My alternator wont charge! please help!!!

[djimenzj]

454? stroked to a 502 maybe?

Hi everyone im new here! I have a 1970 GMC shortbed with a 454 or 502, the guy that I bought it from said it was srtoked to a 502? who knows? It drives great ecept for the fact that the f'NN thing wont fnnn charge!!! If I charge the battery it will only drive for 6 hours or so.

Specs=

externally regulated alternator new tested twice!

New power control module or whatever its called

the grounds are good too!

I checked the fuses and all of the harness has power and its not that bad in shape for its age.

What the f*** is going on please help???

My only theory is that im suppsed to have a wire going from the alternator directly to the battery??? am I right???

Thanks guys!

[68gmsee]

Here's a bump for you.

First, I'd check the wiring to make sure it's correct. If you replaced the alternator and voltage regulator and the alternator checks good, suspect the voltage regulator. I've had new defective ones. Also, they're solid state so if you have a short or wiring problem, you can easily blow one.

Someone here has wiring diagrams you can download, but not sure where they're at. Maybe a search on this forum for wiring diagrams would help.

[willyCJ]

So an alternator is pretty simple. There are only 2 (or 3) connections on most alternators.

The back of the alternator should have a 3/8" (roughly) bolt stick out of it. This is the charge line. It is typically connected directly to the battery or to another unfused hot connection (like the starting solenoid. Do you have any large (3/8" roughly lines coming off the back of the alternator?


If you have a large line on the alternator keep reading this:
To activate the alternator, you need a clutch wire. When this line drops below 12 (ish) volts, it tells the alternator to fire up and start charging. This typically hooks up with a spade connector. Some vehicles have the voltmeter gauge hook up to the alternator so it can test for failure.

[djimenzj]

Thank you 68 Gmsee! Thank you WillyCJ! I have not checked the voltage regulatror yet but I will tomorrow, as far as diagrams im more of a live picture guy,thanks for the tip!
WillyCY, where do I get a clutch wire? lol How do I install it exactly? Am I suppposed to add a wire going from the alternator to the batterty?

[mas09ts]

sounds exactly like what my problem was . . . the voltage regulator, replaced it and then ta da fixed. the old regulator's points were stuck open so it wasn't charging.

[djimenzj]

Thanks Mitch, I will keep you guys posted!

[willyCJ]

Do you know what a spade connector is? Most alternators have 2 spade connectors on the side. If the connectors aren't visible look for 2 roughly 12-18 gauge wires running to the alternator. If those wires exist, then you are likely okay there. If you only have 1 wire there, it may be on the wrong connector.

Do you also have a large gauge wire running off the back of the alternator?

I can't see in your picture well enough to figure out which wire is which. (sorry).

[VetteVet]

Here's a thread that may interest you guys.
http://67-72chevytrucks.com/vboard/s...d.php?t=119379

[djimenzj]

Thank you VetteVet! While reading the post the idiot light caught my eye which does not light up on my gauge cluster? Is that my problem? I also have a push start button wired up, my bro did it way before I bought the truck. VetteVet you bet Im going to do this conversion, I seen others that make it look like space work, or some crazy math problem, thanks!

[VetteVet]

Originally Posted by djimenzj

Thank you VetteVet! While reading the post the idiot light caught my eye which does not light up on my gauge cluster? Is that my problem? I also have a push start button wired up, my bro did it way before I bought the truck. VetteVet you bet Im going to do this conversion, I seen others that make it look like space work, or some crazy math problem, thanks!

I'm not absolutely sure but I believe the light has to work to excite the fields and turn on the alternator. The brown wire that comes from the idiot light runs to the voltage regulator and then a blue wire goes from the regulator to the alternator so that is the wire that lets the alternator sense the voltage in the system and tells the alternator to put out a charge. Did you say that the idiot light doesn't work at all. It should come on when you turn the key on and any time the alternator isn't charging. The bulb may be burnt out or you may have lost power to the light from the key switch. You need to solve this issue because you need the light to work if you convert to an internal alternator.

[Sinister]

I'm not so sure about the light being necessary. Mine's been missing the alt light since I've owned the truck, no problems charging.

[djimenzj]

I went to autozone, and the guy said I have a newer voltage regulator and it did not need to be repalced. I will now try the push start route and see if thats it,

BUT HERE IS MY QUESTION =

Do I need a POSITIVE WIRE going directly from the alternator to the TRUCKS BATTERY??? THANKS GUYS!

[djimenzj]

I dont have one at the moment and well it kind of makes sence to have it, or does it?

[Sport/Truck]

Originally Posted by djimenzj

BUT HERE IS MY QUESTION =

Do I need a POSITIVE WIRE going directly from the alternator to the TRUCKS BATTERY??? THANKS GUYS!

I believe so. Here's what I've got. http://www.boomspeed.com/bofh1968/ch...ng_diagram.pdf
s/t

[VetteVet]

Originally Posted by Sinister

I'm not so sure about the light being necessary. Mine's been missing the alt light since I've owned the truck, no problems charging.

I wasn't sure either but I know the brown wire has to have voltage on it so the resistance must come from the regulator windings.

obviously there has to be a path for the alternator output back to the battery.
The original truck wiring has the red wire from the alternator going to a splice that feeds the battery the regulator and the bulkhead connector.
The diagram below shows this. It is for a car but the only difference is the horn relay is on the inside of the cab on our trucks and it doesn't have a fusible link.

[djimenzj]

Thank you VetteVet, this confirms the truck is wired correctly when it somes to the atlternator, I will check the PUSHSTART button eventhough its just a two wire deal, one WIRE from the starter to the PUSHSTART BUTTON and the other from the fuse box to the PUSHSTART BUTTON,,, I will replace the IGNITION SWITCH and see what happens, im tierd of this ****!!! thanks for everyones advice! oohh I checked all the wires from and two the voltage regulator yesterday....

[Grapdawg]

I had the same deal and finally found that after I painted my block and all the altrenator brackets it stopped the alt from grounding through the block. I just took off everything and sanded of the paint at all contact points and it works fine now.

[Sport/Truck]

Originally Posted by Grapdawg

I had the same deal and finally found that after I painted my block and all the altrenator brackets it stopped the alt from grounding through the block. I just took off everything and sanded of the paint at all contact points and it works fine now.

Hmmm, I have powder coated brackets, painted block......I might need to grind some paint!
s/t

[Grapdawg]

Originally Posted by Sport/Truck

Hmmm, I have powder coated brackets, painted block......I might need to grind some paint!
s/t

No Im serious I hope your not making a joke of me because its true. I thought I was going crazy then I went to napa and had the alt tested and the guy grounded it to the alt were it had also been painted and tested bad. Then he grounded it to part of the test machine and bam it was fine. I spent 20 mins cleaning all spots that touched the block and also the bolts and washers. Fired it up disconnected the battery and she was still running. That was after I spent $20 on a volt reg and a hour and a half scrathin my head. So it may sound crazy but its true.
Cheers

[djimenzj]

well Grapdawg, I will try it even if doesnt make sence, lol but it does man, and my brackets are painted with like 5 coats of black high gloss paint,(IT WASNT ME) THANKS!

[Grapdawg]

Originally Posted by djimenzj

well Grapdawg, I will try it even if doesnt make sence, lol but it does man, and my brackets are painted with like 5 coats of black high gloss paint,(IT WASNT ME) THANKS!

Im tellin ya I thought the guy at napa was nuts but he was right because the alt grounds to the block via the brackets. there is no other ground on the alt. I just cleaned up the backside of the brackets that touched the engine and the engine also the bolts. Let me know how it goes.

[djimenzj]

Grapdawg, I will thank you!!!

[El Jay]

Bad grounds cause more problems on more stuff than you would ever believe; not just alternators.

[Grapdawg]

Originally Posted by El Jay

Bad grounds cause more problems on more stuff than you would ever believe; not just alternators.

Yep im finding that out one ground wire at a time. Never underestimate the POWER in a ground wire.

[El Jay]

Word! Up!!