The yellow wire in your Alternator plug Have a "Fuse Link" at the
starter relay. If that fuse link is bad the alternator will not charge.
To test jump the yellow wire with the hot wire at the alternator and if
the alternator is new it should charge. Check and install the fuse
Other details that you can try:
First ensure your battery terminals are clean and free of
corrosion. Make sure you use a battery tool to clean them up to ensure a
good connection. reconnect and tighten.
NOTE: Some electrical systems need to have the system computer reset
after changing an alternator. If you changed the battery first, then
changed the alternator, this may not have happened. Sometimes it's as
easy as fully disconnecting both terminals and reconnecting the battery.
Check the voltage from the positive terminal of the battery to the
negative terminal on the battery(record this).
Then check voltage from the positive terminal of the battery to where
the negative terminal connects to the block. if this reading is lower
your negative battery cable may be the problem. I've had them
crystallize before from age so badly that they lost flexibility and
began breaking internally. Replace it.
Then check voltage from the smaller positive cable post on the
alternator and the negative terminal on the battery. If this is lower
the smaller cable may be the problem. Replace it.
Then check voltage from where your positive cable hooks up to the
solenoid and to the negative terminal on the battery. if this is lower
your positive battery cable may be the problem. Replace it.
Charge the battery fully and take the vehicle to a local auto parts
store and see if they can run a charging system test (usually a free
service). They should be able to tell you what kind of shape your
battery is in and the alternator output. A good alternator will put out
14+ volts, if it's putting out 12-14 volts it's wearing out and needs
If your alternator is putting out 10-10.5 volts or less means one of the
diode pairs are bad, 5-5.25 volts or less 2 diode pairs are bad. Either
way the alternator is not charging the battery and it's the fault of
the voltage regulator.
Ask the person doing the test if he can tell you what the field voltage
is on the alternator. If they can and it is around 12 volts or more you
can probably bypass the next test.
Start the vehicle and hold a steel tool near the back of the alternator
(not on the pulley side). It should be drawn magnetically to the center
of the alternator. If it doesn't your alternator is not generating the
magnetic field needed, to generate electricity. This could be due to a
bad alternator or wiring.
WARNING: The next test is the "old fashioned" way we shade-tree
mechanics used to do this. It can be done with the engine running in
most cases, but you must be extremely careful that you don't get
clothing or long hair anywhere near the pulleys. You do this at your own
risk. If you are uncomfortable with taking such a risk, have your
mechanic look into it. Disconnect the two wire box-like electrical
connector from the alternator's voltage regulator and see if there is
any voltage (should be around 12 or more volts DC) from the wires going
to the alternator. You can try testing this with the engine shut down
and the key on, but it may not work on all vehicles.
With connector disconnected, if the voltage is less than 12volts or
non-existent, it's a wiring problem. - With connector disconnected, if
it is 12 volts or above it's probably the alternator (Bad windings.)
Set the multimeter to Ohms. Touch probes together and calibrate the
needle to zero on right side of meter readout. (If the needle does not
move to the right, you may need to replace the meter's battery or fuse).
With the Alternator connector disconnected check the resistance of the
alternator at the connector blades. If the needle goes to infinity,
there is an open circuit in the windings. Replace the alternator.
Other things that can cause charging system problems:
- Excessive starter draw - Remove starter and take to parts
store for testing
- Bad solenoid
- Failed engine compartment fuses or resisters - Look for and
check big rectangular ceramic ones as well on antique/classic vehicles
- Failed fusible links
- Failing ignition switch - Usually under the dash, Not at the
- Wiring to the key assembly inside the steering column - or on
the dash older vehicles
- Bad computer modules
- Electrical wiring - This one takes the longest to isolate
- Particularly hot wires arcing to ground
- Some other Windstar threads suggest checking wiring bundles
under the rubber boots at door hinges.
- Other unassociated electrical components shorting to ground
and placing a drain on the system - could be anything from a cigarette
lighter, to lighting, to electric radiator fans failing to shut off,
ignition coil, radio, sensor probes shorting to ground, etc. etc
Hope this help (remember rated and comment this).