79 210 alternator charging and idiot light.

[bosifus]

I started having charging issues with my 210 last week and was essentially running on the battery. I figured it was a no brainer and I picked up an alternator and set to work. Like an idiot I picked up the new one without taking the old one in to have tested first cause it was on the way home and the core charge was only 8$. I got the new one on and had the same issue. I cleaned up my ground points after testing the case of the alternator and having the voltage read high. Still no charging. Ground is great now though.

 

To make a long story short I did a lot of searching on the board and found an unrelated thread that touched on the charging dummy light in the dash being a potential source of the issue. Sure enough mine was blown and an 89 cent bulb was all I needed. I though I would post it up even though it was a dumb move on my part so that hopefully it will be easy to find with a search for the next guy with no idea what the hell he's doing. You can bet I'll be looking at that light to come on and go off each and every time I start my car now.

[ggzilla]

Good on ya. Maybe it will help the next guy.

[king bee66]

reminds me of when my car started smoking like a frieght train. i took it to a shop, they told me they didnt even have to do a diagnostic because the rings were obviously bad. i pulled the head off, cylinders looked fine. a valve guild was busted so i had the head rebuilt. put it back on, fucker smoked again just as before. i replaced the 1.98$ pcv valve and it stopped smoking.

 

it all made me think of how many poor 210s had been given up on because people were told they had a bad motor when it was really just a cheap fix.

[bonvo]

thats the story with most datsuns dude and its very sad really scrap a car for a 5 dollar fix

[the nice machine]

wow hey man i just got my 78 b210 yesterday... everything was normal when i drove it home. i parked it for a few minutes and when i started it back up the battery charge light wouldn't turn off and my turn signals, temperature gauge and fuel gauge wouldn't work. was this your problem? i thought maybe it was the alternator too so i put in a new one that i know works and i have the same problem.

so are you saying that your charge warning light was burned out, causing charging problems?

[ggzilla]

my turn signals, temperature gauge and fuel gauge wouldn't work.

 

That's a different problem, which can't be caused by a blown CHG light.

 

Perhaps you have blown a fuse. Check the Fuse Box.

[the nice machine]

That's a different problem, which can't be caused by a blown CHG light.

 

Perhaps you have blown a fuse. Check the Fuse Box.

 

not a fuse in the box... i've been looking for a fusible link somewhere but i can't find any. i thought maybe the the problem was the internal regulator in the alternator but it wasn't. meh... i just got the work manual today, i'll figure it out.

[ggzilla]

There is not one fuse in the fuse box?

 

are you saying that your charge warning light was burned out, causing charging problems?

yes, that is correct. If all your dash lights and gauges are not working, that causes the alternator to not charge. Now the question is -- why are your dash lights out?

 

There is no fusible link for the dash lights, T/S and gauges. There is only the Main fusible link(s) at the battery cable. 720s have two fusible links, 620s (i think) have one fusible link

[the nice machine]

There is not one fuse in the fuse box?

 

 

yes, that is correct. If all your dash lights and gauges are not working, that causes the alternator to not charge. Now the question is -- why are your dash lights out?

 

There is no fusible link for the dash lights, T/S and gauges. There is only the Main fusible link(s) at the battery cable. 720s have two fusible links, 620s (i think) have one fusible link

ummmm...you are just being a smartass about the fuses, right?

i appreciate the info... but why would a burned out dash light cause the alternator to not charge? the wierd thing is that the dash lights still work, and the gas gauge TRIES to work, but it doesn't get past the empty line.

[Boaty]

Kind of sounds like a grounding issue, to be honest.

 

Assuming you checked that, check for +12V with a voltmeter and see if you're getting a drop somewhere.

 

As far as the dash lights not letting the alternator charge...

 

A charge light excites the alternator at low RPM. It provides resistance in the circuit. When I figured out how it works, it made more sense. Might not be technically correct, but this will give you an idea of HOW it functions in a sense. Think of it this way: the bulb itself completes a circuit. The alternator starts producing power, which removes the ground. If your alternator is charging, you should have voltage on both sides of your bulb (bulb not illuminated). If there is no voltage, and the alternator is just giving a ground from the regulator (engine not running/dead alternator), then the ground completes the circuit thus illuminating the light. There's more to it than that, but that's kind of how it functions. The resistance from the bulb excites the alternator. If there is no resistance in the circuit, the alternator won't charge until higher RPM's when it excites itself. (That being said, my alternator wouldn't charge at 4K rpm so I debunked that theory, lol. Charge light? Instant kick-on.)

 

Now back to your gas gauge. Guage reads off of resistance, which goes both ways. But if you have no ground, it won't function at all.

Seeings as how you have a funky issue with lights not working and a gauge that attempts to function but can't, that is sending off a red flag for a failed ground.

 

Before you go digging into a harness and tearing things up, go verify that you have a good chassis ground, and a good engine ground. Easy mode, voltmeter at (+) terminal, ground out at chassis, and engine. If you have a mad voltage drop, well - you're not getting a ground.

 

Check the easy stuff first, even if it seems like it's something else. Process of elimination. I'm not sure if a 720 runs a main relay for harness power, but I'd start checking there if you have a ground. Could just be a bad relay, they don't live forever. Even if we want them to. Ask any 90's Honduh/Acura guy, consistant issue that causes all sorts of problems.

 

If it becomes a problemo, let me know - I might be able to run over to that side of the valley soon. I need to go to harbor freight anyways :) I love working on Datto's, everything is a challenge.

[the nice machine]

cool, thanks for the info, boaty. i will be digging in again tonight when i get home from work.

[Boaty]

Any updates?

[the nice machine]

Any updates?

 

i've been working 12 hours days so i haven't had the energy to start on it... but i have tomorrow off and i'm making a pot of coffee and going out to the garage to work on it right now. either way i will be at the sonic in medford this saturday, i'll see you there if you come down. hopefully i won't still be using hand signals to get around!

[the nice machine]

okay, i feel like an idiot now. i checked the fuses again, everything seemed good so i started checking connections, replacing light bulbs and checking for corrosion (a corroded tail light socket was keeping the turn signals and brake lights from working on my 620 for a while) so after that didn't work i decided to test the fuses one more time... and there it was, i hadn't noticed before but the test light was shorting out on one of the fuses, so i cleaned the fuse box, and it was fixed. everything is working, the alternator is charging, we're cool. it didn't look corroded, but it was just a funky connection in the fuse box. i feel stupid now but i'm sure this long drive through the hills that i am about to take will make me feel much better. you guys can go ahead and make fun of me for being foolish. i deserve it.

[ggzilla]

It's happend to me before. Glad to hear it's back on the road!