Charging Issue

[Zombro]

Hi er'body.

 

So after I rebuilt my motor, it hasn't been charging, just running off the battery.

 

What I have done so far...

 

Thought it might be the alt, so I swapped it for another out of my parts truck. Still only getting like 11.5 volts.

 

Took old alt to advanced to bench test and it failed. Got it Rebuilt by the best shop around, still only reads 11.5 volts.

 

Inspected the fusible links on the positive. it was kind broken but still did its job, but I replaced it anyway. Still nothing.

 

Wire to alt seems fine.

 

 

Where should I check next? Really sucks having nothing wrong on the truck but the charging system. Maybe I can install a solar panel and then just drive a couple miles every hours or so.

[ggzilla]

What you should do next is test the wiring to your alternator. Check and see with KEY ON, are you getting 12V at the S terminal of the alternator? If not it won't charge.

 

Also check your CHG lamp on your dash. If it is burnt out the alternator won't charge. You might be tempted to run out and buy a new bulb, but instead try to test it:

* KEY ON, engine not running: CHG lamp should light up

If it doesn't, the wiring connection may be bad between the lamp and the L terminal of the alternator.

[elmerfudpucker]

+1 ggzilla! and also make sure the connections for your grounds are clean and tight!

[Zombro]

Ground is nice as hell.

 

Which is L and Which is S?

 

Holding the alt where the pins from a T. Which is horizontal and which is vertical.

 

Thanks for the response. the Light stays on so it not burnt out but, I will check that too when I get my multimeter back tomorrow.

[datzenmike]

Look at it as a T ... now which is horizontal and which is vertical?

 

On the 720 the horizontal White wire is connected to the BLACK fusible link near the battery positive terminal.

[ggzilla]

There is also an S and L cast into the alternator case.

[Zombro]

Okay, for reference the horizontal of the T is the S terminal and the vertical is the L terminal as confirmed by another 720 alt.

 

So I'm not sure I am using the right stuff on the meter, but Bulb is good in cluster. cuz it blinks.

 

I put key to ON position put red prong into S terminal of plug and black prong to frame ground and it seems to be an open loop or OL.

 

So that means that cable is fried or just that somewhere along that wire is fried, right?

[wayno]

What does "open loop" mean?

[Zombro]

Means there is no continuity, as far as I under stand it. AKA no beep when testing with the multimeter.

[ggzilla]

I put key to ON position put red prong into S terminal of plug and black prong to frame ground and it seems to be an open loop or OL.

 

So that means that cable is fried or just that somewhere along that wire is fried, right?

 

That is not a normal test procedure. Your factory service manual for a 1979-up Datsun will show how to test it.

[datzenmike]

Okay, for reference the horizontal of the T is the S terminal and the vertical is the L terminal as confirmed by another 720 alt.

 

So I'm not sure I am using the right stuff on the meter, but Bulb is good in cluster. cuz it blinks.

 

I put key to ON position put red prong into S terminal of plug and black prong to frame ground and it seems to be an open loop or OL.

 

So that means that cable is fried or just that somewhere along that wire is fried, right?

 

On the 720 the horizontal White wire is connected to the BLACK fusible link near the battery positive terminal.

 

Fusible links can be blown yet look OK. Make a temporary jumper wire to go around the BLACK fusible link and see if that fixes your problem.

[Zombro]

Turns out, I'm an idiot. we noticed one plug that looked like a fusible link and it was then I realized the the batt cable is non-existent then found it on the garage floor, threw it in and its happy but the tach no want to read right like it sticks or something.

[ggzilla]

Yes, the pickups needs a battery cable.