Re-wiring the alternator (A-series with L alt) URGENT

[metalmonkey47]

All related to this thread >> http://community.rat...d-overcharging/

I'm making a new thread here so it's easier if anyone searches for it for future information

 

I've been through ALL my wiring on my 210 and have found nothing related to the alternator that's out of the ordinary. The alternator has a drain on the signal wire, and is either overcharging at 16 volts or not charging.

 

The wiring on it is actually quite simple;

 

Large white wire runs from the battery to positive on the alt.

Black goes to ground

 

Then on the "T" connector theres two wires.

Large white wire that's supplies 12V to signal from the battery (Thats correct right?)

Small white/red wire to dash idiot light.

 

 

 

 

After verifying all the wiring and double checking EVERYTHING, I still have the problem. I've had 4 brand new alternators on it, so theres not a chance that I'm getting bad alternators.

 

This time, I notice the alternator is overheating and producing your typical 'burning electronics' smell.

 

 

 

A few quick questions;

 

A: Why is the alternators factory wiring supplying 12V at signal and at the alt +?

 

B: How would I go about temporarily bypassing the alternators factory wiring to get the alternator charging properly so I can verify it's a wiring problem somewhere on the harness? I need to get this done ASAP since I have to be at work tomorrow and it's my only form of transportation. It can't be just as simple as running 12V from the battery to the signal could it?

Edited April 11, 2011 by metalmonkey47

[datsunaholic]

The problem is there's not much to bypass. That "hot" wire in the T-plug (top of the "T")? Guess what- it's connected to the alternator output wire just a few inches up the harness. The idea was that the Field wire would need to be switched, so the alternator requires having both connected to work, BUT the diode trio keeps it from drawing reverse current so they eliminated the switched 12V at the plug and just left it connected all the time. The "Sense" wire (and in turn the CHG light) actually grounds through the alternator. When the alt is charging, that wire reads ~12V+, but it'll read +12V with the wire unplugged and the ignition on too since the wire gets the 12V from both directions. That's why the light goes off, because with the alternator running, there's +12V on both sides of the bulb.

 

You can pull the T-plug. The alternator won't work, but if it's still draining the ONLY answer is that the diode trio is shorted. The alternator will still charge with the trio shorted, but USUALLY the dash light comes on (with the ignition off) because it puts a +12V to the wrong side of the light bulb, and it "grounds" through the gauge cluster. The weird part is the alt light shouldn't come on when the ignition is on in that scenario, but usually it does. To test the alt in that mode, connect a solid +12V to the top of the "T" in the alternator. BUT... that will make the automatic choke relay nonoperational.

 

Which could be your whole problem in the first place.

[metalmonkey47]

Here's a more detailed explanation of the problem, just to help make sure I've covered everything.

 

 

When I bought the car, it had a drain on it. When you un-plug the alt signal, the drain ceases.My initial idea was that the diode in the alternator was shorted and faulty. Also, the charge light was on, but not fully illuminated.

 

I found that what was causing the drain is the hot white wire that's a 12V wire. The alternator that came on the car was noisy and sounded like the bearing was failing, so I replaced it with a 60amp from an L28. Literally plug and play. Prior to this, the car was charging fine, but had a drain on the battery. This was a few months ago. In the last few weeks, I've noticed the alternator has a tendency to either overcharge at 16-16.5V, or at idle, produce only 12.5-14V. At the same time, I've noticed a burning smell from the alt, and it gets hot quick, as if it's shorted. I've replaced it under warranty 4 times. All charge fine for about a week. Then problems persist. Something on the car is burning up alternators. The car has NO factory gauges and no idiot light. It's been replaced with a newer gauge.

 

Prior to reading this, I had the same idea that you suggested to just running from battery + over to the back of the signal where the 12V white wire connected, to bypass all the wiring.

 

This proved to be a bad idea.... It went up in flames after the car ran for 5 seconds.

Edited April 12, 2011 by metalmonkey47

[datzenmike]

What year L28 alternator did you use????

[I'm BLUE]

auto-zone house brand alternators ??? Wen't through 5 of them in a row on my buddy's F-150 before we found one that would charge :mellow: ,,, I know this doesn't help much BUT those alternators were shit a few years ago when I used them ( bad batch ? vendor ? IDK ) ,,, sorry :unsure:

[izzo]

auto-zone house brand alternators ??? Wen't through 5 of them in a row on my buddy's F-150 before we found one that would charge :mellow: ,,, I know this doesn't help much BUT those alternators were shit a few years ago when I used them ( bad batch ? vendor ? IDK ) ,,, sorry :unsure:

 

 

Same, i went thru 3-4 of them on my sentra, whats fucked is they would die when i was 200 miles away from home, or 100 miles from any autozone. Autozone should be banned from selling alternators. I dont give a fuck if monkey works there or not, those alternators are shit.

[ggzilla]

Large white wire that's supplies 12V to signal from the battery (Thats correct right?)

Small white/red wire to dash idiot light.

The 1978+ alternator T-connector contains L wire and S wire. If you have F, N wiring, it's the wrong alternator.

L: connects to CHG lamp in dashboard

S: connects to IGN circuit in ignition switch (or to battery for Datsun B310)

 

1. The S terminal should be 12V hot when key is turned to IGN

NOTE: on the B310 with this, S is hot all the time either way will work

 

2. The L terminal (Lamp) should be:

* 0V when key is turned OFF

* 12V (more or less) when key is turnd ON

Because the L terminal is the exciter, if your CHG lamp is burned out, the Hitachi LR won't charge.

[I'm BLUE]

Same, i went thru 3-4 of them on my sentra, whats fucked is they would die when i was 200 miles away from home, or 100 miles from any autozone. Autozone should be banned from selling alternators. I dont give a fuck if monkey works there or not, those alternators are shit.

 

:blink: thats totally fawked up ,,, agreed 100% :mellow:

[datsunaholic]

Something's screwed up in the harness, or with the choke relay. But I'd say the alternator is also screwed because it's had loads drawn through a low-load circuit.

 

The burning smell was because it was pulling current out the signal (idiot light AND CHOKE wire). It shouldn't pull much of anything. Enough to trigger the choke relay to close. But that's not the wire you were to hook +12V to... you want the "S" wire, which on my diagrams should be yellow, and it's the top of the "T". The White/Red that goes to the "L" terminal is for the light and choke relay.

 

If you hooked +12 to the "L" wire that's bad if it caught fire... means there's a dead short on one end. If you got fire when you hooked +12 to the "S" wire, well, it SHOULD have done that anyway since that's what it had before, unless the wire is already burned out. That would indicate a dead short INSIDE the alternator.

 

If the alternators you are getting have an F and N terminal, it's the wrong alternator and they'll overcharge at speed and undercharge at idle.

[datsunaholic]

The 1978+ alternator T-connector contains L wire and S wire. If you have F, N wiring, it's the wrong alternator.

L: connects to CHG lamp in dashboard

S: connects to IGN circuit in ignition switch (or to battery for Datsun B310)

 

1. The S terminal should be 12V hot when key is turned to IGN

NOTE: on the B310 with this, S is hot all the time either way will work

 

2. The L terminal (Lamp) should be:

* 0V when key is turned OFF

* 12V (more or less) when key is turnd ON

Because the L terminal is the exciter, if your CHG lamp is burned out, the Hitachi LR won't charge.

 

 

Sometimes they'll charge with the bulb burned out, because the choke relay pulls enough current to engage the exciter.

 

That's why I'm thinking that the choke relay is shorted, causing this whole issue.

[datzenmike]

What year L28 alternator did you use????

 

If '77 or older they are wrong and you are just replacing them with wrong ones.

[ggzilla]

Yes, a 1978-up Datsun needs S, L wiring on the alternator. F, N wiring is for older cars and non-USA datsuns. Pumpkin had that problem on his 210 (older alt) and it was eating batteries and getting acid puked out.

[datzenmike]

All related to this thread >> http://community.rat...d-overcharging/

I'm making a new thread here so it's easier if anyone searches for it for future information

 

I've been through ALL my wiring on my 210 and have found nothing related to the alternator that's out of the ordinary. The alternator has a drain on the signal wire, and is either overcharging at 16 volts or not charging.

 

 

Are we talking about two different cars? This morning you said:

 

 

Yeah, I've found the problem (kinda)

 

 

I unwrapped ALL the wiring under the hood and back through the firewall and discovered the fucking PO cut out a harness from another car and spliced it into this car and tried to hide it I'm uber pissed. It's HORRIBLE.

 

At least twice I've asked if this was an external regulated alternator from a 280z?

 

Why are we starting a second post on this?

[metalmonkey47]

What year L28 alternator did you use????

1979 I believe? I made sure it was internally regulated. AutoZone P/N is 14303 for reference.

 

auto-zone house brand alternators ??? Wen't through 5 of them in a row on my buddy's F-150 before we found one that would charge :mellow: ,,, I know this doesn't help much BUT those alternators were shit a few years ago when I used them ( bad batch ? vendor ? IDK ) ,,, sorry :unsure:

Idk why it happens We use the same vendors as Advance and Orielly, but that doesn't mean anything. I'll go back for a new one later.

 

Something's screwed up in the harness, or with the choke relay. But I'd say the alternator is also screwed because it's had loads drawn through a low-load circuit.

 

The burning smell was because it was pulling current out the signal (idiot light AND CHOKE wire). It shouldn't pull much of anything. Enough to trigger the choke relay to close. But that's not the wire you were to hook +12V to... you want the "S" wire, which on my diagrams should be yellow, and it's the top of the "T". The White/Red that goes to the "L" terminal is for the light and choke relay.

 

If you hooked +12 to the "L" wire that's bad if it caught fire... means there's a dead short on one end. If you got fire when you hooked +12 to the "S" wire, well, it SHOULD have done that anyway since that's what it had before, unless the wire is already burned out. That would indicate a dead short INSIDE the alternator.

 

If the alternators you are getting have an F and N terminal, it's the wrong alternator and they'll overcharge at speed and undercharge at idle.

 

Can you elaborate more on 'S', 'N', and 'F' terminal? Are you referring to the plug? (Sorry for the ignorance, I'm still new to Datsun's and electrical circuits) As far as the choke relay, i had heard about the problem before, so the relay was removed from the car before I was troubleshooting. This is kinda a screwy problem

If '77 or older they are wrong and you are just replacing them with wrong ones.

 

Nah, I made sure it was an IR unit before replacing I didn't need regulator issues

 

 

Sorry to make a new thread, I needed to get it solved ASAP since I have to drive the car tomorrow for work, but it looks like that won't happen since I burned up the alt

 

And sorry about that last question before, I was in a hurry and missed that

Edited April 12, 2011 by metalmonkey47

[datzenmike]

No problem. Now we're getting somewhere.

[metalmonkey47]

for reference, here's a picture of the back of the alternator. (NOT my exact one)

 

 

[ggzilla]

Yes, it's teh T-connector wiring that makes the difference.

Stamped in the case look for FN or SL (or it may say nothing like in the photo).

 

210 came with an LR150 unit. LT150 is the older kind. LT vs LR.

Rebuilt units are commonly AL238X for the 210.

Or look for a Nissan part number in the case:

23100-H7703

23100-H7702

23100-H7701

23100-H7700

[datsunaholic]

OK, let me grab my handy-dandy 1981 Datsun 210 Factory manual.

 

I see I was mistaken on wire colors. The "S" terminal (the "top of the T") on a B310 is white. So is the main "B" wire (output wire). They're wired together in the harness. On older IR Datsuns the "S" wire was yellow.

 

The White/Red Stripe wire is the "L" wire, bottom of the "T". That goes to the Auto-choke relay and the "CHG" light on the dash, and nowhere else.

 

If you have NO charge light and NO Auto-choke relay, then that wire should read NOTHING. It's an open circuit, neither ground nor +12 nor anything.

 

If that wire is left open, the alternator won't work. It'll be erratic, usually won't even charge but on occasion they will charge because of floating current. If that gets hooked up to +12 or ground bad, bad things will happen. At a minimum, it needs a light bulb connected between it and a switched 12V source. Conversely you can put a 100Ω resistor from a switched 12V source to that terminal.

[metalmonkey47]

Okay, heres what I've done today;

 

I went ahead and pulled the alternator and swapped on my spare alternator, and the car charges in the normal 13.9-14.2 range. However, I still do have the drain.

 

The"L" alternator that came off the car had no castings or numbers on it, so I'm not sure what model it is.

 

 

I didn't hook up an idiot light yet, since I don't have time time before work, but I put a multi-meter on the charge light wire and had 14 volts at it, so the charge light is "on." At least it's driveable

[datsunaholic]

14V at the charge light wire is actually "off", which means charging... I know, sounds backwards, but it takes a little electrical engineering to know the whys and hows.

 

The way it works is that the charge light has 12V from the ignition and grounds through the "L" terminal on the alternator when the alternator is not spinning. When the alternator starts charging, you get a 12-14.5V output at the L terminal, which combined with the 12-14.5V at the ignition, combines to make 0V at the light bulb, so the bulb goes off.

 

I realize that the L and S terminals aren't marked. I looked at the few alternators I have left (most of my stash is now in storage 100 miles away) and most of the IR ones don't have the T plug terminals labelled, or at best only have one labelled.

 

Only thing I can say is if you still have a drain when the T-plug is UNPLUGGED then it's either not the alternator or it is the alternator. Only way to know is to start isolating things. If it only drains with the T-plug plugged in, it's probably a wiring issue since your harness is hacked to hell from what I gather in the other posts. You ABSOLUTELY should NOT have 12V at the white/red stripe wire with the ignition OFF, plugged in or not plugged in.

[metalmonkey47]

Hmmmm, okay that all makes sense to me now! So the alternator is NOT the problem in this case then as far as the drain.

 

I think I'm looking at the wrong end of the wire. I guess my next step should be to trace the wiring from the gauges back.

 

 

 

I see what you mean about the "l" and 'S' terminals now as well, I got a better look at the alt now and I see it.

 

 

For the time being, I think what I'm going to do since my existing alternator is charging fine, I'm going to hook a relay to switched 12v on one side and the alternators 12v signal wire so when the ignitions off, the relay is open and theres no drain, just long enough for me to either locate a parts car with an unmolested harness or find the wiring issue.

 

 

 

 

 

 

Thanks for the help I'll update if needed.

[metalmonkey47]

UPDATE!!

 

With the old alternator on the car, I test drove it today when I had it back together, and I noticed the alternator wasn't charging at idle, and like before, would charge at about 13 volts while driving. I popped the hood and saw that the wire that runs from the fusible link was melted and when i felt it, it was burning. I unhooked the alternator signal to disable the wire and took it straight home, running on what I assumed was just the battery.

 

I got half way down the road, looked at my gauges and the alternator was charing at about 13.5 volts, and was sustaining 13 volts at idle. The T signal wire was unhooked, so how the hell is it possible that the alternator was still charging??? I confirmed with a voltmeter.

[ggzilla]

The T signal wire was unhooked, so how the hell is it possible that the alternator was still charging?

This is possible because the alternator has a BAT and EARTH wire. If there is an internal short, it can activate the "S" circuit all by itself.

 

As a double-check, remove the BAT wire from the alternator and tape it somewhere safe. Now drive it around...

[Datmorris]

I'm new to this forum and could use some advise before I continue wiring things up. I have a 80's A-14 stuck into a 55 Morris Minor, something I have done off and on over the years, but always worked off of the stock Morris wiring harness. This time it's different with a aftermarket wiring harness that is very basic. I'm concerned about correctly wiring up L alt. correctly.

 

This forum has given me great insight to what I need to do, but want to make sure I do it correctly just the same. My question is on the LR 150

S term is a large white wrie and believe that goes to the ing switch, L term white w/red stripe would normally go to the charge light, in my case no charge light and want to know what I can connect it to safely to make it functions properly.

[ggzilla]

Hitachi LR150 alternator is used by many cars (it is not specifically for the Datsun L-series engine).

 

I don't know what the answer is, can you create a New Topic for this new question? I believe all Datsuns use a CHG lamp.