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so I have a 1985 f150 xlt 5.8l v8, i wasn't getting any charge to the battery, so i replaced the battery, voltage regulator and alternator. I've tested the wiring from the alt to the relay at ignition, from alt to firewall, but from alt directly to voltage reg I get nothing, but resistance in the wire is fine. Any ideas? How can i find a wiring schematic? How can i tell the difference between 2bbl and 4bbl. Yes Im very new to working on my own car so Im just learning.
Hopefully my input is for the correct system. If you have an external voltage regulator, you need 12 volts to the Alternators "A" terminal and also to the "F" terminal. If this is not present the alternator will not charge. Disconnect the voltage regulator and jumper the A to the F terminal. This will full field the alternator and make it charge to capacity. Seen your other post seeking the wiring wiagram, wish I could help with that. It does sound like you have a wiring issue. Do this, engine off, is there 12 volts at A terminal of the alternator or test light on. If so, good, now start engine and with a jumper wire connect the A to the F at the alternator, it will charge now if alternator is good. Wish I was there with you buddy, this is an easy system to work on. Do not trust the gauge inside the truck use a voltmeter at the battery or watch for test light intensity to increase.
ok, so im basically bypassing the voltage regulator and telling the alternator to charge and this is a way of isolating the alternator to see if it charges? I'll give er a go and see how she goes. Fingers crossed this's been a long while tryin to fix,
Yes, no miracles intended, need to find out where we are. Three choises, alternator, regulator, or truck wiring. We will get thru this without a bunch of money spending, parts changing, trial and failure attempts.
Hey nzlogan/Good Old Bill, I don't mean to hijack this thread, but I am having a similar problem. I just picked up an '84 F150 yesterday, cheap. It has the inline 6. Everything works great, but it is not charging a lick. Had the alternator tested at O'Reilly's and it's fine, so I bought a new regulator and installed it. Still no charge. My father-in-law says that it has to be in the wiring, my dad says to check the fusable links around the solenoid first. What do you think? (What do any of you think, while we're at it?) You told nzlogan that his '85 was an easy system to work on, is my '84?
Comiehook, normally I would respond in a PM but am going to input here so another member can add to or correct me where I am incorrect. Has been no reply from nzlogan as to his outcome, such is the life of the forum.
Without the assistance of a wiring diagram my memory of the circuit is such. 4 wires at the voltage regulator. "A" goes to the alternator A terminal. "S" comes from the ignition switch. "I" goes to the indicator (light or gauge). "F" goes to the F terminal of the alternator. We need power to the "S" to close the regulators relay and put the 12 volts from the "A" wire to the "F" wire and excite the alternator. Its like foreplay, needs to be tickeled to put out. . Sorry, back to the real issue. We need 12 volts at the alts "A" terminal at all times, key on or off. When the ignition is on, 12 volts goes to the "S" terminal of the regulator, closing the relay and out to the "F" terminal of the alternator. Rotation of the alternator then increases the "A" terminals voltage and thus back to the battery thru the direct connection of the "A" wire. Hopefully this will help and please anyone, correct me where I am incorrect or put into words that are easier to understand.
ok, so i got the old girl going and this is what i did, no sweat hi jack away,
checked all voltage as good ol bill says, everything was fine i traced everything back and couldn't figure out what was wrong. So as GOB said first time i crossed the A and F terminals completing the circuit and exciting the alternator, wicked alternator goes, actually it charged to 15.7 volts go figure. So then i came back to my regulator tried grounding it not on the wall, nada. Ordered a new voltage regulator (another one) and replaced it...nothing. boo.
So get this I got the truck running and as it was running i pulled the S wire I beleive (basically the middle green one on the 85) and put it back in.. the system went. Dont ask me how completely confused but yeah it goes. More than likely for me dirty terminals, which seems strange on a brand new voltage regulator but there you go.
Oh and after all that two days later my solenoid went, ahahhaha. oh side note GOB is it bad to cross the solenoid to start it other than all the sparks
new here today, searched and read many threads, this one is very similar to my problem.
i have dad's old '86 F150 inline 6 4.9L with 76k, needed a new battery to get her here from up north, where she sat in a barn most her life.
battery was dead the next day, trickle charged to get it going, lasted a week/25 miles. dead again. pulled out the old alternator (not original). the boys at autozone sold me a new alternator, and switched out my old double pulley for the serpentine pulley that it came with, including internal voltage regulator. installed new alternator, ran great a few days/15 miles, then needed a jump, charged it up and took it to autozone
the boys there gave me this info:
battery was putting out 13V, motor not running
starter drew ~300A at ignition
battery/alternator put out ~16V motor running
told me that my system was overcharging. any ideas?