3 years ago.
the wires you have created seams to be too small diameter and will load alternator and will damage it
Customer: replied 3 years ago.
OK. Well the Explorer is parked at a gas station about 10 miles from here at this time and we are charging the battery so that tomorrow we can at least bring it home. A full charge on the battery will get it about 20 miles before it just quits. We'll continue on this tomorrow, OK? I will check on the wire connected to fuse 16. Running a jumper cable to the rear on the alternator seems a little confusing to me considering that we have replaced both the black/orange wire (and fuse link) and the cable from the starter relay to the battery (with 8AWG wire). Isn't that tantamount to placing a jumper cable directly from the battery terminal to the back of the alternator? It now has all new wire and new heavy duty ring lugs in the charging circuit of the alternator. Is there some magic here that I am missing? The wires we used were 8AWG (55Amp capability) and 2 12AWG for the fuse link. That is the same as the original black/orange and gray wires it is replacing. The red wire from the starter relay to the positive terminal of the battery was 8AWG as well and we replaced that with an 8AWG wire as well. "too small a diameter" is a little confusing to me as current capacity for a given AWG is standard throughout the industry.
Expert:  Pavlin Koev replied 3 years ago.
Too small is the 12AWG you have used, but using small gage wire will not make a fusible link, fusible link is a special wire that will be 8AWG but will pop open if circuit current increases a lot. cable directly to battery is OK- just do not drive with booster cables as they may fall and cause damage. here is diagram for your alternator.graphic
Expert:  Pavlin Koev replied 3 years ago.
power at yellow white wire is needed to activate alternator windings. it is getting late for me, I hope you will be ok tomorrow, let me know. may not be abble to get back to you right away(busy at work) but soon as I can.
Customer: replied 3 years ago.
The schematic should be useful as well as the need to have a voltage on the yellow/white wire. We'll work on that as soon as we figure out how to get the hood open. When Nathan slammed the hood it looked a little crooked on the right side. We went to open it to correct it and the hood would not release. A friend of mine said we probably left a tool in there and that caused it to latch crooked putting pressure on the lock pin and preventing the release from working. Any thoughts on that predicament?
Expert:  Pavlin Koev replied 3 years ago.
try pressing hood down or seat on it as you try to pull the cable.
Customer: replied 3 years ago.
I was thinking of having Nathan jump up and down on it while I tug on the release. If he snapped the cable last night tugging too hard on a stuck latch, we are in big trouble. Won't be able to get to it until around 6pm or so. Thanks
Expert:  Pavlin Koev replied 3 years ago.
ok
Customer: replied 3 years ago.
We got the hood open by jumping on it while the other guy operated the latch. The question that keeps eating at me is this: Normally a fusible link is 4 gauge sizes smaller than the cable it is protecting. The wire coming from the back of the alternator is 8AWG and it connects to two 12AWG fusible links. Usually there would only be one 5 inch length of 12AWG fusible link to protect the rest of the circuit which is 8AWG. And yet both wiring diagrams that we now have show 2 lengths of 12AWG fusible link wire running in parallel. Standard 8AWG is rated at 55ADC. Standard 12AWG wire is rated at 30ADC. So in stead of protecting the wiring... well, I just don't know what it is doing. Tonight we plan to work on verifying that the yellow white wire is getting the 12.5VDC from the starter relay through the fuse panel. We didn't get home with the Explorer until after dark and I refuse to work on it in the dark. Too many things go wrong after dark. I'm hoping to work on it again tonight.
Expert:  Pavlin Koev replied 3 years ago.
OK, Let me know. the cable you made is good. you are correct 12 gage is good as long as there is good connection.
Customer: replied 3 years ago.
We confirmed the connection from the starter relay to the fuse (16) and from the fuse to the alternator yellow/white wire (and, of course, continuity in the fuse). Then we moved the black wire ring lug on the starter relay to the top of the stack. We started the engine and there was 13V at the positive terminal of the battery! That's a good sign as far as I know. It's not as much as on my truck (14.2) or my Tiburon (13.5V) but it's better than the 11.5 from yesterday. Hopefully this is fixed but I'd feel more comfortable with a solid 13.5V or better. Does the alternator/regulator put out a lower voltage if the battery is fully charged?
Customer: replied 3 years ago.
Also, I looked up fusible link wire. It's not just like regular 12AWG. When it gets to greater than the 30A rating of the 12AWG it melts in two like a fuse. The stuff I put in there will probably do 50A per wire without melting. Now the insulation will probably melt right off, but the wire will continue to conduct. Not good. Soon as I get a chance I'm planning to replace the standard 12AWG with fusible link 12AWG as a safety precaution. Thanks for all of your help.
Expert:  Pavlin Koev replied 3 years ago.
You are Welcome, thank you for using just answer!
Customer: replied 3 years ago.
It's back doing the same thing. It reads 11.5V at the battery terminals and will run out of power from the battery within a day or so. There's still something not working and I am at wit's end as to where to look next.
Expert:  Pavlin Koev replied 3 years ago.

alternator has all built inside, you install it and when you have all power and all attached according to diagram it has to work if your connections are good. if wiring is good check if alternator did got damaged during working process, there is nothing else. if you have overloaded the circuit you have blown the diodes in voltage regulator.

Customer: replied 3 years ago.
We are still dealing with this problem. The problem is that there is no 12V on the green wire that goes to the ignition switch. That wire provides the bias voltage to run the alternator. We connected a wire from the positive battery terminal to the green wire with a 500ohm resistor in series and the alternator began putting out 14.5V. The next morning the battery was dead because that connection should go to a switched source of 12VDC. We need to find out why the original connection to the ignition is not working or as a work-around we could possibly find a switched 12V source somewhere within the engine compartment. Right now we are using the positive coil terminal of the starter relay. That 12VDC is only available when the ignition is in the start mode and turns off when you let off the starter. It gets the alternator charging but with no bias supply to the regulator it does not regulate. That means we will eventually fry the battery by overcharging it, the very reason you need a regulator on your alternator. And the beat goes on...
Expert:  Pavlin Koev replied 3 years ago.
I am at work now, but will examine the wiring and get back to you a bit later, may be couple of hours. If you are talking about light green and red wire, this is the voltage that comes through charge light, not strait voltage should go to that terminal. you must wire up a bulb on the circuit. voltage goes through instrument cluster.
Customer: replied 3 years ago.
Actually, they have placed a 500 ohm resistor in parallel with the lamp in case the lamp burns out so that the alternator will still work even if the lamp is out. What this means is that we will eventually need to yank out the instrument panel and find out why there is no voltage at the alternator in spite of the 500 ohm work around. Maybe it got disconnected when Nathan was trying to fix the gas and temperature gauges. I personally don't care if the lamp works as long as the meter works. And the meter seems to indicate just fine as long as the alternator is charging.
Expert:  Pavlin Koev replied 3 years ago.
I think 500 ohm resistor is not needed. just solder a regular 12V bulb in series at that wire. then light will light up when ignition is on, and then voltage regulator must turn it off when starting to charge. use this as temporary fix until you fix your cluster.

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