Howdy,
OK, 2008 Ranger 2.3. Battery light on. Replaced bat. still on. Now this is where the delima starts.
The new bat. was under warrenty. alternator is also under warrenty. The problem is I can not change the part out. I have to get that done.
Thats going to around $150.00+-. If it WAS the alt. all is good. if not I'm out $150.00+-. Now after searching the many many forums, it seems
there might be a fuse(?) issue. Here is the problem. I have not found anything good on where those(some say 1 others say 2 or 3) not
mention the holy fusable link that nobody seems know where it is located. I've looked under the main fusebox(under hood). under the battery case.
I'm at a total loss. I would change it myself but being 75 and with COPD not so much.
Thanks in advance
Buddy

 

I'd test the alternator with a multimeter before proceeding any further. That is - if this is in your realm of doings and no bad intention or insult ment...

 

Already tested, when I got the bat. replaced. nothing comeing out of alt.

 

Sounds like you found your problem

 

Alternators need START UP voltage, the Battery Light is that start up voltage

In 2007 Fuse 9 and 10 in the cab fuse box power the battery light and startup voltage

No Battery Light with key on = no alternator

On the alternator are 3 wires, 2.3l only, V6 has 4 wires
Should be a 2 wire plug on the back of alternator with a Red and Grey(or green) wire
Unplug that connector
Red wire should show Battery Volts, always, not key on or off
Grey wire should be 0 volt key off, Battery Volts Key on, that 12volts is from the Battery Light on the dash, no 12v key on = no alternator

The larger red wire on its own should also show Battery Volts
If either Red wire is lower than Battery Volts then you have a blown Fusible link, these are near the battery/engine fuse box in the alternators wiring harness

Battery Volts = what the battery shows when tested directly
12.8 volt when new
12.3v when 5/6 year old


An alternator is similar to an electric motor, so if you leave it on all the time it will drain the battery
So it needs an ON/OFF switch, that's what the Battery Light circuit is for

If you just spin an alternator it won't generate voltage
It needs startup voltage, so it can "start" to generate voltage
The mechanical energy from the engine spinning it means it can generate MORE voltage than what is used to "start" it
The Rotor in the alternator is powered with 8.5 to 9.5 volts by the voltage regulator, which allows alternator to generate 13.5v to 14.5v

But to start making the volts it first needs that 8.5 to 9.5volts to send to the rotor, thats what the battery light circuit provides

 

Thanks for the great reply.
Alot of very good info, thank you, but I DO HAVE the bat. light. Plus everything elese works just fine.

 

If you test the 3 wires and all are reading correct voltage then Alternator is bad, 100% for sure

Charging systems are very very simple, 2 parts
There are the trucks wires to alternator(in your case 3 wires), and the alternator

If the 3 wires test as OK, then alternator is the issue, there is nothing else involved

Alternators can NOT be tested out of the vehicle by a Parts store, just FYI

 

OK, this is a never ending story ... I "Had" a bat. light (Key on) BEFORE I had the alt. replaced. Now I have "NO" bat. with key on. All of the other lights are on. But now still not charging. OK, now this is a 2008 2.3l. Your reply says 2007
I now feel that infact it might be the fuse(s). The problem I'm having now is know what fuse does what. In the 08 what are those fuses labled? Sorry to be a pain, but being 75 and on O2 it kinda hampers my fixing skiles.

 

In 2007 or 2008 Ranger check Fuses 9 and 10 in cab fuse box, both need to be good for Battery Light to work, to get alternator startup voltage

 

this is from my fuse guide. Inside cab right side passager.
9 = 5A Cluster air bag indicator
10 =10A Cluster (RUN/START), 4x4 module (RUN/START)
does that sound right?

 

Yes, that would be correct, cluster fuses

I don't think Ford ever labelled a fuse, or included in the description, Battery Light, lol, which is odd as its an important system, charging system

In a 2003 for example, its fuse 11
Description is
Instrument cluster, 4x4, Main light
switch, Truck Central Security
Module (TCSM), GEM

 

OK, first off, getting to those 2 fuses are a full time job on its own.
9 = 5A Cluster air bag indicator = unable to get to it to test, but I have BOTH airbag lamps on. (front and side)
10 =10A Cluster (RUN/START), 4x4 module (RUN/START) = test good

 

If a fuse was hard to get to then you will hate this next thing you need to do

2008 2.3l alternator has 3 wires connected
Larger Red and smaller red wires, and a Grey wire

The two red wires are connected directly to battery, via Fusible links, so should have Battery Volts all the time, if battery volts are 12.5v then thats what you should see on both Red wires

Unplug the Grey wire to test it
Grey wire should have 0 volts Key OFF
And 12volts with key ON, this is the ON/OFF switch for alternator charging and is also the Battery Light 12volts, AND the ground for battery light bulb


When the alternator/voltage regulator are off, engine off, the Grey wire is in essence a ground, so with key on the Battery Light gets 12volts from fuse box and is Grounded at the alternator so bulb lights up
But a light bulb is just a coil of wire that glows when heated, so the 12volt passes thru the bulb to the alternator's grey wire, that's the 12v you read with a meter when grey wire is disconnected and Key is ON
When you plug that Grey wire back into the alternator then its Grounded and Battery Light should come on, if key is still on
Its a pretty simple system

Now when engine is started that Grey wire supplies the alternators rotor with 12volts, called "startup" voltage that ALL alternators need
(if you were to leave "startup" voltage connected to alternator full time it would drain the Battery very fast, because rotor would try to turn the fan belt/engine, which of course it can't do, so dead battery)

Once the alternator is spinning, assuming startup voltage, it will produce 14volts
So fuse in cab(whole vehicle) now has 14volts, AND the voltage regulator and grey wire also has 14volts

What happens if a light bulb has 14volts on both wires?
Right, nothing happens, it can't light up because there is no voltage passing thru it, voltage is equal on both wires, so Battery Light goes OFF
If alternator should produce lower voltage than Battery(12.5v), the Battery light will start to flicker because voltage is now flowing thru the bulb, the lower the voltage at the alternator the brighter the battery light

So test the 3 wires at the alternator
If they test OK then alternator is bad, even if its new, its not at all a complicated system
3 wires is all there is

 

Sorry for the slow reply, so as I understand your last post is this.
"9 = 5A Cluster air bag indicator = unable to get to it to test, but I have BOTH airbag lamps on. (front and side)" so the 5 amp fuse is good, right?
Now the only way to test those wires is if the alt. is out. no way to get to the plug when the alt. is still attached.
Also I only 1 red wire connected to the pos. term on the bat.
What fuse does that gray wire run off of?

 

Grey wire is from the Battery Light in the dash, no other fuse but the ones in the cab fuse box that power the battery light

The two red wires don't have fuses they have Fusible links, short wires that are one gauge smaller than main wires they connect to Battery positive
Fusible links are like "slow blow" fuses, they can tolerate amp spikes that can occur in charging systems without "blowing", the wire and insulation on fusible links will melt and separate without causing a fire, lol

These are inside the wiring harness near where it connects to the fuse box, not on the alternator end of the wiring

Easiest way to test these is at the alternator end
Both red wires should have battery volts, key off or on doesn't matter

Grey wire should have battery volts but only with key on

Never work on the alternator of a 2.3l Duratec so not sure whats required to test those 3 wires
I do use sewing needles to pierce wires to test for voltage, doesn't hurt the wire or insulation
You can get "needle probes" for volt meters as well


Diagram below
Take note of the differences of the 4cyl. 2.3l and the V6 charging wiring, i.e. "except 2.3l"

 

first thanks for all the help. How hard is it to replace the Fusible links.

 

Easy to replace, hard part is finding them in the wiring harness

But TEST FIRST, very rare to blow a fusible link

The grey wire is most often the issue

But lately the "new" alternator is getting to be 99% issue, lol, read of people having to go thru 3 or 4 to get one that works
You can "bench test" an alternator is see if its OBVIOUSLY bad, but you can NOT test if its good that way, you can only test it in the vehicle to see if its good

That's why testing the 3 wires at the alternator is what should be done first
If the 3 wires test OK then alternator is bad, period, no maybe about it

 

Ok, I got 12.5v on the red wire to the plug. got 0v key off gry wire...got 12.5v key on gry wire. unable to get to red Bat. wire on back on alt.

 

The smaller red wire gets 12v thru the same fusible link as the larger red wire, so I would expect both fusible links to be OK
Per diagram in above post

Alternator is bad, 100%, not a guess