2008 2.3L Alternator problems!! Please help!


08ranger2.3l

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Hi Guys, I am hoping some of you can chime in on a problem I am having. I have tried searching the forum but have not been able to find a solution.

Truck Info:
2008 Ranger XLT
Super cab, 2 door
2wd, Manual trans
2.3L Duratech
182XXX miles
Purchased used 6 months ago

Short version:
Step1: My alternator went bad, it would only charge after revving over 3000 RPM. No alternator light was on.

Step2: Replaced with refurbished alternator from Advanced auto. It then would charge, but the alternator light was on. Was told that it was probably overcharging.

Step3: Replaced with a new refurbished alternator from Advanced Auto. Same deal as the first one: was charging, but the alternator light was on.

Step4: Returned alternator to Advanced, replaced with a refurbished unit from Performance Auto. This one does not charge and the alternator light is on. Took the alternator to the parts place and it tests good.

Step5: Ohmed all of the wiring from the regulator plug to the fuse box (two wires), the ground from the block to the battery, and the charging wire from the alternator to the battery. All checks out OK.

I am at a loss and do not know what to do now. I thought that perhaps one of the great guys at TRS could shed some light on it for me....

If you want the in-depth story, here is a short book about the situation:

About 3 months ago I started to notice a charging problem. The alternator would not kick in and charge unless I would rev the engine to over 3000rpm. I ran some leads into the cab and hooked up an analog multimeter so i could watch and see when the alternator would kick in. The alternator/charging light never came on. The previous owner had mentioned that he had just replaced the alternator about 2 months before i bought it.

I continued to drive the truck like this for a couple of weeks until i had the time to replace it.

I purchased a refurbed alt. from Advanced Auto Parts and swapped it out. I started the truck, the alternator immediately kicked in and was putting out 14.8V. I thought "Great!" until i noticed the alternator/charging light was on... I made a couple of calls to my mechanic buddies and they said it is not uncommon to get a bad refurb and it was probably over charging, causing the light to come on. I pulled the alternator back out, called Advanced and had them order me another one.

The new alternator came in, i returned the one that was causing the light to come on, and proceeded to install the second refurbed alternator. This alternator had the same problem as the other. When i went to pick this one up, i had the guy at Advanced put both the one i brought back and the new one on the tester. They both made voltage, which is all the tester looks for to determine if it is Good or Bad. The guy did admit that it does not check to make sure the regulator is working or not.

By this time i am very frustrated. I pull the alternator out again, returned it for a full refund plus my core, and went to the other auto parts place in town (Performance Auto) who carries an alternate brand. The ensured me that this brand completely rebuilds the alternators, including replacing the regulator. This is why they carry that specific brand. I take it home, install it, and get absolutely nothing from it. It does not charge and the light is still on. I pulled it out again, took it to advanced and had them test it. It makes voltage on their tester.

I am now at a loss. I do not know if i should pull it out and get another replacement, or cut my losses and take it to the dealer. I have ohmed out the regulator plug to the fuse box, the block to the neg. battery terminal, and the positive battery terminal to the wire that connects to the charging post on the alternator and they all check out good.

I apologize for the book, but i thought it was better to give you all of the info up front.

Thanks for any help you guys can give, you are awesome!
 


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RonD

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The Battery Light is the ON/OFF switch for the alternator.
An alternator is similar to an electric motor so if left ON when engine is off it will drain power from the battery.

On the alternators regulator wiring the light green/red stripe wire will be the wire that goes to the Battery Light.
The other terminal on the battery light goes to the ignition switch(key)
The 3 wire connector on the alternator often gets frayed wires, check them carefully, make sure contacts are clean and tight.

A light bulb works, glows, when power is passed thru it, so if I have 12 volts on one terminal and 0 volts on the other terminal power will flow thru the bulb and it will glow.
If I have 12 volts on one terminal and 12 volts on the other then no power passes thru the bulb so it doesn't glow.
That is how the Battery Light works.

When you turn the key on 12 volts(battery voltage) runs from ignition switch to Battery Light, then thru the battery light to the alternators voltage regulator which has 0 volts if alternator is not spinning, so Battery Light is ON.
When you start the engine the alternator starts generating power so it is no longer 0 volts, the system voltage is now the same on BOTH terminals of the Battery Light bulb so no power is flowing thru the bulb, it is OFF.
If alternator is generating less than 12volts(battery voltage) then Battery Light will come on because power is flowing thru the bulb, 12v(battery) on one terminal and less than 12volts from alternator on the other.

Measure battery voltage with Key off
Should be 12.2v to 12.8 volts
Below 12.2v means battery is getting near end of life, 5+ years old
2008 vehicle may still have original battery, if voltage is 12.2v or lower I would change it.
Best time to test battery's "true voltage" is after it sits overnight.

Start engine, battery voltage should now be above 14volts but under 15volts, alternator is recharging battery from starter motor use.
This should last 3 or 4 minutes depending on battery condition.
After initial recharge Voltage regulator should set voltage at 13.6volts, this is maintenance charge for battery, it is not recharging and not discharging, 13.5v to 13.7volts is fine.
Turn on head lights, voltage at battery should drop and then come back up to 13.6v
Turn heater fan to high, same thing should happen, voltage drop then back to 13.6volts
This is the voltage regulator working as it should.

If voltage at battery stays above 14volts then voltage regulator is not working or engine off battery voltage was below 12.0volts or you have a blown fuse in Power Box, check each fuse with ohm meter, visual doesn't always work.

A voltage higher than 15volts at battery will also cause Battery Light to glow, the voltage regulator circuit won't go higher than 15volts so above 15volts in the system means power is passing thru the Battery Light bulb so it glows.
 
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08ranger2.3l

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Thanks for the info RonD.

At this point the truck has been sitting for almost three weeks, and the battery is at 12.6v. The battery looks to be fairly new, and i believe the original owner mentioned having it replaced a few months before i bought it.

When the original alternator was still in the truck, it would not charge the battery until i revved the engine to above 3000rpm's, then it would continue to charge the battery until i shut the truck off. During this, even when it was not charging (12.6V read at battery, slowly falling as it was not being replenished) the battery light never came on. This did not seem normal to me.

My regulator plug has three pins, but there are only two wires going to it. Is this normal? I have ohmed from each of the two pins on the plug back to the fuse box and get approx. 15 ohms on each wire. This seemed ok to me but i am FAR from an expert.

I have visually checked the fuses, then ohmed them, then replaced them. I wanted to rule it out, even though each of my checks showed that they were ok.

With the first two replacement alternators, the voltage was always at 14.8, even after driving 15 miles to my buddies house. That is why we thought the regulator was not working correctly.

I am trying to figure out what could be keeping the alternator from charging the battery, even though it does make voltage at the autoparts store. Is there something in the ECM that turns it on instead of just the ignition switch? I have never heard of that before, but thought it was worth asking...

I ran into an issue on a 90's Camaro once, where Chevy had used a special alternator for a few months production. None of the alternators i bought would work for it, until i purchased a "special" one from the dealer. It took three weeks to get and cost about $600, but it worked where none of the others did. Does anyone know if Ford has ever done something like this with the Rangers?

Any comments or other things to try would be greatly appreciated.
 

08ranger2.3l

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Any other ideas or things to look at? I am at a lost guys and could really use some help.

Thanks!
 

RonD

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OK, finally found a wiring diagram of what I hope is a 2008 Ranger 2.3l alternator and charging system.

Yes only 2 wires in the connector and then the B+ larger Red wire

With Key off you need to test both RED wires on the alternator, the large one and the smaller one in the connector.
Both should show 12volts(battery voltage)
Both have their own Fusible Link, not a Fuse, but a short wire that "acts like a fuse", these will take higher fluctuations in amps without "blowing", but they can fail.

If either shows no voltage, from Red wire to ground then it's Fusible link is blown.
Smaller wire has a Fusible Link B, 18gauge
Larger Red wire has a Fusible link A, 10gauge(both red wires use this one)

3rd wire should be Gray
It should have 12volts when key is on, this is the wire that turns on the alternator, the 12v comes from the key switch thru the battery light.


Also read something that I didn't know.............some of the newer charging systems used the PCM(computer) to do "smart charging", not all that sure on what that means, but if you have a "smart charging" system then all bets are off, lol
 
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08ranger2.3l

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Thanks RonD! I will check that out tomorrow (hopefully) and let you know how it works out.

Where did you find the schematic? I have not been able to get my hands on one.
 

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A cheap DVM is your friend.

Lead acid battery is 2.2 volts per cell. 6 cells - 13.2volts.

If your battery is below 13.2 volts then either it is severely discharged or one of the cells is dying. First thing is to pop the cell covers and make sure there is water covering the plates. Second is to make sure your battery terminals are clean and tight. Batteries usually have a peel-off purchase date - they don't last more than 5 years or so.

Also make sure your alternator isn't slipping.

If your alternator is working, it will attempt to charge the battery by raising the voltage you measure (between the battery terminals) to around 14 volts, maybe a little higher. If the voltage remains at 13.2 volts (or lower) then your alternator is bad.

A dead cell in a battery can effectively over-power your alternator - so don't hesitate to replace the battery.
 

RonD

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In theory a battery cell will have 2.2volts, actual new battery voltage will be below that.
12.8volts is more accurate when battery is new, this is "at rest" voltage, tested at least 3 hours after engine has been shut off..

To maintain a battery's charge you need to send it 1volt above it's "at rest" voltage, so an alternator/regulator will usually set voltage at about 13.6volts

To recharge a battery, like after starting engine, alternator/regulator will send it 2volts above "at rest" voltage so about 14.6volts


Good read here in battery voltage and what it means when testing:
http://www.therangerstation.com/Magazine/Fall2008/truck_batteries.htm
 
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dla

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In theory a battery cell will have 2.2volts, actual new battery voltage will be below that.
12.8volts is more accurate when battery is new, this is "at rest" voltage, tested at least 3 hours after engine has been shut off..

To maintain a battery's charge you need to send it 1volt above it's "at rest" voltage, so an alternator/regulator will usually set voltage at about 13.6volts

To recharge a battery, like after starting engine, alternator/regulator will send it 2volts above "at rest" voltage so about 14.6volts


Good read here in battery voltage and what it means when testing:
http://www.therangerstation.com/Magazine/Fall2008/truck_batteries.htm
It's not theory - a charged cell is 2.2 volts or greater. I.e. a charged battery is at least 13.2 volts. 12.8 volts is a discharged battery. 12.2 volts is a suspect battery.

Kind of important because a bad battery can easily make your alternator look bad.
 

08ranger2.3l

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Thanks for the help guys! I finally got a chance to get out there and look into it. The red wire on the alternator regulator plug did not have 12V. I checked the fuse link but it was good. There must be a break in the wire somewhere in the harness. I opened up the harness under the truck, where it passes under the trans. No 12v on the wire there either, but i did have continuity between that point and the plug.

I ended up running a new hot wire from just after the original fusible link, across the engine compartment firewall, and spliced into the wire about 3" from the plug. Crimped, heat shirnked, and taped all the connections and i am back up and running! Feels good to have the Ranger back, especially with a new semester starting next week. I couldn't afford another semester driving my Chrysler back and forth to school, the gas was killing me!

Again, thanks for pointing me in the right direction. You guys are the best!
 

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Your alternator did not go bad.

Many late model Fords have what is known as a self-exciting alternator.

Basic operation of a charging system in late model units, about 2004+ is that the system is more or less computer controlled. The PCM monitors the system and tells the regulator what to do, along with providing the wake up and B+ to get started. In a traditional system the alternator needs that B+ to start making power.

With a self-exciting unit it retains enough residual charge after power is shut off that if the engine is revved above 3000 RPM it can start charging on it's own. Once the fault is detected the regulator defaults to 13.5V. In fact the best test of a late model Ford alternator is to unplug it, rev the engine up, and see if it starts kicking out 13.5.

After that the PCM monitors system voltage and tells the cluster to turn on the battery light if voltage goes below 11 or above 15.


You never did have a problem with the alternator. You probably have an intermittent wiring issue somewhere.
 

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Your alternator did not go bad.

Many late model Fords have what is known as a self-exciting alternator.

Basic operation of a charging system in late model units, about 2004+ is that the system is more or less computer controlled. The PCM monitors the system and tells the regulator what to do, along with providing the wake up and B+ to get started. In a traditional system the alternator needs that B+ to start making power.

With a self-exciting unit it retains enough residual charge after power is shut off that if the engine is revved above 3000 RPM it can start charging on it's own. Once the fault is detected the regulator defaults to 13.5V. In fact the best test of a late model Ford alternator is to unplug it, rev the engine up, and see if it starts kicking out 13.5.

After that the PCM monitors system voltage and tells the cluster to turn on the battery light if voltage goes below 11 or above 15.


You never did have a problem with the alternator. You probably have an intermittent wiring issue somewhere.
I read about the "smart charging", but I also read that Ford didn't use it on every model consistently, some had it some didn't, even in the same model year???

Is there a way to ID a Smart charging system vs a standard charging system?
And is it strictly PCM or is it part of another module?

I found this diagram of a 2008 Ranger charging system: http://www.justanswer.com/ford/75f0m-ford-ranger-2008-ford-ranger-battery-light.html

Scroll down.
It lists a "Smart Junction Box" with 2 fuses, but looks like a standard charging system other than that, i.e. the battery light voltage turns on alternator(I) connection on regulator.
 
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Matty2.3ranger

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I have a 2001 2.3L 4 cylinder Ford ranger and my truck started acting all crazy one night like the battery symbol came up and I could barely give it gas mabey 40mph but if I tryed going any faster it would bog out then It stalled and tryed starting it back up wouldnt crank and I left my phone at the house so I had to walk 12miles home at 1130pm -530am to my house then wait till 9 to retrieve the truck and any how I got the truck back and would run bog down then when I cranked it this time battery symbol still on dash lights flickering .charged the battery put it back up and did a test took the negative off the battery the truck died instantly so I knew it was the alternator I took the alternator to advance auto and they tested on their machine and it came back that the alternator was good it passed the test i thought to my self how the hell is an alternator with 150000 miles on it still good the store clerk assured me that the machine that test the alternator was brand new and never fails so I said screw it i bout a new alternator put it on and my truck ran better.reply back to me iff u need help with ur ford ranger I know quite a bit about these trucks
 

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welcome to the Ranger station. according to rumors there are a few ranger experts here.

friendly FYI, you just replied to a 5 year old thread.
 


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