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JTCN

1975 280z New ZX Alternator Won't Charge

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Unfortunately after doing all of the steps in the swap guide, my alternator isn't charging the battery.

With the car off the battery had 12.5v

I turned it on (no lights/accessories) and it was around 12.4v

With lights and fan on highest speed it was 12v. And the fan was hardly blowing on its highest speed.

 

All of the wires for the 1975 year in the guide were the right color on my car, so I crimped the Green/Red wire to the White/Black wire.

Then I crimped White to Yellow.

 

The rest of the wires (Green and Black) I taped up the ends and left them dangling.

I think I did the wiring correctly, but I figured I'd post how I did it anyway.

 

For the alternator wiring I connected battery, earth, and the "T" connector.

But I found a strange blue wire in my battery connector for the alternator.

I think it connected to this thing on the back of the alternator. (Not my pic but it shows where it connects on the original alternator). http://img.photobuck...zps87ef6ea3.jpg

My old alternator had the blue wire plugged into that thing but it broke off just from me touching it.

My new alternator has one of those cylinder-shaped things on it but its connected to a bolt on the alternator itself. (Sorry I don't know what the things called lol)

 

So for my first question, do I need to connect this blue wire somewhere? Could that be why it isn't charging?

Here's an album I just made so you guys can see some pictures of it all. http://imgur.com/a/gM5pj

If you guys see anything in these pics that even MIGHT be a problem, please let me know.

Also If you guys want some more pics I'll go out and take some.

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If L doesn't get power with the key on the alternator won't charge.  Do you have a meter?  Is your ammeter connected?  Have you had the car long?  Did the old external regulator system work?  Why did you decide to do the swap?  Is the alternator body grounded?

 

The thing is called a condenser.  The body is grounded and the wire is connected to the main charging wire.  

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Yeah I have a meter, I'll check L with it in a minute.

The ammeter is connected. It goes down when I turn accessories on in the car.

I've has the car for a year. Im switching to the internal reg. Because i was hitting 16v while revving the car and I was having dim lighting issues.

I connected the earth wire to the alternator so I think its grounded.

What should I do with that condenser wire? Its just dangling right now.

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Also, Check the voltage At the alternator when it is running.... If it isnt around 13-14V..you may have a bad alternator or a high resistance short between ground and battery  To check this remove the wire to battery from the alternator and start it up again.

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The wire connects to the thick charging wire.

 

You should always check your work with a meter if you can.  It will save you a lot of time.  If you don't have battery voltage at the T plug with the key on, work back in the wiring until you find the problem.  The 1975 wiring diagrams will help you also.  The Engine Electrical chapter has small specific diagrams so you don't have to use the big one.

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But I found a strange blue wire in my battery connector for the alternator.

 

1975 doesn't show a blue wire but 1976 does.  Use your meter to find the switched power wire.  You might have 76 colors in your 75.  Nissan changed things on the fly sometimes.

 

And what does "battery connector for the alternator" mean?  Doesn't paint a picture.

post-8864-0-31474200-1486674359_thumb.png

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1975 doesn't show a blue wire but 1976 does.  Use your meter to find the switched power wire.  You might have 76 colors in your 75.  Nissan changed things on the fly sometimes.

 

And what does "battery connector for the alternator" mean?  Doesn't paint a picture.

The blue wire I'm referring to isn't tied into the regulator harness. It's literally coming out the back of the plug for the battery to alternator cable.

This isn't a great pic but you can see it coming out from the rubber boot over the battery cable.It's the yellow wire next to the white/red wire. http://imgur.com/On5jBDJ

 

 

Also, Check the voltage At the alternator when it is running.... If it isnt around 13-14V..you may have a bad alternator or a high resistance short between ground and battery  To check this remove the wire to battery from the alternator and start it up again.

Alright so how do I check the voltage a wire is getting? Do I set the meter to DC 20v and touch both probes to the wire? Sorry for the noob electrical questions.

 

 

The wire connects to the thick charging wire.

 

So... what do I do with it? Is it important?

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That's the condenser.  And the charging wire (withe with red stripe).  The battery cable is the one that goes from the battery to the start lug.  It's big and thick.  Like a cable.

 

Just connect it like it's shown in the picture.  To the BAT terminal.  The wire end of the condenser connects to positive, the body to Earth/ground.  E.  It is there to absorb electrical noise.   Don't leave the blue wire coming out of the harness disconnected because it might short to ground.  Hopefully it hasn't already.

 

Check your fusible links while you're in the engine bay.  To be sure you didn't short something and blow a link.

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Okay let's get this straight. The blue wire goes to the condenser. When I removed the old alternator the blue wire came off of the condenser. I installed the new alternator and it has a condenser already installed. It's connected to the BAT terminal on the alternator. Now I'm left with this blue condenser wire coming off of the charging wire.

So since I already have a condenser and it's plugged onto the BAT terminal, I don't know what to do with the old condenser wire.

For now I think I'll tape it up and forget about it for a little bit.

 

I'm going to test the voltage going to the "T" connector and charging wire.

Edited by JTCN

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Just got back from checking the voltage at L on the "T" connector.

0v with the key off and I was getting 12.5 with the key on.

I took the "Charging wire" off the BAT on alternator and tested the charging wire. ( Is this what I was supposed to check on?)  With key off it was getting 12.5v, key on 12.5v, and when the car was running it was getting 11v.

 

Where do I go from here? Could it be the wiring I have done to the voltage regulator harness? I think I got it right but I don't know where else to look.

 

Edit: took a quick pic of what the back of my alternator looks like if anyone was wondering. http://i.imgur.com/fRSOvqZ.jpg

Edited by JTCN

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We've overlooked one of the basics of most Z and ZX alternators, especially the parts store remans - they don't put out much current at low RPM.  Did you rev the engine and check voltage?  If you have battery voltage at the L terminal (the bottom of the T) the alternator should charge if it's spinning and nothing is drawing it down.  Your battery is getting low, 12.4 means it at about 70% and needs a charge, and it might be drawing all of the current if you're doing your voltage checks at idle RPM.

 

If you give it a rev and it still doesn't charge, have it checked at a parts store.  Parts store remans aren't known for high quality, generally.

 

Your wiring seems right.  It should work.

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We've overlooked one of the basics of most Z and ZX alternators, especially the parts store remans - they don't put out much current at low RPM.  Did you rev the engine and check voltage?  If you have battery voltage at the L terminal (the bottom of the T) the alternator should charge if it's spinning and nothing is drawing it down.  Your battery is getting low, 12.4 means it at about 70% and needs a charge, and it might be drawing all of the current if you're doing your voltage checks at idle RPM.

 

If you give it a rev and it still doesn't charge, have it checked at a parts store.  Parts store remans aren't known for high quality, generally.

 

Your wiring seems right.  It should work.

Yep I was revvin it pretty good while testing. Gonna check all my connections in the morning to make sure they're real good and test it one last time.

If that doesn't work I'll pull the alternator out and drive to autozone and get it tested. Maybe I'll get lucky.

 

Thanks for the help everyone, I'll update this post with what they say and what I'll do after that.

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If you happen to read my build thread I mention a very poor experience with Autozone testing my alternator on an older Maxima that was my daily, caused me a lot of grief until I bought a high quality multimeter and tested things myself only to find out the alternator was definitely bad. Wasted a lot of time chasing other potential problems and had to have the car pushed across a bridge by an officer and later had to be towed when I thought I had fixed things.

 

Needless to say I wouldn't recommend getting anything electrical tested at Autozone. I've trusted NAPA more lately. 

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If you happen to read my build thread I mention a very poor experience with Autozone testing my alternator on an older Maxima that was my daily, caused me a lot of grief until I bought a high quality multimeter and tested things myself only to find out the alternator was definitely bad. Wasted a lot of time chasing other potential problems and had to have the car pushed across a bridge by an officer and later had to be towed when I thought I had fixed things.

 

Needless to say I wouldn't recommend getting anything electrical tested at Autozone. I've trusted NAPA more lately. 

Yeah I'm sure I can't expect good quality from autozone, but I'm just looking for a confirmation if I just got a dud alternator or there's a problem with my connections.

Would honestly be relieved if the alternator is faulty, at least then I know I didn't screw anything up.

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So test the alternator with a multimeter like Greeko Mentioned. And work back

 

This. I didn't buy my alternator from them. They gave me a false positive when they tested the one I had. That's why I'm saying test it with a multimeter or have it tested somewhere else. 

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Just got back from running all over town and getting the alternator tested.

I took it to autozone and it passed every test. shit.

I'm gonna try re-wiring the splices I made in case it was a crappy connection.

How do I test the voltage output at the alternator? I know it's not reaching the battery if it is charging, so I can't measure it at the battery terminals.

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Are you sure that there is continuity to the battery positive post from the alternator's charging wire, the BAT terminal?  Follow the path.  You can test if it's charging by measuring between the BAT terminal and ground, directly from the back of the alternator.

 

You can test continuity by measuring battery voltage at the BAT terminal directly with the engine not running and key off.  The BAT terminal is always connected to the battery positive post, normally.  Did you check those fusible links yet?

 

You might just stop, now that you've been working on this problem for a while, and think about how the system works, and what should be connected to what.  Could be that you've been assuming that the charge wire is connected to the battery, but it's not.

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Okay so I just went out to check with the meter with my dad and we found out that the earth on the alternator is getting 12v from the positive on the battery.

The BAT terminal is getting 0v from positive, and 12v from negative.

Somehow this got switched up and my dad says he can't believe it hasn't fried anything.

How the hell did this happen? I checked my fusible links and they're both fine, along with all the fuses in the cabin.

Am I screwed?

Edited by JTCN

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Well turn it on and see! hold one before you do hopefully you didnt do any serious damage.

So you had the positive that suppose to go to (battery ) I think through starter on the earth (ground) of alternator? I am surprised you were running. THE POS terminal on the alternator should have plastic/rubber between the housing and its labeled BAT.

Secondly are you sure your multi-meter is on the correct probes I know it sound silly but double check your colours . Rather you switch them now than really fry sh*t up. The only possible way I I can think of that you didn't burn fusible links/charging wire is if your BAT on alternator isnt hooked up to POS on starter OR your BAT POS isnt hooked up HOT ( POS ) on starter. Make sense?

 

Thirdly if you checked multi-meter and confirmed it isnt the probes simply by testing them on battery or alternator. Are you getting -12v reading on the multimeter on BAT on alternator with it connected to the RED probe and black connected to earth?!?!?!

 

Check voltage at battery terminals. Also keep your + probe on + battery and switch - to engine / alternator just to see if its a ground issue.

 

Check voltage at starter + (hot) terminal on starter and - use the starter body, and switch the ground probe to the - on battery see if there is any difference. YOU SHOULD READ SAME AS YOUR BATTERY VOLTAGE if not then you got a + or - from bat to starter is not connected properly , BUT I highly doubt that cause your car starts!

 

With the car off Check voltage at alternator using the BAT for + and body of alternator as - , then keep + lead of multimeter on BAT and switch - to neg battery YOU SHOULD READ SAME AS YOUR BATTERY VOLTAGE if not you need to connect that thick ass wire from BAT to + of starter.

 

Start engine. do the same last test you should be at least charging 13.5-14.2v at your alternator. If your not rev it up a lil doesnt need much.

You either have a bad alternator, loose belt, or wiring .

If its your wiring pull out the T connector and you should start overcharging non regulating and will spike up to 14.7-17v .

If you are charging but not getting it to the battery then do same first 2 checks in reverse order and work back. Good luck

Edited by softopz

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Well turn it on and see! hold one before you do hopefully you didnt do any serious damage.

So you had the positive that suppose to go to (battery ) I think through starter on the earth (ground) of alternator? I am surprised you were running. THE POS terminal on the alternator should have plastic/rubber between the housing and its labeled BAT.

Secondly are you sure your multi-meter is on the correct probes I know it sound silly but double check your colours . Rather you switch them now than really fry sh*t up. The only possible way I I can think of that you didn't burn fusible links/charging wire is if your BAT on alternator isnt hooked up to POS on starter OR your BAT POS isnt hooked up HOT ( POS ) on starter. Make sense?

 

Thirdly if you checked multi-meter and confirmed it isnt the probes simply by testing them on battery.

Check voltage at battery terminals. Also keep your + probe on + battery and switch - to engine / alternator just to see if its a ground issue.

Check voltage at starter pos using body of starter and the + (hot) terminal on starter, and switch the ground probe to the - on battery see if there is any difference. (also checking your grounds while your at it)

With the car off Check voltage at alternator using the BAT and body of alternator and keeping the pos lead of multimeter on BAT and switching neg to neg batter you

Start engine. do the same last test you should be at least charging 13.5-14.2v if your not rev it up a lil doesnt need much.

You either have a bad alternator, loose belt, or wiring .

If its wiring pull out the T connector and you should start overcharging non regulating and will spike up to 14-17v .

If you are charging but not getting it to the battery then do same first 2 checks in reverse order and work back. Good luck

First, thank you so much for the long write-up.

I didn't mess up any connections to the alternator itself, the charging wire goes to BAT, earth to earth, and the "T" connector to its connector.

Yes, the BAT terminal has the plastic around it.

I definitely didn't get the probes mixed up.

Heres a pic of the back of my alternator just to confirm: http://i.imgur.com/fRSOvqZ.jpg

 

The only wiring I did on this car was splicing the voltage regulator harness... Maybe it's just me but I don't see how that could screw this up so bad

How can I check if my charging wire is connected to positive on the starter? Do I have to rip open the harness and chase it back?

I don't understand how this is happening because to my knowledge everything is connected and wired correctly.

 

Here's an album of some other pics I took of my wiring and the alternator. http://imgur.com/a/gM5pj

One last thing, the condenser's wire on my alternator is connected to BAT terminal, is that correct? It's what it was connected to when I got it.

 

Edit: I've also been getting small sparks when connecting the negative cable to battery negative terminal.

Edited by JTCN

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Just did some of the tests you suggested.

Battery voltage is 12.58

Battery POS to Alternator earth is 12.58

Starter POS to starter case is 12.58

Starter POS to BATTERY NEG is 12.58

Alternator BAT to alternator case is 12.58

Alternator BAT to BATTERY NEG is 12.58

 

I did all these tests with the car off.

I havent started the car since I found out about the car getting to ground, but it was running just fine. Just wasnt charging.

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