unknown electrical problem

[globe471]

i need help with this "unknown" electrical issue on my 1978 datsun 620 pickup

have replaced the alternator and fixed the fuse box that needed to be replaced. 

all the fuses are new and have been replaced.all my gauges work and the engine runs awesome and strong after theses changes.the issue is that i recently replaced the battery because the truck was dying on me so i would have to push start the truck every time or get jumped, in order to get back home from where ever i was. i got tired of having to re-charge the battery once a week. [/color][/background]

i figured that the battery was no good and it seemed that the alternator wasn't doing its job even after i just put a new one on.

after i bought a new battery the issue went away for about a month and as of today the same thing started happening again. 

my battery is dead. its new. (now i have to charge itthe alternator is new.

the alternator isn't charging my New battery? WHY? 

i have mechanical skills but when it gets to the wire harness and wires, its a different ball game also seems that this happens mostly at night when the lights are on. (perhaps the lights are plugged in directly to the battery which drains it)

it seems to drain the battery. but not sure why my alternator isn't doing its jobLast night i was driving home with the lights on and eventually my gauge lights turn so dim that i could not see my speed, my turn signals stop working and then like never before, my truck starts sputtering so bad that it almost was impossible to drive, like a miss fire. could the lack of voltage make my truck misfire or sputteri guess the main question is why isn't my alternator re charging my battery, its newany advice or thoughts[url=http://www.northwestnissans.com/board/threads/143902-Datsun-620-unkown-electrical-issue?p=1936562382#post1936562382]http://www.northwestnissans.com/board/threads/143902-Datsun-620-unkown-electrical-issue?p=1936562382#post1936562382[/url

[flatcat19]

Break out your volt meter. Anything above 13.6V is charging.

 

 

Even new parts can be bad. Keep trying until you get one built by someone not having a bad day.

[datzenmike]

Clean and tighten the terminals and the posts. Now clean and tighten the other ends... The ground (negative) where it bolts to the head behind the fuel pump, and the starter lug on the starter.

 

Does the charge lamp light when you turn the key ON (not start) ... If yes, does it go out once the engine is started???? If no is the alternator two wire plug in firmly? Is the ground (Black) wire bolted to the case?

 

If yes, take the alternator back where you got it or somewhere and have it tested.

[globe471]

check to all your question King Rat.

all tight

the light turns on by just the turn of the key, and stays on for a few seconds after vehicle is started and it beaps for a few seconds then it goes away. 

My next question after playing with my volt meter; Anyone have a diagram of the main wire harness? 

[flatcat19]

Old Datsuns.com

[Charlie69]

Is the re a regulator on the inner fender well? 

 

Is the regulator plugged in?

 

Is the alternator an IR (Internally Regulated) alternator?

 

If it is an IR alternator the regulator should not be plugged in and there should be jumered terminals in the harness plug that connects to the regulator.

 

Pictures would help  copy and paste the img code after uploading your pictures to an online picture hosting sight such as photobucket.

[racerx]

I would make sure that my alternator is plug in really good, check your connections.  Had a similar issue back in the days and it was lose connection on alternator and to top it off my new voltage regulator (autozone) was defective.  I would get your alternator checked out at Oreillys or autozone, if good, get your DVM out and measure voltage across battery.  Measure when at idle, and should be little above 12 volts and when you or someone presses the gas and idles higher voltage should be close to 13 volts.  In other words you should see your voltage go up a little when revving up engine.

[racerx]

also check your belt, maybe it's too loose. Checked all of your connections.

[flatcat19]

Is the re a regulator on the inner fender well? 

 

Is the regulator plugged in?

 

Is the alternator an IR (Internally Regulated) alternator?

 

If it is an IR alternator the regulator should not be plugged in and there should be jumered terminals in the harness plug that connects to the regulator.

 

Pictures would help  copy and paste the img code after uploading your pictures to an online picture hosting sight such as photobucket.

 

78. Should be an IR set up from factory.

[datzenmike]

It does. All '78 and up Datsuns were internally regulated.

 

 

check to all your question King Rat.

all tight

 

Just to be clear, tight isn't enough. The contact areas have to be clean and corrosion free as well.

[globe471]

what does a voltage regulator look like?

i found this link about a voltage regulator from ebay. my engine bay doesnt have one of these?

http://www.ebay.com/itm/like/251635027480?lpid=82&chn=ps&ul_noapp=true

[datzenmike]

Don't worry your '78 does not have one to look for... read my last post. The '78 and up have the voltage regulator built right into the alternator. You won't find it.

[globe471]

im still not sure why it wouldnt charge my battery. 

everything is tight, corrosion free and new.

belts are tight but not to tight as should be.

connections are all tight

[globe471]

there is an extra prong on my alternator that isn't being utilized? does something go there that isnt connected perhaps?

[datzenmike]

Maybe post a picture.

 

You should have a two wire plug in the shape of a T. One (largish) Black wire (to ground the alternator) and one (largish) White or White/Red stripe going to the insulated terminal of the alternator output.

[globe471]

sorry about no pictures, photobucket wont let me in for some reason?

is there another way of uploading?

[racerx]

U have a volt meter? If you do see what voltage is a across battery terminal while car is at idle. If you dont have one, buy one at harbor freight. They are very cheap.

[globe471]

http://www.northwestnissans.com/board/threads/143902-Datsun-620-unkown-electrical-issue

i can upload pictures on here

[flatcat19]

im still not sure why it wouldnt charge my battery. 

everything is tight, corrosion free and new.

belts are tight but not to tight as should be.

connections are all tight

 

 

 

Again, even new parts can be bad. Quality isn't what it used to be.

 

 

 

there is an extra prong on my alternator that isn't being utilized? does something go there that isnt connected perhaps?

That extra spade on your alt is not needed and has nothing to do with your charging issue.

 

Grab the volt meter. Anything below 13.5V while running is bad.

My guess is you'll be around 11.5V when you check it.

 

 

No need to carry on until you check that.

[globe471]

i just tested my alternator with my battery charger with the alternator mode on the datsun, and and it read 0. no charge. 

i then quickly tried the same procedure on my brothers jeep and it said that alternator charge was complete and working. 

im taking it back to the auto parts since its  new

thanks for your time ill keep you updated on what happens next.

[Charlie69]

78. Should be an IR set up from factory.

After 30 plus years you can never be sure what is under the hood.

[datzenmike]

I can see an earlier one converted for IR but not an IR converted to external.

[Charlie69]

Yes it all depends on what is handy as to what some people keep their vehicles running with.  200 miles from there nearest parts house can be a game changer.

[globe471]

UPDATE:

THE GREEN MONSTER IS FIXED (Datsun truck name) !

They sold me a faulty alternator and it didn't work. i returned it and got a new one, installed it and that fixed my issues.

Thankyou for your help.

[racerx]

Yep...that happened before so now before i leave the store, i have them check the parts like alternator or starter.