hey guys trucks not charging, first bit of testing I did as outlined in the shop manual indicated the voltage regulator, so I replaced that, still wouldent charge so I checked all the wiring, found the alternator wire was burned, replaced that and inspected/ replaced as well all the other wires and the wiring harness its self. still wont charge. so as outlined in the thread "charging" I did as many tests as I could and for my wiring harness it says open A circuit, but I have already replaced that whole bit with 14 gauge from the alternator main wire/ bus bar to the regulator and 4 gauge from the alternator to the buss bar, could it possibly be an internal short in the alternator?

if all that is confusing ignore it and look at my test results please.

REGULATOR BYPASS TEST

1. disconnect harness and run vehicle - no change in voltage at battery= if voltage increased harness is shorted, should show base voltage.

2. jumper between A and F with I and S not connected to anything and run vehicle with loads on- A and F spark on contact, engine is started and voltage starts to clime (I stopped the test at 15V)= replace regulator

????? how would the regulator need replacing when I already replaced it and the test bi passed the regulator completly to begin with??????

3. connect F to Battery + run engine with loads on- 13.5V and climbing. =repair open in A circuit
????? I already replaced that whole wire????

WIRE HARNESS TESTS

1. connect jumper between battery + and alternator F and run engine- could not do, need jumper cables back from dad >

2. connect jumper between alternator case and battery-and run engine- voltage remains unchanged= next test, ground is good.

3. connect jumper between battery Alternator post and + on battery and run engine- umm this made a **** load of sparks, I didn't even start the engine.
?????? short in the alternator?????

all help and info is greatly appreciated thanks you guys.

 

If the field windings were shorted in the first alternator, and you replaced the regulator at that time, it will blow the new regulator.

Hook it all up normally. Get the engine running. You should have 12v on the "a" terminal, 12v on the "s" terminal, and see what you have on the "f" terminal of the regulator. The "f" terminal should have something, but it will vary depending on what the regulator is calling for the alternator to charge. The higher the voltage on the "f" terminal, the more the alternator will charge. That is why they told you to short the "a" to the "f". That will put 12v on the "f" terminal and throw the alternator into wide open charge.

Make sure the regulator has a good ground where it's mounted. If you have nothing on the "f" terminal as the truck is running, I bet the regulator was blown out by the old alternator.

 

just so I do all that correctly, hook the regulator up and all the connectors to it and measure whats happening to the A,S,F terminals while they are hooked up to the regulator and truck running?

 

well I got a new alternator and new regulator.
still wont charge

so either one of those 2 are bad or somethings messed.

just something I noticed, my battery warning light AND my oil warning light wont come on, normally I put the key in turn it 2 clicks and the break warning, emissions warning battery warning and oil warning lights would turn on then go out when the truck is started, now only the emissions and break light come on then go out when started.

my auto teacher says this might be causing the charging problem as the above light problem started with my sudden lack of ability to charge. (the only way I could tell that my charging system wasn't working was my voltmeter in the cab dropping from 14- 8 volts as the battery warning light never came on)

any thoughts?

 

Yes, your teacher is correct. The voltage from the ignition switch runs to the "bat" light in the dash, and then to the "s" terminal on the regulator. If you are not getting a 12v signal to the "s" terminal of the regulator, the alt will not come online and charge.

I had this problem on my diesel after I did the tranny swap, and come to find out I had dislodged the connector on the back of the instrument cluster when I had taken the dash apart.

 

so all I have to do is check and see if the connectors were knocked loose over a bump or something? and then re connect them?

at least I have a few spare parts now I guess as I cant return the regulators as I used them (already asked about that) and have 1 alternator that looks almost brand new, dont even know if I want to return it as I like the look over the old one (sigh )

silver lining, if this is the problem hopefully people will find this and check befor dropping 200$ and I needed to upgrade the wiring anyways as the alternator charging wire looked like 10 gauge and was burn at a splice. so I upgraded to 4 gauge and 1 gauge at the battery to the starter solenoid.