I have received this list for several months and have found many interesting facts and answers. It has been my pleasure to be a silent participant to such an interesting and friendly group of people.
I am asking for some help regarding my 67 F100. I replaced the alternator today and afterwards the alternator light has come on and stayed on. I am positive unless I'm wrong that the wires were put back in the same terminals they were removed from. I have the wiring diagram and have found all the wires. What I'd like to know is what exactly am I looking for to be wrong. Would this be a wiring fault, a voltage regulator fault, or something else.
The alternator was checked at parts shop and is working properly. This is an 300 inline 6 with no frills. If someone could offer me some insight and direction with this I would appreciate it.

Lee W. Klughers
Raleigh, NC

 

First, have a buddy apply muscle to tension the alt. and belt while you tighten it in place. My 68 F100 with 360 V8 was a bear for one person to do, it always required 2 of us. I'll bet doing so takes care of your light. If not, take the truck to a reputable station, mechanic have them check that the alt. is charging the battery with the engine running. It's not uncommon to occasionally get a weak rebult alt. from the parts house.

 

Did you replace the alternator because the alt light was on???
If I remember correctly if the light is on it means the alternator is not putting out more voltage than the battery's level.
You can check this with a voltmeter. Connect the leads to the battery and check the voltage, it should be around 12 volts. Then start the truck run it at about 1500RPM you should read about 2 volts higher than the battery. Turn on the lights and heater the voltage should drop but either recover or stay at least 1 volt above the battery.
If you dont have a higher voltage with the truck running. Check the alternator belt for condition, it shouldnt be cracked or real shiney, and you shouldn't be able to press on it and get more than 1/2" deflection in the centre of the belt between the pulleys.
If the belt is tight and ok. Check all the electrical connections for corrosion and tightness. You can also measure for battery voltage at the BAT terminal of the alternator and on the yellow wire to the voltage regulator, if it is not present repair or replace the wire from the starter relay.
If they check ok. Make sure the regulator is grounded. You can either clean the mounting base and mounting area to bare metal around the bolt or even better connect a jumper wire from the regulator case to the negative battery terminal. Also make sure the alternator case is grounded. Usually this is accomplished by the mounting bolts to the engine block, but it never hurts to clean them up or run a ground wire direct to the battery negative.
If it is still not charging. Take the regulator out and get it checked, it is usually no cost at most shops.
However, if the voltmeter reads 2 volts above the battery (about 14volts) and the light is still on. I would suspect a defective voltage regulator, as it turns the light on and off. Or it could be a short from another circuit feeding voltage to the light circuit.
Hope this helps and let us know if you find the problem.

 

Thanks for the help and tips, I also checked into the archives and followed up on advice there. After replacing the regulator twice and alternator twice and removing and checking the battery problem was finally found. Quoting from my original post, "I am positive unless I'm wrong that the wires were put back in the same terminals they were removed from." Well I was way wrong. Ground to field, stator to ground and field to stator. I would have felt much worse about being such a dope if I hadn't been so relieved about solving the problem.
Was back and forth to Advance Auto and the guys there were great testing, checking, general support and time.
Thanks again for everyone's help.
Lee W. Klughers
Raleigh, NC

 

I got it running like a champ, timing was just a hair to retarded