Alternator not charging battery on 2007 f-150. zero ohms between battery negative and alternator housing. battery voltage at positive terminal on back of alternator. battery voltage at red wire of three prong connector on back of alternator.

this is a volt/ohmmeter.
an "Ohm" is the measurement of resistance in a circuit. ...ie, a wire going from point A to point B is what you would call a short circuit.Sometimes wires are supposed to be connected directly to another point, therefor that is a short circuit on purpose. If the same wire was cut between point A and point B, then that is what is referred to as an "OPEN" circuit, and the ohms would be very high like infinite. OHMS in a short circuit would be measured as 0 (zero).

Voltage in a house is called ALTERNATING current, or AC. Voltage in a car is called DIRECT current, or DC.
Always make sure you select AC on the meter in the range of higher than what you're measuring. ...ie house uses AV120volts, therefor the meter should be set to 200, or anything higher than 120.

Set the meter to 20volts DC when checking a car, which uses 12v DC.

If you want to see if your car's alternator is charging the battery, select DC voltage (20 Volt range) on meter and place positive (red) probe on POS (+) on battery, and place negative (black) probe on NEG (-) on battery. The meter should indicate 12Volts DC if the car is off. The meter should indicate somewhere around 13 or 14 volts DC if the car is running and the charging system is functioning properly.

happy troubleshooting!

Your charging system is not working correctly. Unlike most other vehicles, the alternator in yours does not have a built in regulator circuit. Some troubleshooting must be done to find the defective component. Most of this can be done with the vehicle still assembled.

First, check that you don't have a blown fusible link. In most newer cars, these will be in the underhood fuse panel, and look like giant fuses. If good, you will read very nearly zero volts and zero ohms when measuring between the positive battery terminal and the alternator output terminal. If either measurement doesn't read zero, find the loose connection, bad wire, or blown fusible link.

Next, check the ground connections to the engine, battery, and car body to make sure you don't have a bad wire or connection somewhere. Again, measure voltage and resistance between the negative battery terminal and all associated grounding locations. For a quickie test, you can rig a jumper cable between the battery negative terminal and the alternator case. If there is a spark when you make the connection, you have a bad ground somewhere.

If your battery is well connected to the alternator, the problem may lie in the control circuit. Most Chrysler alternators have two control wires that control the field coil. Some control the battery current and have constant ground supplied, and some have battery voltage applied and control the ground current. To test, disconnect the control connector and measure the voltage of both terminals with the ignition in the "off" and "run" positions. Make a chart of each terminal and its corresponding voltage.

Start the vehicle and measure both terminals again. If the terminals tend to be zero volts, except when the vehicle runs you have voltage on one terminal, you have a system where the computer controls battery voltage. If the terminals tend to be 12 volts when the ignition is on, then one terminal goes low when the engine runs, the computer controls ground current. If the voltages of one terminal change but not the other, this suggests a bad computer.

To do a go/no go test of the alternator unit, you can connect the control pins on the alternator with the control connector disconnected. Simply connect jumper wires to the two control terminals of the alternator. Connect one jumper to a known good ground, leaving the other jumper loose. Connect a voltmeter to the battery terminals or to the output wire on the alternator. Start the vehicle and briefly connect the second jumper wire to the positive battery terminal while watching the voltmeter. While the jumpers are both connected, the battery voltage should rise dramatically.If it doesn't, this suggests a bad alternator.

If all this sounds too complicated or dangerous, a good mechanic can perform a similar diagnosis in under an hour with definite results. Good luck.

Hello! An Inlet air temperature sensor is used to calculate the temperature near the battery... This temperature data, along with data from monitored line voltage (battery voltage sense circuit), is used by the PCM to vary the battery charging rate... This is done by cycling the ground path to control the strength of the rotor magnetic field... The PCM then compensates and regulates generator current output accordingly to maintain system voltage at the targeted system voltage based on battery temperature...
In simple terms the inlet air temperature sensor is defective OR the ground from the negative battery terminal is NOT at zero ohms from terminal to chassis and from terminal to engine block...Check with an ohm meter set on X10 scale (bare metal) of chassis and engine block to negative battery terminal...Must read zero ohms...If not install ground straps...
Inlet Air temperature sensor ...See picture below...Is a low cost item <$10...It has 2 wires in its connector ...Colors are...Black/Red and Black/Light Blue...It is located in the tube leading to the air box...

STANDARD MOTOR PRODUCTS Part # AX112


Guru..saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

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 links.

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 replaced.


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 key
• 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).

Bad battery.

How is the pigtail ground strap from engine block to body? Have you had engine diagnostic test done? Voltage rVOLTAGE DROP TEST
A voltage drop test is the only effective way to find excessive resistance in high amperage circuits. It's a quick and easy test that doesn't require any disassembly and will quickly show you whether or not you've got a good connection or a bad one.
To do a voltage drop test, you create a load in the circuit that's being tested. Then you use a digital volt meter (DVM) to measure the voltage drop across the live connection while it is under the load. Voltage always follows the path of least resistance, so if the circuit or connection being tested has too much resistance some of the voltage will flow through the DVM and create a voltage reading.


If a connection is good, you should find little or no voltage drop and see less than 0.4 volts for most connections, and ideally less than 0.1 volts. But if you find more than a few tenths of a voltage drop across a connection, it indicates excessive resistance and a need for cleaning or repair.
CHECKING THE STARTER CIRCUIT
To check the starter circuit for excessive resistance, you need to measure the voltage drop at the battery, battery cable connections and starter while the engine is being cranked.
The first check is "available battery voltage." For the starter to crank at normal speed, the battery must be at least 75% charged (12.4 volts or higher). Low battery voltage can not only affect the starter but every other electrical system in the vehicle.
A. Set your DVM to the 20 volt scale, then connect meter positive (+) lead to battery positive (+) post (not the clamp or cable), and the meter negative (-) lead to battery negative (-) post.
B. Disable the engine so it will not start when it is cranked. (Ground the ignition coil wire, or disable the ignition circuit or fuel pump relay.) Limit cranking time to 15 seconds or less.
C. While cranking the engine, record the volt reading on the DVM. D. Next, connect your meter positive (+) lead to the battery terminal stud on the starter, and the meter negative (-) lead to the starter housing.
E. While cranking the engine, record the volt reading.
F. Compare the two voltage readings. If both are the same, there are no excessive voltage drops on the positive feed side.
G. If available voltage at the starter is not within one (1) volt of battery voltage, there is excessive voltage drop in the circuit.
The next test is for voltage drop on the positive side of the starter circuit.
A. Make sure the battery is fully charged.
B. Disable ignition.
C. Set DVM on 2 volt scale.
D. Connect meter positive (+) lead to positive (+) battery post, and the meter negative (-) lead to the battery terminal stud on the starter. While cranking the engine, record the voltage reading.
The maximum allowable voltage drop including the solenoid or external relay in the starter circuit should be 0.6 volts or less.
If you find more than a 0.6 volt drop in the starter circuit, you can isolate the bad connection by using the following voltage drop tests.
* Check the positive battery post and cable connection by measuring the voltage drop between the two while cranking the engine. Connect the meter positive lead to the battery post and the meter negative lead to the cable clamp. A good post/cable connection should have zero voltage drop.
* Check the positive battery cable by measuring the voltage drop end to end while cranking the engine. Connect the meter positive lead to the clamp on the positive battery cable, and the meter negative lead to the end of the cable at the starter. Crank the engine and note the voltage reading. A good cable should have a voltage drop of 0.2 volts or less.
* To check the starter solenoid or relay connections, connect the meter positive lead to positive battery terminal on the solenoid or relay, and the meter negative lead to the starter motor terminal. Crank the engine and note the reading. A good connection should have a voltage drop of 0.2 volts or less.
Next, you need to check the negative side of the starter circuit. To check the entire circuit, connect the meter positive lead to a clean spot on the starter motor case and the meter negative lead to the negative battery post. Crank the engine and note the reading. The voltage drop on the negative side should be 0.3 volts or less.
If the voltage drop is too high, set your DVM to the 2 volt scale and start checking each connection on the negative side to find the bad connection or cable. Use the DVM leads to check across each connection while cranking the engine as before.
Check the negative battery post/ground cable connection (should be zero voltage drop).
Check the negative ground cable from the battery to the engine (should be 0.2 volts or less).
Check between the negative battery post and starter housing (should be 0.3 volts or less).
Check between the engine block and starter housing (should be 0.10 volts or less).
CHECKING THE CHARGING CIRCUIT
To check the alternator connections on the positive side for excessive resistance:
A. Set DVM on 2 volt DC scale.
B. Connect the meter positive lead to the alternator output stud (B+ terminal).
C. Connect the meter negative lead to the positive (+) battery post.
D. With the engine running at 1,800 to 2,000 rpm with all lights and accessories on (except the rear electric defroster), check the voltage drop reading. It should be 0.5 volts or less. If higher, the connections between the alternator output stud and battery need to be cleaned. Also, look for loose connections or undersized cables.
To check the alternator connections on the negative side for excessive resistance:
A. Set DVM on 2 volt DC scale.
B. Connect meter negative lead to alternator case.
C. Connect meter positive lead to battery negative (-) post.
D. With engine running at 1,800 to 2,000 rpm with all lights and accessories on (except rear defogger), check the voltage drop reading. On the negative side, it should be 0.2 volts or less. If excessive, the connections need cleaning or the negative cable needs to be replaced. Some alternators are mounted in rubber bushings and have a separate ground strap. If so equipped, be sure to check the voltage drop across this strap, too.

egulator checked with voltmeter?

There seems to be a no charge state in this case. i recommend checking the charging system. use the procedure below to isolate this issue.

Wear protective eye wear and clothing and remove all jewelry when checking your battery and charging system. Jewelry is a good conductor of electricity and is not recommended. Most batteries wear out every 3 to 5 years and need to be replaced. Always replace your battery with an equal replacement battery to assure proper operation. Automotive batteries have a +positive terminal (red), - negative terminal (black). Electricity is stored in the battery and then supplied to the vehicle when the engine is not running. While the engine is running the vehicles alternator charges the battery for future use. (Note: never disconnect the battery while the engine is running. If the battery cable is disconnected from the battery a spark can be generated which can cause the battery to explode or a major electrical malfunction to occur.)

To check a battery surface voltage, remove the positive terminal protective cover. Connect the +positive side meter lead (red) to the positive side battery terminal. Connect the - negative (black) side meter lead to the negative battery terminal. With the vehicle not running and the car sitting over night the battery voltage should be between 12.5 and 12.8 volts.(You will need to use a voltmeter for this testing procedure)

The alternator is rotated by a drive belt driven by the vehicles engine while it is running. Electrical voltage and amperage are generated to recharge the battery and supply voltage to the electrical system of the car. The alternator is held in place with mounting bolts. There is a main electrical wire on the rear of the alternator that supplies voltage to a main voltage junction box. If your alternator is not charging properly, your battery will slowly drain down from operating all the electrical systems in your car and stop the car from running.(most non charge states will be the cause of a loose belt or a low tension rate, due to a mis-adjusted alternator. make sure you have enough tension in the belt for full rotation of the alt pulley)

Next, you will need to check the alternators output with the Amp meter.

Testing the amperage output of the alternator is good for measuring the amount (not the level) of voltage the alternator can produce. This test can be tricky because if the alternator is weak it can still show it as producing amperage. Which is good, but if the voltage is low, it will still allow the battery to go dead. To check the amperage output of an alternator an amp meter is needed. Once the meter is connected start the engine. Next turn on all electrical accessories and raise the engine idle to about 1200 RPM. The alternator should output the max amperage it was designed to produce. Example: a 90 amp alternator should output about 88 amps. Note: An alternator cannot sustain maximum output for long periods of time. If the alternator is forced to operate at maximum output it will overheat and fail. An alternator is designed to operate at max amperage output only for a reasonable amount of time.

((Connect the voltage meter lead the same way you would in a battery static voltage check, Start engine (do not drive) at engine idle the voltage should be between 13.6 to 14.3 volts. If not the alternator may need replacing.)))

Ok, i understand that you have replaced the alternator, but there seems to be a non charge state in this case. i recommend checking the charging system. use the procedure below to isolate this issue.

Wear protective eye wear and clothing and remove all jewelry when checking your battery and charging system. Jewelry is a good conductor of electricity and is not recommended. Most batteries wear out every 3 to 5 years and need to be replaced. Always replace your battery with an equal replacement battery to assure proper operation. Automotive batteries have a +positive terminal (red), - negative terminal (black). The battery in this illustration has a protective cover over the positive terminal to prevent short circuit in case of an accident. Electricity is stored in the battery and then supplied to the vehicle when the engine is not running. While the engine is running the vehicles alternator charges the battery for future use. (Note: never disconnect the battery while the engine is running. If the battery cable is disconnected from the battery a spark can be generated which can cause the battery to explode or a major electrical malfunction to occur.)

To check a battery surface voltage, remove the positive terminal protective cover. Connect the +positive side meter lead (red) to the positive side battery terminal. Connect the - negative (black) side meter lead to the negative battery terminal. With the vehicle not running and the car sitting over night the battery voltage should be between 12.5 and 12.8 volts.(You will need to use a voltmeter for this testing procedure)

The alternator is rotated by a drive belt driven by the vehicles engine while it is running. Electrical voltage and amperage are generated to recharge the battery and supply voltage to the electrical system of the car. The alternator is held in place with mounting bolts. There is a main electrical wire on the rear of the alternator that supplies voltage to a main voltage junction box. If your alternator is not charging properly, your battery will slowly drain down from operating all the electrical systems in your car and stop the car from running.(most non charge states will be the cause of a loose belt or a low tension rate, due to a mis-adjusted alternator. make sure you have enough tension in the belt for full rotation of the alt pulley)

Next, you will need to check the alternators output with the Amp meter.

Testing the amperage output of the alternator is good for measuring the amount (not the level) of voltage the alternator can produce. This test can be tricky because if the alternator is weak it can still show it as producing amperage. Which is good, but if the voltage is low, it will still allow the battery to go dead. To check the amperage output of an alternator an amp meter is needed. Once the meter is connected start the engine. Next turn on all electrical accessories and raise the engine idle to about 1200 RPM. The alternator should output the max amperage it was designed to produce. Example: a 90 amp alternator should output about 88 amps. Note: An alternator cannot sustain maximum output for long periods of time. If the alternator is forced to operate at maximum output it will overheat and fail. An alternator is designed to operate at max amperage output only for a reasonable amount of time.

((Connect the voltage meter lead the same way you would in a battery static voltage check, Start engine (do not drive) at engine idle the voltage should be between 13.6 to 14.3 volts. If not the alternator may need replacing.)))

Make sure you have 12 volts going to the ALT. If not you have a popped fuse or open wire.

First, check battery post to cable connection: positive meter lead on battery positive post, negaitve lead on battery's positive cable clamp. Crank the engine and note the reading. A good connection should have zero voltage drop. Second, check the positive cable: positve meter lead on positive battery clamp, negative lead on starter terminal connector. A good cable will show a voltage drop of .2 volts or less while cranking. Third, check the starter connection: positive meter lead on positive battery terminal on the solenoid, negative meter lead on actual starter stud. A good connection will have a voltage drop of near zero volts. Now to check the negative side of the circuit. Total drop on the ground side should be .3 volts or less and can be checked by placing positive meter lead on starter housing and negative meter lead on battery ground post. Take your reading while cranking the engine, and be sure your connection at the starter is solid and clean. If total voltage drop on this side of the circuit is excessive, complete testing at all connections in the same fashion as the positive side of the circuit. Check the following: between battery post and clamp (zero voltage drop), cable end at battery to cable end at engine. (.2 volts or less), cable end at engine to engine itself (near zero voltage drop), and finally between starter housing and engine block (.1 volts or less).

To read the entire procedure for all automotive systems read this artile:
http://www.engine-light-help.com/voltage-drop.html