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So I got a alt. from auto store, put it in, things ran fine. Then the gen light glows & flickers sometimes, as well as
the headlights & interior lights both went from bright to dim...loop....loop. Then sometimes not. So I replaced the
VR with a new one from auto store. Away went the dim to bright....loop, as well as the on & off GEN glow. Then I noticed a screeching sound from under the hood & worsened with rpm increase. Checked belt, was tight enough but worn, stiff & cracked, so I replaced at auto store. The alt. spins freely with no bearing noises(but outter cup of pulley saw bent & wobbling when spun). No shaft play... as goes for the water pump.

Drove away from auto store & noticed the crazy dying sounds were louder & the truck died a few times. Pulled back in to the parts store & the belt was being torn from the outsides thanks to the ALT pulley. The inner cup portion of the pulley had seperated from it's other half and moved & spun about freely. So store exchanged alt & belt. I installed correctly. Go to start & it starts with a high idle, GEN light on solid, wants to die, dash lights are 10X brighter then ever seen before, then it dies. Store employee said it was my VR, but I explained I bought it from then 1 day prior & switched with the old one to prove otherwise. He has his tester & said it's(ALT ?) putting out, but I'm getting 18vdc & that's too much. No kidding.....

So my truck sit's in their parking lot & I have 1 day to fix or move. Any ideas or words of advice please? It's a stock 1980 2wd

Alternator makes voltage, voltage regulator regulates it...

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FIAA!

SFPP!

Is it possible for either my HL or IGN switch to create this problem?

You would have to a have a major ground problem to make it do that...voltage regulator.

i agree voltage regulator...
if you keep running it like that you will start to smell an eggy/sulfur-ish smell when its running... which will be your batteries water boiling out... get a voltage regulator asap
happened to mine. took 5 mins to swap regulators and been fine since

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I replaced the VR 3 day's ago... one day before this happened. The alt. was tested at oreilly's & they said it passed, but couldn't run a rectifier test. I thought that was internal on the alt? The F(field wire) get's 7.8 vdc & nothing at N(field return/ground). A is at 16-18.4 vdc. resistance test between F & N = OL (open circuit). Anybody know a way to bench test the VR? the resistor spec's for the two under the VR?

Voltage regulators are adjustable. They work by rapidly cutting the field in and out. I am not sure what the resistors on the under side do, or what value they should. It still seems to me that if you erplaced both the VR and the alternator you need to look elsewhere. With the ignition on and engine not running, check the output side of your fuse box. I know you said you cleaned it, but it could still be a problem. I soldered the pieces together on mine years ago and none of electrical problems since.

getting 11.90 output from fusebox. traced all the wires in the charging circuit except the white w/ red stripe one for the fuel pump relay & gen lamp. What has me confused is the auto parts store has sold me bad stuff before, they don't always test properly & the alt has an issue. When the feild coil is fed 12 volts, I get no voltage from the field coil ground terminal. this shouldn't be right.

Ok, I checked. On the 6 wire plug from the VR white red = W = fuel pump and charge light, white = W = ignition, white blue = B = battery, black = E = earth, British for ground, white black = F = field, the stem of the Tee connector to the alternator, and white green = N feeds back to the VR.
With the engine running I have 15 volts on the white and white black and 7.5 volts on the white green wire.

A year or 2 ago, my alternator quit. Dug up the 10 year old reciept and went to AAP. It took 3 alternators before I got one that gave me the 7 volts on the white green wire.

Maybe I need to adjust my VR before I am buying new headlights and battery. Checked the battery water last night,and it was fine. I just changed the oil and was finishing up checking things.

Had the same problem and did the same steps u did but i got 3 bad v/r in a row untill i got a good one, so keep working on v/r you will get a good one soon enough. i believe your supposed to get about 14 volts out of it, no more. i had one that ran 17volts one ran 18 and one was like 11 lol all over the place.

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So the alt was tested again, then by me again & it passes. I just hope that there isn't some kinda short that could be messing up the VR return line(N)_stator, to the VR from Alt tee clip. Also I checked the white ign wire & the white w/ red one too. The fuel pump relay get's power & GEN light goes off if the VR is unplugged. I wonder this thought: My backup lights don't work. The bulbs r good, just no voltage to them. I get 11.5vdc before the b/u switch & 9.2vdc after the switch. I have power to point where wire goes under pass. underside. Is it normal to lose 2ish volts on a reverse switch?

Remove both bulbs then check voltage again, before and after the switch. Replace one bulb at a time and see if they light up. It sounds like too much of a drop if your bulbs are good. Even at 9 volts the bulbs should light up although dim. Could be dirty switch contacts causing the problem.

I think the alternator can put out voltage with out the 7 volts on the white green N wire. If so, the VR may increase the field raising th evoltage too high. Check for voltage at the alternator plug and VR plug. Could have an open. Or even the contact inside the VR.

The voltage readings r the same. There are 2 switches on the gearbox. 1 is backup lights & the other is a coasting richer? The wires are nasty & the one that is off the side(driverside) was finger tight, very lose & had gearoil that went all over the place. Damn lube shop didn't either tighten it enough or the vibrations lossened it.

With the bulbs removed you should have the same 12 V on both in and out of the switch. If not you have a load somewhere, probably the wire shorted to ground. I would check both sockets carefully and any wiring, connectors, etc at the rear of the truck, up behind the bumper. Concentrate on anything somebody else installed like a trailer plug or something.

That switch might be causing your problem because it uses the transmission case to ground the circuit!

Got the b/u lights working. Found where someone wired in tow lights & cut the tie in's off, leaving heavy gauge wire uncapped under the chassis frame. Now noticing when driving at night, that when I use the right turn signal, the GEN light comes on dim to the pulse of the flasher. But this doean't seem to happen for the left/blinker.

I wired in newer style 2 way bulb sockets. Is it possible that they have a higher amp rating then what the system can handle? Or could wiring the bulbs differant create this?

Even the largest turnsignal bulb is nothing compared to the headlight. I think you still have more ratting out bad connections, and I am not convinced that lemon juice is the commplete cure for the lousy fusebox. If you have the same size bulbs left and right, no shorts, and good connections, it shoudl be the same left and right.

Agree: Make sure you have the same type bulbs, left and right , front and rear. Check the brightness of each as it is possible to install a double filiment bulb wrong if you try hard enough.

The 2 way lights on the front are not stock, but are both the same. They are from a 2000 mustang. The rear is all stock. But I might have got the hot wires mixed up as say.... 3 wire socket. Black is ground, then 2 hot wires, one for running lights, one for blinker( If the hot wires are not on the exact same filaments to luminate, could that be a problem? Also, My driver side headlight is cracked glass all over with clear tape over it & looks like alot of moisture got in there at one point. Could that be a problem?