Question about 1989 Ford F 150

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Electrical roblem my ford f-150 it a 1989 4x4 my alternator is good had it tested. the battery light is on the battery is not charging. if you take the neg cable off the truck shuts off. i changed all the ground wires on it. still not charging any thoughtd.

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  • 6 more comments 
  • Todd daley Oct 21, 2008

    thanks i will try it and see

  • Todd daley Oct 21, 2008

    tried a good battery still have the same problem any other thought for me to try

  • Todd daley Oct 21, 2008

    my alt has 2 plug ins the top plug has 12 volst in only one wire there is 3 it the bottom has no power to it

  • Todd daley Oct 21, 2008

    the large wire should it be on the back of the alt.i went out to my truck tonight took some readings with a good volt meter the numbers are as followes. with truck running battery 10v

    green wire 9v white wire0v yellow wire started at 8 v then droped to 3 v and stayed there .This is all with truck running.heater on lights on.

    then shut every thingg off tenumbers are as followes batterie 11v green wire 0v white wire ov yellow wire starts at 9v goes to 3v and stayes there. any thoughts

  • Todd daley Oct 21, 2008

    there is 1 hole that is threaded is that where the wire goes and if it does it go to the neg or pos side of the batterie thanks in advance.

  • Todd daley Oct 21, 2008

    so i should replace the wiring from the alt to the battery to try to fix the problem . there is no red wire running from the alt to the battery there is green white and yellow should i change these wires

  • Todd daley Oct 22, 2008

    hi guys thanks for al the info it is fixed to a point i can run the truck with the neg past off runns fine.iwent into the ab the volt meter in the truck now reads 0 the oil presure went to high but the battrie is now charging good how do i fix this prolem of the vols at 0 the oil pressure at high is it a fuse or some other problemit worked for a couple of mnuts i was petting in a new stero then i looked up the volt were at 0 the oil was at high the gas gage is good and the heat is fine also any thoughts

  • the_frog1469 Jan 04, 2009

    replaced the battery and starter/relay but still my battery wont charge



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How old is the battery it could have a bad cell that would cause this problem

Posted on Oct 21, 2008

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  • paul erickson
    paul erickson Oct 21, 2008

    with the engine off check to see if the batt terminal on the alt. has 12 volts to it

    its possible it burnt the link to the battery. let me know

    later paul

  • paul erickson
    paul erickson Oct 21, 2008

    there should be a large wire on a post held on with a nut

  • paul erickson
    paul erickson Oct 21, 2008

    Visually inspect the harness-to-generator connector for damage (heat, corrosion, distortion and cracking) Install the Generator Wiring Harness Connector Kit (E5AZ-14305-AA) if the harness-to-generator connector is damaged.
    the main red lead is the battery lead . and could be in the plug.

  • paul erickson
    paul erickson Oct 22, 2008

    The testing I did was just checking to see if the green redstripe wire delivered 0 volts with switch off, and 12 with switch on. Then I checked across the battery terminals. With everything off, got about 12.5 volts. With engine running, went to 14.6. When I turned on everything I could, like headlights, wipers, blower, radio, etc. Voltage dropped to 14.4 and stayed there. I would assume if yours is working properly you would see similar numbers.
    I think you have the 2g alternator. It is known to have problems due to bad connection thru the plastic plug. This has caused numerous fires. To avoid a potential fire

    so with that said buy the alt. harness it sounds like this is going to solve your problems

  • paul erickson
    paul erickson Oct 23, 2008

    lets star a new post

    this is a new subject ok



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Battery keps discharging

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.)))


((If all the above dose not isolate the actual issue, the likly culprit will be a drainage issue)).

Here is the procedure I use to isolate a battery drain. Remove negative battery cable from the battery. Using a 12-volt test light, hook one end to the negative battery post the other end to the negative battery cable you just disconnected. The test light will glow or "light" if there is a drain. If the "light or glow" is faint, that is probably normal draw for the clock or computer. If the "light or glow" is bright, then there is a large drain. That should be corrected. Now start removing and replacing the fuses one by one until the light goes out; that one will be the circuit with the drain. Remember to hold in the button in the door jam for the interior lights.

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